Piston or non-piston AR platform

rjohns94 · Post by **rjohns94** » Tue Sep 09, 2014 8:42 pm

Which do you guys prefer? AND.......

Thoughts on the Stag Arms platforms, specifically the 8T?

Old Ironsights · Post by **Old Ironsights** » Tue Sep 09, 2014 9:08 pm

If I had to buy an AR, it would be Piston.

Nothing I hate more than roto-rootering a Gas Tube because I can't get a replacement. At least with a Piston, it's not quite such a challenge to clean.

But then, I'm an HK guy and dislike gas guns in general.

Mescalero · Post by **Mescalero** » Tue Sep 09, 2014 9:25 pm

That is why I have a Daewoo.

Malamute · Post by **Malamute** » Tue Sep 09, 2014 9:34 pm

I think the piston guns are over rated, and the "issue" of DI overblown.

Most of the AR's I've had have been Colts, and worked extremely well, more so than the AK's I've been around. In many thousands of rounds, I had one extractor spring go bad in an early A-2 carbine, and I dropped one magazine on a rock and damaged the feed lip on one side. It would only feed off one side of that magazine. Got rid of magazine, problem solved.

Just looked up the 8T. It looks like you can buy a Colt for less money. I don't know much about Stag, and in general, my mostly uninformed inclination is to stay with the best known name(s) and standard types.

MrMurphy · Post by **MrMurphy** » Tue Sep 09, 2014 10:16 pm

The AR-15 was designed to be a DI (direct impingement) gun specifically to be simple and keep the weight down. Stoner was a Marine rifleman, 'grew up' on the M1 Garand. If he'd wanted a piston, he'd have put one in.

There is absolutely no need to "EVER" clean the gas tube on an AR-15. There is 52,000 psi if I remember right, going through there every time you press the trigger. If it's still in there after 1 shot, it's not coming out with a pipe cleaner.

Way back in the 60s, the Army had Colt develop a piston M16 prototype to see if there was any potential improvement.

You'll notice it didn't get adopted.

Piston ARs tend to have issues with carrier tilt and parts wearing in places they weren't meant to, because the parts were never designed to work with a piston and the different pressures they exert in different places.

If I 'had' to go with a piston AR, I would choose an LWRC. Through long experience with them and the company itself, LWRC gets it right.

Stag isn't bad quality for an average shooter, but considering you can get a Colt 6920 (which, aside from 1.5" more barrel and lacking the Group Therapy Option third selector switch position, is identical to the issued M4 carbine) for $1097 at Walmart as of 2 days ago when I saw one......why would you go with a lesser quality piece?

Edit: The primary reason piston ARs became The Hot New Thing is when Delta, the SEALs and some other special ops groups started using the HK416. The HK was designed specifically to address issues they noted. 1. Suppressed 2. Very short barrels (10-11") 3. Full auto with 1. and 2.

In these particular situations, a piston gun does tend to perform somewhat better than a standard DI rifle, blowing less gas back through the action and keeping the action cleaner due to the overpressure from suppressors IIRC.

Unless you're doing the above.....it's unnecessary.

Old Ironsights · Post by **Old Ironsights** » Tue Sep 09, 2014 10:21 pm

I've seen an awful lot of M16s deadlined with plugged gas tubes. Tubes so carboned up that they could not be cleaned and had to be replaced.

Granted, this was over 20 years ago and they were A1s, but still...

There's no denying that DI works, I'm just not a fan.

OldWin · Post by **OldWin** » Tue Sep 09, 2014 10:28 pm

I haven't owned an AR in almost 20yrs but I agree with Mr. Murphy.
The AR wasn't designed as a piston system and cramming one in it is going to cause more problems than you think you had in the beginning. Engineering isn't that simple.
The other problem is that every company tried their hand at it and nothing is standardized, making parts replacement a potential nightmare.
If you want an AR, buy one as it was designed to run with the best quality you can find.
If you want something pistin driven, buy a different rifle.

My .02

Chris83716 · Post by **Chris83716** » Tue Sep 09, 2014 10:36 pm

Piston is a solution in search of a problem. Lube and good quality ammo/ magazine are the solution to 99% of the "problems" with AR's.

Chris

FWiedner · Post by **FWiedner** » Tue Sep 09, 2014 10:44 pm

Malamute wrote:I think the piston guns are over rated...

I'm on this page.

Malamute · Post by **Malamute** » Tue Sep 09, 2014 11:06 pm

Old Ironsights wrote:I've seen an awful lot of M16s deadlined with plugged gas tubes. Tubes so carboned up that they could not be cleaned and had to be replaced.

Granted, this was over 20 years ago and they were A1s, but still...

Were they shooting a lot of blanks?

Frank has commented several times about how horribly dirty blanks were to shoot.

MrMurphy wrote:There is absolutely no need to "EVER" clean the gas tube on an AR-15. There is 52,000 psi if I remember right, going through there every time you press the trigger...

I believe port pressure is quite a lot less than chamber pressure, but still quite capable of keeping the gas tube clear unless using black powder or blanks much.

jkbrea · Post by **jkbrea** » Tue Sep 09, 2014 11:20 pm

I taught a Patrol Rifle class for years. We would go through 500 to 1000 rounds in a day and a half. I never had an AR go down because of a gas tube but I did notice that the piston AR's rarely had to be cleaned. Just at the end of the day. On the other hand, the regular AR's had to be oiled several times throughout the day or cleaned at least twice or you had to use the forward assist every other shot. After a couple hundred rounds, the bolt starts moving a lot slower and would have feeding problems. For police and citizens they're great but I could see in a combat situation where a Soldier/Marine could go through dozens of magazines quickly, the piston driven ones would be preferable.

MrMurphy · Post by **MrMurphy** » Wed Sep 10, 2014 12:48 am

Look up "Filthy 14".

http://www.slip2000.com/blog/s-w-a-t-ma ... filthy-14/

Using correct lube (CLP works, but like any 1 product trying to do 3 things, it does none of them overly well) but Fireclean, Slip 2000 and a few other modern lubes will keep an AR running long beyond any potential firefight.

An excoworker was involved in a 3 day action in Afghanistan where if I remember correctly, he expended 20-28 magazines from his personal rifle over those three days without having time to clean the rifle in more than a quick wipe of the BCG. It ran fine.

If a gas tube needs to be 'cleaned' then it actually needs to be 'replaced'.

7.62 Precision · Post by **7.62 Precision** » Wed Sep 10, 2014 1:01 am

jkbrea wrote:On the other hand, the regular AR's had to be oiled several times throughout the day or cleaned at least twice or you had to use the forward assist every other shot.

If this is the case, it is because the rifles were not lubed to begin with or had other issues. We also do carbine courses, and I have trained extensively with and used the M16/M4 in combat. The AR platform is a very reliable platform and handles high volume of fire just fine.

7.62 Precision · Post by **7.62 Precision** » Wed Sep 10, 2014 1:30 am

On the issue of pistons:

The DI system IS a piston system. Ever pull the piston out of a car engine? What does it have around it? Rings! So does your AR bolt. Your bolt is a piston.

The AR platform was designed as a DI system, and it works just fine that way. Despite the marketing hype, it is a more modern system. Long and short-stroke piston systems were used before DI systems were.

The DI system simplifies the rifle, improves the recoil impulse, and has easier accuracy potential.

If you have an AK, you should have a piston system. If you have an M14, you should have a piston system. If you have a Ljungman AG42b, You should have direct impingement. If you have an AR, you should have direct impingement. It is how it was designed, and how it works best. If you have some irrational objection to a DI system, by a rifle that was designed to use a piston system, or delayed blowback, or whatever system you like.

I work with a company that designed a drop-in piston system for ARs. They are a serious world-wide supplier of military equipment. I know the guy who was in charge of the project and the company very well. He is very much a perfectionist in this sort of thing. They invested a great deal of money and time in designing the system. He told me that he tested every available gas piston system and the one they designed was the best. If he said so, it is the truth. They tested it and the other systems extensively. This project took several years. At the end, he shelved the project. He told me that every gas piston system they tested had issues. His system, which he said was better than the others, could not be proven to be a true advantage. The only thing he said that he could conclusively prove, with many thousands of round fired, is that like the other systems available, his resulted in a very slight decrease in reliability, and some of the systems caused a major decrease in reliability.

The resin gas piston systems exist for the AR is because of attempts to leverage military contracts. HK wanted a military contract, but did not want to compete on price. So they designed a piston M4 and began a campaign to convince the US military that it was a needed improvement. For the most part, this campaign failed to secure any really notable contract, but it did succeed in convincing the public, who clamored for gas piston systems, which resulted in manufacturers offering them and adding more marketing hype into the frenzy, and then people began really believing that they were an advantage. I fell for it at first, but real-world experience proved the marketing hype to be just that. The problem is, of course, that everyone who overspent on a gas piston AR needs to justify the purchase and continues to spread the hype.

When I see ARs having issues, it is almost always due to one of two things, neither of which is the DI system. The number one issue is new, rough rifles that have been fired little and lubed not at all. Second is out-of-spec parts or shoddy assembly.

When students come to take a carbine course, I lube their rifles for them the first morning, showing them how. I learned to do this when a large percentage of students were running their rifles dry. Also, I use older,well-proven lubes. Not all the hyped-up new wonder-lubes are all they are advertised to be, or may work fine on a bolt gun, but not a semi-auto. By the way, for the gas-piston-only crowd, we see more malfunctions in AK courses than AR courses, and AKs need lube just like ARs, as does the gas piston Garand that needs some grease as well. So don't tell me a gas piston makes it so you don't have to clean or lube.

The gas piston systems also create other issues including wear issues, since they tip the bolt carrier and recoil impulse is different.

If you are getting an AR, invest your money in a quality rifle or quality parts, don't waste it on a gas piston system. If you are looking spending the money on a piston AR, you are already in or over the price range of an LMT or Bravo Company or Colt, etc. DI AR. I pretty much go for LMT rifles these days.

7.62 Precision · Post by **7.62 Precision** » Wed Sep 10, 2014 1:44 am

Now, there is one reason the government, especially the Navy, was interested in piston rifles. It has nothing to do with reliability. It has to do with a little-recongized problem; the thermal cycling of optics.

People have recognized that the government's interest in piston rifles had to do with heat. As a result, there are many myths about the heat problem. You will hear a lot of claims that the DI system heats the bolts up and causes them to break. This is not the case. The bolts were heated much hotter in their heat treatment. You can melt the barrel on an AR and never heat the bolt enough to damage it - it has been done multiple times.

The heat does not cause the upper to crack - you cannot get it hot enough by firing to do so.

However, aluminum is a great conductor of heat, and most optics have aluminum mounts and bodies and the upper is aluminum. So while the average soldier never heats his rifle up enough to do any damage, there are certain units whose training consists of large volumes of fire in short amounts of time, on a regular basis, such as some particularly famous Navy units. While most modern optics can be heated up to very high temperatures once or twice and survive, the heating to much lower temperatures followed by cooling, and the constant repetition of this cycle, will break down the adhesives in the optics and cause the optics to fail. The electronics can be effected in some sights as well. I am talking about all of the optics in common use by the US military.

So certain units are going though optics due to the nature of their training. There are a couple solutions. My solution is to use the Meprolight optics. They were designed specifically to handle the thermal cycling and are not damaged. The Navy's solution was the SCAR, which was designed as a piston rifle and isolates the heat from the optics. Also, the SCAR has a reciprocating charging handle that is an advantage when coming out of the water.

Thermal cycling will never be an issue for the average shooter - most can't afford that much ammo. It will never be a problem for most law enforcement or for most soldiers. If you are worried about it, buy a SCAR. Or do like me and buy DI ARs and Mepro optics.

Panzercat · Post by **Panzercat** » Wed Sep 10, 2014 2:24 am

Piston gun. In fact, I've got my eye on a Rainier Arms that I probably won't be able to even talk about with my wife until next year

I could go into my reasoning, but this is almost as contentious as caliber discussions. Suffice to say, I'm comfortable with my decision after a lot of research.

7.62 Precision · Post by **7.62 Precision** » Wed Sep 10, 2014 2:41 am

The thing is, caliber discussions are one thing, since many calibers overlap and do the same things as well as other calibers.

On the other hand, the piston AR discussions are almost always fueled by misinformation designed to sell you stuff you don't need. The problem with researching it, is you turn up so much misinformation that takes some work to separate from the truth.

If I was buying a piston rifle, it would not be an AR, I would get something designed around that type of action.

cshold · Post by **cshold** » Wed Sep 10, 2014 4:20 am

FWiedner wrote:
Malamute wrote:I think the piston guns are over rated...
I'm on this page.

At least you're on a page.
I was well past halfway through this thread before I
realized the topic wasn't about air rifles

AJMD429 · Post by **AJMD429** » Wed Sep 10, 2014 7:28 am

I did switch my 'shorty' AR to a piston one since I keep my Trek (suppressor) on it almost all the time; I was getting failures to extract and don't have that any more. Still not sure WHY it makes a difference though; I thought the issue with suppressors was the extra soot blowing back via the chamber, not through the action...

Malamute · Post by **Malamute** » Wed Sep 10, 2014 10:04 am

Good posts 7.62.

What buffer are you using AJMD?

What I had understood to be the rational for piston was in suppressed and high volume full auto, together in that combination. Could well be that just a suppressor alone changes the equation, though changing the buffer and spring may do the same thing in the end. Shorties aren't generally considered to be as reliable for a couple of reasons, and a suppressor may tip it over the edge into needing some other changes. The guys building AR pistols have discussed H2 and other buffers, some do OK with carbine buffers. Seems the shorter you go, the more it can matter.

Does a suppressor change the port pressure, or perhaps the port pressure dwell time? The guys using them mention using different buffers, and sometimes a different bolt carrier (a heavier one to slow it down a little?). AJ, I wonder if the piston stuff adds enough weight to achieve the same end?

7.62 Precision · Post by **7.62 Precision** » Wed Sep 10, 2014 10:41 am

AJMD429 wrote:I did switch my 'shorty' AR to a piston one since I keep my Trek (suppressor) on it almost all the time; I was getting failures to extract and don't have that any more. Still not sure WHY it makes a difference though; I thought the issue with suppressors was the extra soot blowing back via the chamber, not through the action...

If I had a very short AR, I would use a piston.

The DI system in the AR was designed for a 20" barrel. It works fine with a 14.5" barrel, especially if you use a heavy buffer like Colt, or adjust the gas port size like LMT. When you go shorter, the rifle starts getting over-gassed, unless you redesign the system, which was not really done. So a piston regulates this and keeps the action from running too hard and too fast. If the gun is way over-gassed, you can get failures to extract as the chamber pressure is still too high to extract when the rifle cycles.

The suppressor also often increases the gas pressure.

octagon · Post by **octagon** » Wed Sep 10, 2014 10:52 am

Never had a single malfunction from my Sig M400 in ALL the rounds I've put through it. All ten rounds, NO malfunctions. I did not want the Evil Black Gun, mine is green.

Mescalero · Post by **Mescalero** » Wed Sep 10, 2014 10:57 am

Black or green, you will be demonized with equal vigor.

octagon · Post by **octagon** » Wed Sep 10, 2014 11:15 am

True. I just bought it in case someone was gonna tell me I couldn't have one. I'd rather have a Winchester 101 in 12g, what can I say, some days I'm just not that smart.

Mescalero · Post by **Mescalero** » Wed Sep 10, 2014 11:35 am

How odd............. I want a 101 in 20 ga.

Malamute · Post by **Malamute** » Wed Sep 10, 2014 12:03 pm

My dad has a 101, he calls it my gun, as its what I shot the most when I'd visit and we'd go shooting clays. It's a really nice gun.

I don't recall the exact details, but something was different about it. Like made in Italy instead of wherever else they were generally made? I think it has Italian proof marks, but don't think was marked Italy otherwise.

Griff · Post by **Griff** » Wed Sep 10, 2014 12:50 pm

Between my son & I we have 3 DI ARs, only two of which were purchased as complete arms... a Colt Competition 18" and a Wyndham 16". The other is a 24", with ports positioned appropriately positioned. All are now using the JP Captured Buffer.

It may or may not be an improvement, except in the noise department! It's quite the reduction!

I have receivers for two more, and have yet to decide what make of them... but I can guarantee that they'll be DI systems and have JP captured buffers. I see no reason to build a piston gun when literally millions of the DI guns are out there and working.

I'd pretty much listen to MrMurphy & 7.62 as their more recent experience far outshines my limited experiences from almost 43 years ago! Even if I remember half of what I was taught back then, the one thing that sticks in the ol' noggin', is to listen to the guys just back from the field.

Panzercat · Post by **Panzercat** » Wed Sep 10, 2014 1:56 pm

7.62 Precision wrote:The thing is, caliber discussions are one thing, since many calibers overlap and do the same things as well as other calibers.

On the other hand, the piston AR discussions are almost always fueled by misinformation designed to sell you stuff you don't need. The problem with researching it, is you turn up so much misinformation that takes some work to separate from the truth.

If I was buying a piston rifle, it would not be an AR, I would get something designed around that type of action.

No, I'm pretty sure this is exactly like caliber wars. Where somebody will post a benefit, the other will post a con to support their device of choice and it goes back and forth each thinking the other couldn't possibly be right. This happens enough on other forums to be unmistakable. 9mm vs 45acp. Apple vs Android. DI vs Piston. Etc Etc.

Of course you have to do your research. Be intelligent about it. Don't get all your information from one-sided sources who are in the tank for one or the other. But honestly, a piston on an AR is fine. There are enough manufacturers out there that didn't go under attempting to make it work and are thriving. There may be other perfectly valid issues you have with a piston AR, but that isn't one of them.

AJMD429 · Post by **AJMD429** » Wed Sep 10, 2014 2:54 pm

Griff wrote:I'd pretty much listen to MrMurphy & 7.62 as their more recent experience far outshines my limited experiences from almost 43 years ago! Even if I remember half of what I was taught back then, the one thing that sticks in the ol' noggin', is to listen to the guys just back from the field.

Makes sense to me...

piller · Post by **piller** » Wed Sep 10, 2014 3:03 pm

The blanks that we had back in the day, they seemed to use a different and dirtier powder. With the proper powders and a good lube, we never saw a malfunction from the M16A1 or M16A2. I heard about the problems with the wrong powder back in the beginning, but that had been solved a long time before I was an Infantryman. I was never in combat, so I don't know how that would affect things.

MrMurphy · Post by **MrMurphy** » Wed Sep 10, 2014 7:52 pm

The 'newer' blanks weren't much different. They use a coarser powder (just from observation) in an effort to be cheap. Malfunctions just= good training right?

I've shot the older generation blanks in the mid 90s and the 'newer' stuff around 2005-2007 and as long as you kept the rifle lubed, even the blanks wouldn't choke them much.

I remember in '96, in a pouring rainstorm at Knox, low crawling through about 30 yards of mud with an M16A2, going through a barbed wire pit which had become a barbed-wire lagoon (my mouth and muzzle stayed out of the water, nothing else did) and various other obstacles. Even after a swim and heavy mud caking the gun, even with blanks, I think that M16 had maybe 3 malfunctions in one magazine. Considering mud, heavy rain, submersion, blanks, and not much lube, I was surprised the thing fired at all.

RKrodle · Post by **RKrodle** » Thu Sep 11, 2014 2:34 pm

It's my understanding that a lot of the pistons out there are proprietary(sp), making things less interchangeable. I prefer the DI because for the KISS principle and the fact that they work with very few problems. I also prefer my AR's to be Colt, BCM, or DD. There are others that are as good or better but it's hard to beat the 3 I mentioned. I do have a Spikes, but I have it set up for P dogs. I also prefer a mid length gas system, the carbine gas system with a FSP is very cramped for my long arms. I wound up shaving the FSP on my Colt 6920 and installing a 13" Troy Alpha handguard to give me more room.

jeepnik · Post by **jeepnik** » Thu Sep 11, 2014 8:47 pm

7.62 Precision wrote:The thing is, caliber discussions are one thing, since many calibers overlap and do the same things as well as other calibers.

On the other hand, the piston AR discussions are almost always fueled by misinformation designed to sell you stuff you don't need. The problem with researching it, is you turn up so much misinformation that takes some work to separate from the truth.

If I was buying a piston rifle, it would not be an AR, I would get something designed around that type of action.

Something like a Springfield M1A? Closest we can get to an M14. I dearly love my Scout/Squad.

That said, the boys gave me a Stag with DI. Now, I'll never fire the number or rounds in a day that some have, but it hasn't given me any fits yet. In fact, I never had any problems with a M16 (original not A1) with regard to fouled tubes. It did tear the back part of a case one time, leaving the remainder in the chamber. Sucked at the time, but it all turned out well.

MrMurphy · Post by **MrMurphy** » Thu Sep 11, 2014 9:15 pm

The M1A actually has some issues with the number of cast parts now in use. The Fulton Armory model is a lot closer to a 'real' M14.

For the number of rounds typically fired in a noncompetitive match type user.....probably not a big deal. For a spotter rifle, DMR, etc......yes, it can be.

If I was going piston, and 5.56mm, if weight and availability was not an issue, I'd get a Sig 551, especially if it was optic compatible. It's an AK, built by the Swiss (more or less). Extremely accurate and robust. However...it's not light. The SCAR-L would be another excellent choice.

That, or a 5.56mm or 7.62X39mm AK with an optic added and a better trigger (which cures most of the AK's accuracy issues).

If I went bullpup, it'd be an AUG with a modern optic.

In 7.62, I'd get a OBR, if pure accuracy was needed, for a service rifle, a FAL, or better, a SCAR-H.

Streetstar · Post by **Streetstar** » Fri Sep 12, 2014 10:30 am

I used to be an AR hobbyist, And still have a couple stripped lower receiver's laying around I can build

I like the DI because of the interchangeability if you happen to have several similar firearms.

I sold them all with the exception of a retro build based on a Vietnam era Colt M-16 604 upper ----and recently procured a modern 6920 colt as well

I like the fact that all parts will interchange between the old and new rifles without a problem. I will never get enough rounds downrange to foul a gas tube unless perhaps I start taking multiple carbine courses back to back. ---- still I don't think that would do it

My experience with military grade hardware is not as current as Murphs and 762's seem to be, but we used both M-16 A2's and then ancient but re-furbed car 15's hard in mud, sand, wet weather, and anything in between.----not to mention our 203 guns were A1's that were at least 20 years old as well when I was training in the late 80s and early 90s

So I would go DI and not worry about it--- I would also venture a guess that collectively the members of this group take good care of our firearms and will likely shoot them just enough to spot problems before they become catastrophic

Personally, unless it is a hobby to you I would also go name brand like colt, Sig Sauer, ---and there are a couple of others. They AR 15 is not that complicated and I trust my home builds to an extent, but I also trust this new colt implicitly. But like any semi auto-half the problems encountered a magazine related, with another large percentage being related to bolt carrier issues----loose gas keys, little chrome rings lining up wrong and things like that.

But my thoughts are that if somebody buys a $700 rifle and then spends $200 more on a M-16 quality bolt and bolt carrier to ensure its reliability---- he or she is then darn close to the purchase price of the aforementioned colt or sig.

Grizz · Post by **Grizz** » Fri Sep 12, 2014 5:46 pm

Mike,

I don't have a 5.56. I've been looking and listening and the argument for the di bolt drive sounds OK to me now that I've had some time to think about it.

The $1067 Colt M4 at wallimart is calling. It ticks the right checkboxes for me but would expand the size of the caisson I have to lug around for re-supply.

Considering the anti-riot function suggested by the current group of looters I am also thinking hard about getting an ar or ak pistol, instead of a carbine. I have a 762 MBR if I ever get stuck in a main battle.

Grizz

MrMurphy · Post by **MrMurphy** » Fri Sep 12, 2014 7:39 pm

The AR pistol with the sortakinda stock thing is okay, but realistically, I've fit in places you never will with an issued M4 (29.75" collapsed) in armor...the 16" gun is only 1.5" longer.

A shorter gun is handy, but if I can cram myself at high speed into a C-17 cockpit, you can fit one into a car.

3leggedturtle · Post by **3leggedturtle** » Sat Sep 13, 2014 10:46 am

casastahle wrote:
FWiedner wrote:
Malamute wrote:I think the piston guns are over rated...
I'm on this page.

At least you're on a page.
I was well past halfway through this thread before I
realized the topic wasn't about air rifles

+1 that's a good'un

Malamute · Post by **Malamute** » Sat Sep 13, 2014 7:56 pm

MrMurphy wrote:The AR pistol with the sortakinda stock thing is okay, but realistically, I've fit in places you never will with an issued M4 (29.75" collapsed) in armor...the 16" gun is only 1.5" longer.

A shorter gun is handy, but if I can cram myself at high speed into a C-17 cockpit, you can fit one into a car.

True enough, though some of the question arises from the legal difference between a rifle or pistol and having it loaded in a vehicle. The carbine is more practical to use overall, but hits the snags with the legal parts, and how they have to be carried in a vehicle to be proper with local ordinances, as well as being legal in some places where "assault rifles" aren't legal to have. SBR's (short barrel rifles) also have legal snags, they cant be taken to some states at all, and fall under the same rules as rifles for legal vehicle carry. The not quite a shoulder thingy just opens doors that aren't as easily available with other options, but gives much of the same utility.

hfcable · Post by **hfcable** » Sun Sep 14, 2014 12:11 am

Chris83716 wrote:Piston is a solution in search of a problem. Lube and good quality ammo/ magazine are the solution to 99% of the "problems" with AR's.

Chris

well put....exactly.

jeepnik · Post by **jeepnik** » Sun Sep 14, 2014 6:08 pm

hfcable wrote:
Chris83716 wrote:Piston is a solution in search of a problem. Lube and good quality ammo/ magazine are the solution to 99% of the "problems" with AR's.

Chris
well put....exactly.

Hmm, paraphrasing the good Colonel I see. But, you are correct and it applies here as well as it did to the double action semi auto pistols.

firefuzz · Post by **firefuzz** » Mon Sep 15, 2014 7:56 am

MrMurphy wrote:The AR-15 was designed to be a DI (direct impingement) gun specifically to be simple and keep the weight down. Stoner was a Marine rifleman, 'grew up' on the M1 Garand. If he'd wanted a piston, he'd have put one in.

............

Piston ARs tend to have issues with carrier tilt and parts wearing in places they weren't meant to, because the parts were never designed to work with a piston and the different pressures they exert in different places.

IMHO, and I've build at least a few dozen AR's, if you want an AR get a DI gun, if you want a piston gun buy one that was designed that way from the ground up.

Another thing that I've never seen mentioned in the DI/piston arguments is that if you look at the gas travel route in the original Stoner design the gas moves from the gas tube into the gas key located on the top of the bolt carrier, then into the bolt carrier body, pushing against the rear of the gas rings, HOLDING THE BOLT FORWARD AND PREVENTING IT FROM ROTATING UTIL IT'S PULLED TO THE REAR BY THE REARWARD MOVEMENT OF THE BOLT CARRIER. This allows the chamber pressure to drop somewhat allowing for easier and more reliable extraction. Not only is bolt tilt an issue in piston conversions guns there is no gas pressure on the rear of the bolt to allow for this.

Precision 7.62 pretty well covered the rest of the issues, again IMHO the most important....proper lubing of the AR system. On any AR I build I fire the first 50 rounds thru it and I run the guns very wet and fire them very slow to allow moving parts to "mate" and the throat area of the barrel to "season". After that they are cleaned to bare metal and properly lubed before anyone else touches them. Never had a problem with any gun I've built that wasn't ammo/magazine/lube related.

If your really worried about carbon build up in the gas tube, and it can happen with ammo reloaded with a powder never intended for use in an AR or use with blanks (why would any civilian fire blanks thru their rifle?) a couple of blast of carb or brake cleaner down the tube, followed by dry air, at the beginning of the cleaning process will cure the problem.

Just my $.02

Rob

Old Ironsights · Post by **Old Ironsights** » Tue Sep 16, 2014 7:40 am

firefuzz wrote:...
IMHO, and I've build at least a few dozen AR's, if you want an AR get a DI gun, if you want a piston gun buy one that was designed that way from the ground up....
Rob

Won't argue with this at all (except in the aforementioned SBR context). But then, as a matter of preference, I'm not an AR guy anyway, so...