Trouble with gas checks

[TrapperXX]

I have a new 4500, bullets cast from a LBT gas check mold (45-70) and new Hornady gas checks in 45 cal.
In order to get the gas checks to stay on, I have to really lay into the sizer handle. I mean I'm afraid I'm gonna break it. In fact, that is how the handle on my 450 broke. Some will stay on this way (70%) but some will not, (30%) no matter how hard I pull the lever on the sizer.
I tried the gas check tool that comes with the 4500 and it was no better. The checks are not hard to put on anyway, they wont stay on so I didn't think that would help.
What may be some of the causes of this loose check fit and what are my options? I had a couple come off in the case when I was setting up my new cowboy dies.
Now that I have the new dies this is the only thing holding me back from loaded rounds.
Thanks in advance.

[imashooter2]

Check retention is determined by the sizer die diameter, the boolit shank size and the thickness of the gas check material. Pulling harder will have no effect.

You can try a thousandth or 2 smaller on the sizing die, or possibly annealing the checks to eliminate spring back.

[retread]

I use as cast bullets in my 270. To seat the gas checks I use a Lee factory crimp die to clamp on the checks. Fill a case with lead that is trimmed to just below the crimp collet, file the top flat for the check to rest on, put the dummy case in the press and run the dummy up the die until it reaches the point just before it actuates the collet, seat your bullet in the check, then run to dummy up to actuate the collet and the check is crimped into place.

[Ben]

Most likely the gas check diameter of your mold is too small. You should not have to anneal factory Hornady gas checks if your gas shank diameter is correct.

You ( or someone you trust with good machinist skills) can open up the gas check shank diameter of the mold so that your checks are a " snap fit ".

I've made them larger with a split wood dowel with a piece of 320 sand paper wrapped around the dowel. Don't allow the sand paper to work out side the mold as it will " bell " the end of the gas check shank on your mold.

I use a cordless drill on super slow speed to turn the dowel. GO SLOW, you can remove metal, you cannot put it back on. You want a snap fit, so take out some metal , go cast 5 bullets, see if you've achieved that " snap fit ", trial and error until you reach the optimum point with your mold.

When they go through the sizing die after this modification, it will be near impossible to get one off the base of the bullet.

[TrapperXX]

Thanks guys
I measured a few bullets and the shank is 0.421
Using the tails of the caliper the inside of the checks is 0.426
Ben, I like your idea and might try it but will proceed SLOWLY. I don't want to ruin the mold.
Do you mean split in half or split in the middle to hold the sand paper but still round?

[Ben]

You should have a bullet with a .425 " or 426 " gas check diameter shank. At .421", it looks like you are a full 4 or 5 thousandths too small. No wonder they won't stay on.

Is this a new LBT mold ?

I'd be tempted to simply return this mold to LBT with a few sample bullets and a few of your gas checks. I think they would correct the mold problem for you.

Ben

[Ben]

TrapperXX

You asked about the dowel.
Here are photos of mine I use to enlarge
.30 cal. gas check mold gas shanks with, making one just like this for a 45 cal. rifle mold is no problem, you would just have to have the correct combination of wood dowel diameter and wraps of 320 sand paper to make a snug fit inside the gas shank area of your mold :

( REMEMBER - - DON'T ALLOW ANY OF THE SAND PAPER TO WORK OUTSIDE OF THE MOLD, ALL OF IT MUST SAY INSIDE THE MOLD, USE VERY SLOW RPM'S , CAST AND CHECK THE DIAMETER, REPEAT UNTIL YOU'VE REACHED YOUR GOAL )

http://img.photobucket.com/albums/v494/haysb/003-55.jpg (http://smg.photobucket.com/user/haysb/media/003-55.jpg.html)

http://img.photobucket.com/albums/v494/haysb/004-50.jpg (http://smg.photobucket.com/user/haysb/media/004-50.jpg.html)

http://img.photobucket.com/albums/v494/haysb/005-38.jpg (http://smg.photobucket.com/user/haysb/media/005-38.jpg.html)

[TrapperXX]

Ok, split in the middle. Thank you, I learn best from pictures.
Yes, I'm gonna contact him now, mold is brand new. Good idea. I'd rather have him do it than me screw it up.

[Ben]

Not likely you'd mess up the mold. A fairly simple procedure.

However, with a gas check shank ( on a brand new mold ) that is .004"- .005" too small , I'd think LBT would be glad to help you.

[imashooter2]

Not likely you'd mess up the mold. A fairly simple procedure.

However, with a gas check shank ( on a brand new mold ) that is .004"- .005" too small , I'd think LBT would be glad to help you.

Absolutely this.

[TrapperXX]

I think you both are right, Veral has been great to me so far.