leading issues

[phishroy]

Im not sure exactly where to post this question.
I have been having some leading issues with my guide gun in 45-70.
Lead seems to build up in the first inch or so in the barrel after the chamber and the rest of the barrel is clear.
Im shooting 420 grain water quenched WW sized to 460 traveling at about 1200fps.
Lube used is BAC
Any recommendations where i should start making adjustments?
Thanks.

[Marvin S]

My guess is boolit is to hard for 1200 Fps. Can't think of what BAC is off the top of my head but it ain't that hard crayon stuff is it?

[phishroy]

its lars lube from this forum white label lube

[Marvin S]

It struck me as that after I posted, just to many acronyms in the world. Still think the lead is to hard.

[runfiverun]

the bac is fine the lead as marvin said is too hard.
and possibly a hair too small, i'd not waterdrop.

[waksupi]

Most likely the boolit could stand to be a thousandth or so larger in diameter.

[405]

Well, after the call-out and dress down of the general assembly on another "leading" thread, many may hesitate to give this a stab... including me.

?s What is the groove diameter of our bore? What is type of rifling in your GG bore? Are you over-crimping the case mouth? What inside diameter are you expanding the case necks to as it relates to bullet dimeter? What style of bullet? Is it gas-checked? Are you trimming your cases? Are you chamfering inside and outside the case mouth if you are trimming?

For what it's worth. I shoot all manner of 45-70s (from old trapdoors to old Win 86s to modern Sharps) without leading using bullets that are 10-12 BHN over both BP and smokeless to about 1200 fps. Bullets are gas-checked. Bullets are sized to groove diameter to max of .001" larger than groove diameter. I anneal the case necks. I use a neck expander about .001" smaller than the bullet. I don't crimp for the single shots. I minimally crimp for the tube magazine guns. Lube I use is fairly soft modified Felix with a dab of BAC.
Accuracy, I believe, is as good as these guns are capable of producing. No leading. I'd bet your groove diameter is something more like .457-.458"- as most modern bores are.

Good luck

[Moonie]

If I remember correctly aren't the guide guns micro grooved? Don't the micro grooved barrels prefer +.002 over groove?

[phishroy]

my guide gun is not micro grooved, its the other type which forgot what its called.
the BHN of my bullets is about 12 to 13 after i tested with the lee hardness tester.
the bullet is a magma mold bevel base 3 lube groove 405 grain from their catalog.
i use a lyman neck sizing die, i dont use a full length sizing die.

i do put a crimp on it in the upper crimp groove of the bullet.

i notice layers of leading only in the first part of the barrel after the chamber and the rest of the barrel is clean.

[geargnasher]

I have a hard time swallowing that your Water Dropped WW boolits are only 12-13, mine are at least that hard air cooled and aged for months. You must have tested them right after you cast them, or diluted the antimony some, or are using a lot of stick-on WW that are very soft.

Give your WD boolits a full week minimum to harden before testing, otherwise they will be harder than you think.

Some will argue that leading in the first part of the barrel is due to undersized boolits which "bump-up" after a few inches due to the pressure and at that point obturate the bore (seal) and quit gas-cutting and leading the rest of the trip down the pipe. I can't back this up with scientific tests, but I think it's probably right. If you can get those boolits a bit bigger and the leading quits, then you know that was right.

Bottom line, fit the boolit to the gun, and make sure that fit doesn't get screwed up when loading, crimping, and firing.

Gear

[Moonie]

I certainly don't dissagree with what geargnasher said but also you didn't say what powder you are using. If the boolits are plain base and you are pushing them with a fast pistol powder they may be stripping when they first hit the rifling. You can try a bigger diameter boolit and a slower powder. Check and see if the leading is on the leading edge of the rifling only, this will indicate the heavy boolit is having an issue beginning to twist because of too high an initial velocity when they hit the rifling. Just a thought. Normally gas check boolits don't do this as much as the harder check will help with starting the twist in the barrel and prevent the stripping.

[44man]

Has anyone thought to ask what powder is used?
Sounds like fast powder and a hard thump at the start with skidding boolits.
Lar's BAC is a fine lube and it does not look like a lube issue.
The boolit is too soft at 12 to 13 for fast powders. Water dropped WW's should be 22 BHN. Mix in all of the stick on weights and you have soft lead.
Why is the standard answer the boolit is too hard?
It is not hard enough for the forces applied.
Use slower powder or harden those boolits to take the stress.

[phishroy]

im using 23 grains of IMR 4227 if this info helps.
i trid measuring some of the bullets and i noticed that some of them are out of round, some measure 460 at one part and on the axis they measure almost 457.
it think that may be it. im surprised to see this sine they were all lube sized to 460?

[geargnasher]

im using 23 grains of IMR 4227 if this info helps.
i trid measuring some of the bullets and i noticed that some of them are out of round, some measure 460 at one part and on the axis they measure almost 457.
it think that may be it. im surprised to see this sine they were all lube sized to 460?

What makes you think your sizer makes undersized boolits bigger?

Gear

[Marvin S]

Mold is probably out of round. I find the super hard boolit thing is often highly over rated particularly at lower speeds. I do shoot the 45-70 in a 1886 SRC and also a 43 Spanish rolling block which is very similar. The 43 gets a boolit sized .002 (smaller) than groove dia because that is all the bigger that will fit without turning the case necks. The boolits are dead soft and pan lubed with bee wax,vaseline and a touch of paraffin wax. Powder is XMP5744 @ 27gr.Despite all of the things that are supposed to be wrong it shoots well without a trace of leading.

Rimfires don't use glass hard boolits.

[geargnasher]

Mold is probably out of round. I find the super hard boolit thing is often highly over rated particularly at lower speeds. I do shoot the 45-70 in a 1886 SRC and also a 43 Spanish rolling block which is very similar. The 43 gets a boolit sized .002 (smaller) than groove dia because that is all the bigger that will fit without turning the case necks. The boolits are dead soft and pan lubed with bee wax,vaseline and a touch of paraffin wax. Powder is XMP5744 @ 27gr.Despite all of the things that are supposed to be wrong it shoots well without a trace of leading.

Rimfires don't use glass hard boolits.

More evidence that dead-soft, undersized boolits DO swell up to obturate the bore when fired.

One thing commonly missed about .22 rimfire it that the velocity is well within what we would normally expect soft lead boolits to be able to do in most centerfires. The other thing is wax lube that .22s have also functions reliably and accurately at those lower velocities, and the PSI on the little sealing skirt is very minimal due to caliber.

Gear