Gas checks

[Norminator]

I shoot a 415 gr cast bullet at 1800 FPS. I tried 2000 FPS but it was a little hard on the shoulder.
Anyway, I seem to have great accuracy from my 26" barrel, and no leading. So what is the "rule of thumb" for using gas checks? I use an almost full to capacity load with a 45 cal wad of indoor outdoor carpet over top. Any and all opinions welcome.
Norm

[gcrank1]

I will be no help. My ROT is to not use a load that needs them so I stay quite a bit slower. My loads do what I want/need, maybe not what you want. IIRC somewhere over 1600fps (though for my 'GarageAlloy' of mostly WWt. I might say 1450fps) might have been mentioned in some old references, but it will depend upon alloy too. Ive read good things on 'Poly Checks' as being effective and WAY cheaper than copper.

[petemi]

I don't shoot a lot of cast bullets, but the ones I do don't go past about 1500 fps without a gas check.  What's with the indoor-outdoor carpet???  Sounds like a bunch of junk left in the barrel to me.

Pete

[Norminator]

For some reason I don't seem to get any junk left in the barrel. I think I just got lucky. I've always lived in northern Ontario Canada. Not many well stocked gun shops. I thought I needed some filler to take up the space between the powder and the bullet, and also to protect the base of the bullet. To this day I am still not sure if either consideration was valid or not. There was no Internet and I didn't know anyone who reloaded. So I improvised with carpet wads. Bought a buffalo classic and chopped it off at 26" Cause I liked the length and feel of my NEF muzzle loader. Recrowned it with a sandstone on the end of a cordless drill. I was considering the benefits of shooting a lighter load when I ran into the question of whether to use gas checks or not.

[gcrank1]

I was wondering about that 26" thing.....FWIW, my UH 45-70 in stainless has a 24" and I like the 'balance' a lot; we are close to the same taste it seems.
Any load that dups the old black powder ballistics will do you fine (1250-1300ish); it has for too many years to ignore.

[mechanic]

You don't state whether you use black or smokeless, but in either case, with a #2 alloy you should be able to shoot trapdoor level loads without a gas check.  I have a hollow base 405 gr. mold, and I've shot bunchs at about 1300 fps.
 
Again, I don't know what powder you are using, if black or a sub I understand the need to fill the space, but if smokeless, just go to Trailboss and no wad is needed.
 
Ben

[Norminator]

You illustrate my point with regard to my isolation and access. I am starting to gleen more and more info from knowledgable people at various forums. I don't know what a #2 alloy is. I drop my ingots on the cement floor. If they thud they get saved for the muzzle loader. If they tinkle I use them for all my other applications.  I've been using 4895. Never heard of Trailboss before today. Have tried some pyrodex with little success.

[RPRNY]

The "rule of thumb" is at 1800 fps and faster, especially with faster and mid range powders, you want gas checks and > 20 BNH alloy. That said, there are many people successfully shooting softer alloy without gas checks (or claiming they do), but probably with slow burners. With a straight wall case, the slow burning powders don't seem to perform as well and you get ineficient or incomplete burns - though maybe 26" is long enough to avoid this.

Cast bullets want a lot of fossicking around to find that which works best for you; part of their charm.

What I can say is that gas checked at 1800, all other things being equal, you should be getting the bullet centered in the barrel and moving well. If you don't want to gas check, alloy hardness is not the only other part of the equation. You're in an area that is more art than science. Different lubes, seating depth, powder burn rates, bullet weight, design and diameter... they all play a role and, if you are so inclined, you can experiment quite a bit and may find a combination that gives you good un-checked performance. Me, I gas check anything over 1500 fps (which is very conservative and quite possibly unnecessary to the point of stupid) but that takes one variable out of the equation.

[gunther66]

Now if I could just find gas checks.The 30 cal ones seem to be nonexistant.  G66

[gcrank1]

Try the Poly Checks or make your own; punched or better yet 'spun' out on a drill press of LDPE sheet at groove dia or up to .004 larger, depending on caliber. Ive read of guys using 'milk jug' type poly or other things you might find around home, shop or the building center. IIRC .020, .040 and .060 are good thicknesses.

[Catshooter45]

The only 'rule of thumb' I pay attention to is results.  Is the load leading?  Is it accurate enough for you?  Does it have the power level you want?
 
Gas checks only function in life (other than to suck a bit more more to shoot) is to stop leading.  Period.  If you don't have leading with checks you're good to go in my book.
 
It's results that count.
 
 
Cat

[gcrank1]

Or, if you dont have leading without checks, you're good. Load 'em up until you detect leading and back off a tad or use checks. I've shot rebated heel bullet designs for checks without same and at my velo, with my alloy, and a bullet dia. that fits the fully fire-formed to chamber case neck had no leading to speak of.
YMMV

[watkibe]

Hornady makes all gas checks in the US. Lyman buys from Hornady and resells them.
The real deciding factor is whether or not the bullet is designed for checks or not. In my experience GC bullets shot without the GC gives terrible accuracy; it makes sense, think about what the base of the bullet looks like to the expanding gas. On the other hand, you can't put checks on a bullet that is not designed to use them.
My basic rule is that no handgun bullet needs checks, and all rifle bullets do. The only exception is my 458-405-HB (hollow base) cast bullet.

[gcrank1]

Did you shoot those GC bullets, sans GC, at suitable for PB velocity? For me, if the bullet dia fits the critical throat and the base base isnt too skinny they work OK. I dont shoot cast bullets to try to get speed anyway.