Shaved lead building up in chamber

I am having an issue with my STI Eagle 5.0 45. It is the only gun I have that does this with any lead SWC's I have tried. I cast my own and use commercial tips. They all do it. After 10-20 rounds I get rounds that don't go into full battery due to a buildup of lead at the case mouths. If I take an unseated round out and examine it there is a thin ring of shaved lead from previous rounds packed around the tiny bit of tip shoulder protruding from the brass. I can run a bronze brush in the empty chamber and get a thin partial ring of lead out from the area at the case mouth. The gun runs great with plated or jacketed tips. Help please.

Try seating the lead bullets with the shoulder flush to the case mouth. 

Dave C.

My ring of lead left in the chamber was being formed on bullet seating. The seating die inside diameter was to small/tight, removing the flare to soon. This made a small ring of lead right in front of the case mouth when seating and taper crimping in the same operation.  Removing some metal/enlarging the inside of the die, fixed my problem.

a common occurance when seating and crimping at the same time.

Check this.

http://castboolits.gunloads.com/showthread.php?232061-1911-Throating

I've seen this quite a bit (lead shavings in chamber) and throating doesn't seem to effect accuracy. Doesn't cost much either to have done if you can't do it yourself.


Virgil

I use Dillon dies which seat and crimp in separate stations. There is no shaved lead at the case mouths. I have made this mistake before by not belling sufficiently. I will be making chamber casts of this gun and others tonight to see if there is a difference. It may be going to see my smith for a throating job.

The barrel is indeed throated as described above. The rifling is tapered as it should be. Dropping one of my rounds into the chamber revealed that the case head rests a few thousandths above the barrel hood. In other barrels the case head drops slightly below the hood. The depth measuring end of a digital caliper put it all in perspective. From the end of the hood to the end of the chamber measures .902". My Kart NM measures .020" longer! What is the spec for this measurement? I will be trying some rounds with my H&G 130's seated flush rather than with .020" of the tip shoulder protruding from the case.

Your barrel may be short on headspace.  Most custom fit barrels come short chambered.  After they are fitted and the hood is at its final length, they have to be headspaced with a chambering reamer.  Looks like maybe whoever fit your barrel may have failed to do this.  If memory serves me the max case length for 45 ACP is 0.898.  I don't know what a SAAMI GO gage length would be, but .902 is close.  Do factory jacketed rounds chamber fully when dropped in?

Some chambers need a .451" diameter bullet to chamber fully.  SAAMI drawing of a match chamber here.    45 acp   Headspace is .898" to .920"  see drawing at link.

You can probably eliminate your problem by seating the bullet a little deeper.

STI called me back and said their chambers are cut to CIP specs rather thanSAAMI. They make them .901-.904" deep. I will try seating my lead tips essentially flush with the case mouths. I will be shooting this gun Thursday in the PSA shootout with plated tips.

They are BULLETS, not tips!

Actually, I prefer "BOOLITS" since I cast my own and am a fan of the Cast Boolits website. I cannot warm up to calling them "heads" though. We seem to use "tips" more in the rifle lingo.