when to use gas checks on cast bullets?

[Bull Nutria]

I inherited hundreds of 45-70 cast bullets about 390g, some already lubed. My deceased uncle had cancer, he couldn't work so he spent his last months casting bullets and reloading with his Lee hand loader(without a press). I found a can of FFF blackpowder with the bullets,primers and loaded rounds.

I would like to reload 45-70 with modern smokeless powders and would like the to know the rules of thumb for when a gas check is necessary?

does a cast bullet have to be cast with a groove for the gas check or can a gas check be applied to any bullet. I have his dies and could give you the die number if you need it to answer this question.

Bull

 

[Slamfire]

Ninety nine percent of the bullets I shoot are commercial cast bullets without a gas check.

There are those with vastly more casting experience than I, but I tried casting 30 caliber molds, and they were set up for gas checks. The end of the bullet was recessed for a gas check. I tried shooting these without a gas check and the accuracy was awful. Accuracy radically improved when I put a gas check on.

So I am going to say, if the base is recessed for a gas check, use a gas check. If the base is not recessed for a gas check, it is un necessary and probably impossible to put a gas check on.

I used AA5744 in my Blackpowder era Martini Henry. This powder works well in the 45/70.



45/70 Martini Henry

26" Shilen Barrel


405 LRN 26.5gr AA5744 R-P cases WLR
29-Apr-04 T = 80 °F
Ave Vel = 1294
Std Dev = 14
ES = 40
Low = 1274
High = 1314
N = 15


405 LRN 27.0gr AA5744 R-P cases WLR
24-Mar-04 T = 70 °F
Ave Vel = 1284
Std Dev = 23
ES = 80
Low = 1263
High = 1343
N = 12


405 LRN 27.5gr AA5744 R-P cases WLR
24-Mar-04 T = 70 °F
Ave Vel = 1323
Std Dev = 14
ES = 38
Low = 1307
High = 1345
N = 5

 

[Ditchtiger]

Gas checks can be placed on plain based bullets.
This fellow makes a die that makes checks from cans or other material.
They work very well.

http://www.patmarlins.com

 

[Chawbaccer]

My memorie says that if you are less than 2000fps out the muzzle a gc isn't necessary. If you are going to re-load, get a good manual for cast bullets and follow instructions as to a gc or not.

 

[Ditchtiger]

I'm using checks to get a uniform base on my handgun bullets.
Helps get more accuracy.
Makes the most difference for 9mm as it has shallow rifling.

 

[grubbylabs]

It has also been my experience that if your bullet is cast for a check then you need to have one. I have seen a few post that they had good results without them but I and a few others have not.

If you are using an older 45-70 ie: not a Ruger #1 or a Marlin 1895 then you need to make sure of what is loaded. The older guns are not meant to handle the pressures that the newer ones are built for.

Post a picture of a cast bullet and I can tell you if it is meant to have a gas check on it.

 

[Elkins45]

I've generally found that a bullet that has a rebated base for a gas check generally shoots better with one, but that's just in terms of accuracy. I haven't found it makes any difference in terms of pressure. Leading might accumulate a bit faster but I wouldn't swear to it.

 

[10 Spot Terminator]

Ditchtiger,

I am curious as to the method you are using to seat gas checks onto cast bullets without a gas check groove. To the original poster the concept of the gas checks is to reduce gas cutting ( blow by ) on the softer alloys as where most of the commercial cast plain based bullets are hard cast . If you seek to load softer bullets such as for hunting that mushroom easier or to load for the higher end velocities then gas checks are a benefit. They also provide a more uniform bullet base which in itself helps some in promoting accuracy. For plinkers or mid range or slower loads plain based bullets will be fine. Just as with jacketed bullets, cast bullets require the right bullet for the right job. If you increase the power increse the BHN ( Brinnell Hardness ) of your bullets and/or gas check. With reloading you get only as much out of it as you put into it. Is a great rewarding hobby ( addiction ) . Enjoy the ride....

10 spot

 

[Ditchtiger]

10 Spot Terminator, I'll get back to you in about an hour.
I have something to take care of.

 

[35 Whelen]

I've gas checked some of my plain-base .357 bullets. I made a tool to flare the checks then used my lubrisizer to put the checks on.

But to the OP, yes there has to be a rebate on the bullet for a gas check. Most 45-70 moulds are not designed for checks as most 45-70 loads don't need them.

35W

 

[Ditchtiger]

If you go over to Cast Boolits, there are video links showing how this is done.
http://www.patmarlins.com this tool can be bought for most common pistol calibers and 30 caliber.
Also 2 sizes for each caliber, regular or standard gas checks or a slightly larger check for plain based bullets.
I have the .358 plain base tool as it works with 38/357 and 9mm.
I'm using material that is .004 thick and seating them with a Saeco lube-sizer
My barrels don't lead with mag. lead loads, I just like the improved accuracy with the added check.

 

[snuffy]

A fellow caster sent me some gas checks he made with Pat Marlins check maker. They are the 35 cal for putting checks on non-rebated, plain base .357 cast boolits. I put some on some 125 grain plain based boolits I made from a lee mold. The boolits were already sized and lubed, ready to be loaded. They went on easily, looked like they should work. I haven't had a chance to load any, so I can't report on how well they work. These were made from aluminum soda cans.

The checks are very thin and a bit bigger than the base of a sized boolit. The sizer die simply swages the base a bit smaller to accommodate the check. I use the Lyman 450 sizer for my boolits.

Definition of my spelling by 45nut, owner of the castBOOLITS forum;

Boolits= as God laid it into the soil, grand old Galena, the Silver Stream graciously hand poured into molds for our consumption.

Bullets= Machine made utilizing Full Length Gas Checks,(jackets), as to provide projectiles for the masses.

 

[Ditchtiger]

Hey snuffy, the soda can checks work OK though they usually come off and can be found 10'-15' in front of the barrel.
I have not noticed any difference in accuracy between checks that stay on or fly off.
Do you want to try a few brass checks form Pat Marlins check maker to try also?

 

[snuffy]

DT, thanks for the offer, but I'll pass for now. I want to get a GC maker from Pat, IF the ones I have work okay.

 

[35 Whelen]

snuffy, the Free Chex tools work well also. I had one in .30 caliber and made a jillion checks out of those aluminum "No Trespassing" signs. One $1.49 sign will make 500+ .30 caliber checks. I eventually made my own check maker that threads into a reloading press. Works great as well.

35W