Ignoring gas checks

[Bill in Oregon]

My understanding is that a bullet designed for a gas check can be fired with perfect accuracy without same. Is that your experience as well, assuming velocities are kept moderate?

[JohndeFresno]

I was curious about this myself. Checking out various entries in several reputable forums - posted by folks who appear to have been there for quite a while - the answer has always been "depends upon the velocity" or "make sure your bullets are sized properly." But other than these provisos, no information indicates that there would be any problem using gas check cast bullets without the GC's.

That is, providing that you load them slower than you could with the gas check, of course.

I am admittedly speaking from online research; I have not yet tested this for myself.

On the other hand, you say "perfect accuracy." Since the base is not flush all the way to the case, if the bullet is not "perfectly" round at the base, I am wondering if that minute difference might not affect its initial upset somehow. That word "perfect" is pretty exclusive, especially if you are talking about minute of mosquito.

[Chuck 100 yd]

What John said +1 . I have tried it and will say accuracy was good enough but below that of the same bullet with a gas check.
PB bullets normally have a much wider base band while a GC bullet without the GC has a narrow base band and an unsupported "tail" that can funnel gases toward that thin base band. Much lower pressures will help prevent gasses from blowing by and causing leading.
Trying this yourself is the only way to know for sure if you can get by without the check in your load/gun. Have fun and let us know how it worked out.

[Tycer]

What they said. The bullet needs to fit the bore.

[Leverluver]

Also depends on how well the rear of the last band fills out and all the issues that may cause it not to; such as mold in question, alloy, temp and proper handling (or lack thereof). Anything the screws up the base of a bullet does nothing for accuracy as the gases at the muzzle will want to exit at the flaw first. Without the gas check, the rear of the last band becomes the effective base. Any flaw for any reason and accuracy will be poorer than with a gas check.

[Ray]

Deleted.

[Griff]

I would say the thickness of the last driving band would be the fly in ointment... but, that kinda flies in the face of logic. As any occlusion in the base will be the cause of both leading and accuracy. I do know from personal experience that velocity exceeding the alloy's ability to withstand such flame cutting is the deciding factor. I keep my stepped bottom bullets gas checked. And with my particular alloy I can then drive them as fast as jacketed bullets.

But, trying it out for yourself is your best test in YOUR rifle.

[jhrosier]

I shoot .50 cal cast bullets from my .500 S&W Handi Rifle without checks.
Reason being that checks are an unwanted expense.
I punch 1/2" disks from polyethylene and put one under each bullet.
My case full load of 777 keeps the disk against the base of the bullet.

Jack

[BenT]

The 115 gr .313 ranchdog bullet shoots just fine without gaschecks. I shoot it in the 327 FED and keep them sub sonic and work great for plinking.

[Sixgun]

I've done enough experimentation with that issue through the years that I cannot pin it down to any one thing. There are many contradictions of my experiments that make no sense like......if leaving the check off and leaving the last band to do the performing then why do bevel based cast bullets or boat tailed jacketed bullets perform the same at any velocity...excluding velocity/alloy differences?

I do find that the condition of the crown of a rifle has a lot to do with whether a bullet with the check on or off....but that's not the fault of the bullet.

I find that gas check designed bullets without the check on will shoot better out of any rifle with velocities in the 800-1000 fps range than with the check on no matter the condition of the crown. Make sense????...no

There are no set of rules or rules of thumb concerning whether or not you use a gas check or no check on a gas check designed bullet.

I have loading manuals going back over a hundred years that say "this or that" concerning this issue on gas checks.

The only rule of thumb I can say that is definitive is you just have to do what I have been doing for over 40 years.....experiment.-------6

[earlmck]

If I am going to be shooting the bullet at 1200 to 1300 fps or slower I leave the check off.

[Rusty]

I think experiment is the name of the game as Sixgun said.

I've read that gascheck loads should always be fired above 900 FPS to make sure the gascheck doesn't come off. I just take their work for it on that as I don't want any surprise bore obstruction.

I used to have a Lee mold for a 210 gr. SWC that shot fine at 1,000-1,100 FPS without the gascheck for my .41 mag. IIRC it had about 5 shallow lube grooves and a long bearing surface.
I also had a .357 mold that would throw a 121 gr. pointed bullet that wouldn't group in a washtub without the gascheck. I always thought the culprit on the 121 grain bullet was the short bearing surface. That was just an assumption on my part, I no way to prove it or not.

My rememberer don't work like it used to It's been about 45 years since I shot those.

[Bill in Oregon]

Thanks for the thoughts, guys. I will be shooting the Lee 325-grain 476 from a Bisley Super Blackhawk in .480 Ruger at 900 -1000 fps. Frankly, if Ruger made a push-through sizer in this caliber, I'd buy it and put on gas checks, but they don't, so I will see how this bullet shoots unchecked and report.

[mikld]

Yep to the above comments, but I would add that bullet hardness along with fit (most important) contributes to good check-less shooting. As long as the bullet ahead of the gas check step seals the bore, I figger it's good to go...

[Malamute]

Ive read several threads on castboolits forum, the conclusions seems similar. Most seemed to have decent results if velocity was kept reasonable. I was specifically looking for info on the Lyman 429215.

http://castboolits.gunloads.com/

[Ben_Rumson]

But if you have a rough bore as I do in my 1873 Win SRC there's not enough chamber diameter there to fit a proper diameter bullet. GCs allow it to shoot good without leading or very little.

We talk about leading being caused by gas blow by - flame cutting... How is it that a TP wad when examined after being shot is only singed when we know paper burns a 451*F and lead melts at a much higher temp?

[Blaine]

But if you have a rough bore as I do in my 1873 Win SRC there's not enough chamber diameter there to fit a proper diameter bullet. GCs allow it to shoot good without leading or very little.

We talk about leading being caused by gas blow by - flame cutting... How is it that a TP wad when examined after being shot is only singed when we know paper burns a 451*F and lead melts at a much higher temp?

Perhaps it's the exposure time....I can rapidly run my hand thru a Bernzomatic flame with little to no heat felt....

[Griff]

But if you have a rough bore as I do in my 1873 Win SRC there's not enough chamber diameter there to fit a proper diameter bullet. GCs allow it to shoot good without leading or very little.

We talk about leading being caused by gas blow by - flame cutting... How is it that a TP wad when examined after being shot is only singed when we know paper burns a 451*F and lead melts at a much higher temp?

Perhaps it's the exposure time....I can rapidly run my hand thru a Bernzomatic flame with little to no heat felt....

Or a cloth patch in a RB muzzle loader with BP behind it is only discolored. We call it flame cutting, but... it is really not pressure being released around thru the soft alloy, destroying the lube and leaving lead deposits from the increased friction?

[Ben_Rumson]

240 XTP.JPG

Aye! Increased friction! The pic shows a bullet I shot that clocked between 1100 &1200 fps out of my 1873SRC.. A .429XTP Note the lead that soldered itself on the inside of the jacket where the rifling bears on it during its semi milisecond ride out the 20" tube.

Edit Kind of makes me wonder how much friction adds to barrels getting hot.

[Old Ironsights]

...
I find that gas check designed bullets without the check on will shoot better out of any rifle with velocities in the 800-1000 fps range than with the check on no matter the condition of the crown. Make sense????...no...

Makes sense to me.

You are essentially creating a boat tail when you leave off the check.

Cast them oversize and hard enugh and they will pretend to be a JBT instead of a LSWC.