Aluminum check problem

[tomme boy]

OK, I tried some aluminum checks today for my Mosin. This is a newer gun to me. I have been playing with it for about a month now. I have not been able to get anymore copper checks as everyone is sold out. Now I am getting leading all over my muzzle. And they shoot like garbage. These are seated below the neck. I have not had this problem before.

As I was working on some loads this morning, I was get fliers that would go 12-18" away. I am wondering if the checks are coming off. That might explain the leading and the fliers.

Anyone care to share their experience with the aluminum checks?

[JeffinNZ]

What is the gas check shank diameter? What thickness material are you using. What is the final sizing diameter of the boolit?

[tomme boy]

I bought the checks from someone. The shank is supposed to be .284" and they are being sized to 0.314" It is this mold. I had this made for one of my other Mosin's that had a very worn throat. http://www.accuratemolds.com/bullet_detail.php?bullet=31-205B-D.png

I can not pull them off with my fingernail. I measured them and they are 0.0145" and I measured the checks from Blammer and they are 0.0175" So they may not be holding on.

[Ben]

tomme boy

As I was working on some loads this morning, I was get fliers that would go 12-18" away.

Might we ask, what was your load ?

[tomme boy]

21-23gr of 5744. The boolits were lubed with Tac1 in all but the last grove. Then they were tumble lubed in alox. They were leaving a round hole when they hit so they were not unstable. Crown looks good, lube star was evident. But there was also flakes of lead fused to the muzzle. It was like it was in layers. The bore is like a mirror. I can see no pitting anywhere in it. The lands are nice and sharp. This one was not shot much at all.

When I got it home, I cleaned it. I took 3 passes with a brush and 3 patches and it was clean. So I don't know where the lead is coming from.

[tomme boy]

Anyone?

[plmitch]

I have been using only aluminum gc in my mosin, mat range from .011 to .014 and have had no problems with them.

[DukeInFlorida]

1) Slug your barrel to find out what diameter that is. It could be almost anything from .308 - .316" in size. You need to size your boolit to the slugged bore diameter.
2) Size your boolits .001" to .002" over slugged bore size. Only some experimentation will tell you which works better for your gun.
3) I suggest that you use straight wheel weights as your alloy, and water drop them.
4) Read: http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m for more information on that.....
5) The double lube that you are using MIGHT be ok. But, you might also consider using some alternative lubes, known to work better with higher speed bullets.
6) Read: http://www.lasc.us/Fryxell_Book_Chapter_5_Lubrication.htm for more information on that....

You would be well served to read Glen's entire free book. It will help you with other things that you haven't even bumped into yet.
You should especially read the chapter on gas checks:
http://www.lasc.us/Fryxell_Book_Chapter_10_GCkorPB.htm

[tomme boy]

The barrel is 0.3126" The alloy slips me right now, I use in it my 308 win at 2200 with no problems. The lead all over the muzzle is what is getting at me. It did not do this when I used some copper GC's. It might not just like this powder. Being this is seated well below the neck, I'm thinking it is blowing the GC off before it leaves the barrel.

[Dthunter]

Its just a guess, but you may have gasses blowing past your bullet before the base of the gascheck seals. This could spray/wash some lead & lube off the side of the boolet and out the muzzle before the bullet.

Try to recover a few boolets To see if this may be happening. This would explain tje loss of accuracy. But bad leading "USUALLY" accompanies this condition.

Try a few smaller charges of the same powder to see what happens.

I usually start low and work my way up. At some point my accuracy usually drops off dramatically.

Every powder/bullet/lube/gascheck has its limitations when pushed by a given powder. You may have just found Your combinations over pressure limits.