View Full Version : Loose gas checks?
03-31-2007, 04:47 AM
I just got a new lyman mold .457 diam. 475 gr. gas check. My problem is the gas checks are loose and fall off even after installing them with a sizer. I am using hornady crimp ons. I miked the base of the bullet and the inside of the gas check and there is a 5 thou. differance between the two. the bullet is the smaller. Do I have a problem, can I use them and if so how do you keep it on? the gas checks are a good fit with the other 457/ 458 bullets that I load.
Thanks in advance, Stubert
03-31-2007, 05:38 AM
Yes, you have a BIG problem. You have two solutions, send the mold to Lyman to get it fixed or lap the gas check portion for a snug fit. You do not wan't to lose checks when you shoot or have them fall off in the case.
03-31-2007, 05:39 AM
Since the gas check shank is too small, to at least have excess material in the mould.
Easier to remove than add so I feel you are lucky in that regard.
Were I you, I'd PM Buckshot and get his opinion on approaches to correct this problem.
Have you tried annealing the gas checks? Problem may be the checks.
That may be a very simple solution.
I'm currently trying to find some of my moulds I'm going to have Buckshot HP for me.
I'm sure others will be able to give experience and advise.
03-31-2007, 05:42 AM
are you sure your getting good fillout when casting. If your casting to cool or dont let the lead run in your mold for a touch after its full your gas check base may not be filling out properly.
03-31-2007, 07:46 AM
Mic the outside of the GCs after sizing. If they are much over what you are trying to size to, they are too hard and springing back. Annealing them will fix that. Also compare the shank diameter of the problem mould to the shank diameter of the bullets that are working with your GCs. If there is a significant difference, I'd lap the shank out a bit.
My method is just to chuck a bullet in a spare chuck, coat the shank with fine valve grinding compound and turn by hand. Do NOT use power.
There's one more possibility. If you are using spray mould release, that will cause bullets to cast small.
If the trouble is caused by an undersized gas check shank you could try this: Take a boolit cast in the mold, turn it upside down and insert only the gas check shank into the mold. Add a little fine valve-grinding compound and turn the boolit carefully to open up only the shank area.
Proceed very slowly and measure often.
I fixed a 6.5 mold in this manner with complete success.
Added later: (Leftoverdj and I must have posted a response at the same time. Sorry for the duplication.)
03-31-2007, 08:12 AM
I fixed it. I lapped the shank larger by 4 thou. Thanks for the the sugestions
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