Paper and Lube Rings in Chamber

[303Guy]

68542

Rings left attached to the case mouth upon firing, both lube and paper. I'd found lube rings before but not still on the case mouth.

68546

Not to be confused with this one - this is the patch tail. The top one is also the patch tail but from a tail-less patch. It's the bit that sits over a small rebate in the boolit base. Both the lube and patch ring appears to be forming in the gap between the case mouth and throat start. I've found other rings inside the case neck and in the test tube but never left in the chamber but that could happen. So it seems I will have to abandon the tail-less patch in this particular rifle. That bottom ring was recovered in the test tube. There's an upside to it - I'm still struggling with wet patching so the short skirted patch provides a place to apply glue.

I still haven't been able to determine whether the patch tail ring on the boolit has any effect on accuracy - just haven't been able to do any testing for quite a while.

[bigted]

303,,,just a dumb question...are you sizing your brass to the boolit or loading a boolit patched to the throat diameter>>> [the fire formed case neck diameter] ? my lube and paper rings all but disappeared after beginning to load with "throat size" boolits instead of the bore or groove diameters. also I do know that a short case for the chamber will cause this to happen as well.

just a couple thoughts from the peanut gallery...LOL...[smilie=s:

[303Guy]

Those were with boolits sized to a fire-formed neck. As far as I can remember this only happens in one gun and is the width of the clearance between case mouth and chamber end.

[Westerner]

Mornin gents,
I shoot a Pedersolli Quigley Sharps in 45-70 using 400 grain swaged pure lead bullet with straight walls and a step shoulder "bore sweep" design. When I started out I put the paper to the shoulder and seated to touch the rifling. I had a ring of paper left at the start of rifling and the bullets flew off the map and I couldn't find any of the paper on the ground. I read Paul Greens book on PP and moved the paper just over the step down and the paper made a perfect form when it shrink dried and all was well after that. I do make the patch long enough to have a tail that I twist in the same direction of rotation and the patch comes off in tact. I also use a little case lube to the exposed paper. I size the patched boolit to the fire formed case and swipe the patch with a touch of SPG lube. So far the 60 grains of Triple 7 and Win primers haven't performed to my liking but they do give me a 4 MOA group, much better than "where in the world did that one go"!

[nanuk]

303Guy, can you get longer brass?

[geargnasher]

Longer brass or ream the throat entrance to just over patched boolit diameter. Do a pound cast and measure the throat entrance to be sure, it will certainly rake off paper if it's smaller than the boolit. I've also had rings with weak paper at high pressure loadings, even with the gap around .003-5". 100% cotton Vellum didn't ring even with a .015" mouth-to-end-of-chamber gap, provided the patched diameter was at or less than throat entrance, and that was in the upper ceiling of pressure limits in .270 Winchester at full-on copper-jacketed velocities.

Gear

[303Guy]

303Guy, can you get longer brass?
Not longer brass, no. I have this case which was too long for one of my guns. It's only slightly longer than the one with the rings. I've thought off drawing a few longer for this particular gun.

69344

No excess pressure signs and no others that I've noticed. (I don't know where that impression came from).

I haven't done a throat slug but I have measured the throat and it is tight. The gun didn't do too well on the first range outing. I know the throat is too small for paper patching but this one is pretty accurate with factory bullets - 1.25 MOA all day long. I'll try a tougher alloy and stronger paper for the next round of tests.