Temporary insanity, leaded rifle badly

[singleshot]

Ok, I was playing around with loads in my 7.62x54R today. I ran across some load data in a Lyman book that suggested 20-30 grains of 4227 with a 200 grain cast gas check boolit. I started with 25 grains with my 193 grain CGC boolits. WOW! Within 5 rounds, I couldn't see the rifling for the last 3-4 inches of the barrel. Lot's of smoke! While cleaning, bristle brush didn't want to come out the end. I'm using 45/45/10 with 2 coats for lube. My barrel's been chopped to 16" specifically to shoot cast. This is the first time I've experienced this. The most I've ever used with this load is 18 grains with great results.

Is there any lube that could stand up to this load, let alone 30 grains of 4227?!?

[singleshot]

Oh I forgot to mention the boolit was a Lee C312-185-1R...

[94Doug]

Have you slugged the bbl? Seems there is a very large span of barrel sizes in the Ruskies.

Doug

[MtGun44]

Probably way undersized. since many M-Ns run .315 or more and for rifles you often need
groove diam +.002 or .003", so for many M-Ns this is up into .318, maybe more, not likely
from a .312 mold, but may be possible, depending on the mold.

You will likely have to beagle or maybe get a .323 (8mm) mold and size down.

Bill

[462]

Muzzle-end leading is most often an indicator of an ineffective lube, or not enough of it. Since you didn't experience any leading with the 18-grain load, your lube, or its application, is not up to the required task.

I don't tumble or pan lube so can't offer any alternative recipies or techniques.

[runfiverun]

re-check the pressure.
4227 gets squirelly when the chamber is hot.
the only time i have seen the grey poof is in an 0-6 with a nearly a case full of I-7828 and an oversized boolit nose.
but i didn't have enough leading to even get a brush out.
i'd say undersized, and over stressed lead.

[geargnasher]

Why did you chop the barrel to shoot cast? I find the longer barrels often work better because you can use a slower powder for a softer launch and still keep the muzzle pressure low while obtaining some impressive velocity (if desired).

Slug it and use a better lube. 45/45/10 is great stuff, but only for certain things. High-pressure smallbore rifle isn't one of them.

Gear

[1Shirt]

Had no problem with that pdr and that blt. in both of my Mosins sized .314, but have had better/best luck with 2400 starting with 16 gr and working on up slowly.
Ya, have to agree-----why did you chop the bbl?
1Shirt!:coffeecom

[runfiverun]

low muzzle pressure is condusive to accuracy at speed.

[singleshot]

Thanks to all for the responses! Yes, the barrel measures .311 nominally. I've had absolutely no leading with lower charges of 2400 and 4227, or higher charges of 4198 or Trailboss. I have to suspect the lube, or maybe the boolit itself.

I chopped the barrel b/c the most common powders I use in M-N rifles is 2400 and 4227. I've found the longer barrels don't gain me anything in velocity with my most-used powders, and the shorter barrel has proven more accurate (which I think may be an issue of barrel harmonics.) I normally shoot 16 grains of 2400 or 18 grains of 4227.

If I forsake Alox or 45/45/10 for higher pressure loads in this rifle, what should I go to? I think Gearnasher mentioned these aren't good formulae for higher pressure small bore.

Maybe before I jump to conclusions I should do some more testing in that rifle with my 160 grain Harris design tumble lube mold...

I actually shot that same "problem" load in another M-N I have that is a proven performer with .311-.312 boolits and had the same results...no more grooves at the end, but pristine grooves for the first 4/5 of the barrel.

Let me do a little more research and get back to you guys.

[singleshot]

The reason I chopped the rifle in the first place was a badly worn and damaged muzzle and crown...pitted, scarred, etc and ratty lookin rifling for the last 6" or so.

The reason I cut it to 16" is it's much handier that way...and there's some evidence to suggest I'm not gaining much after about 12-14" of barrel with the loads I shoot most.

I did try 2.5cc of Reloader 19 with good results (can't remember how many grains that was) but ran out of that stuff. I do remember a decent size fireball with that load...much better with a longer barrel no doubt.

[Wayne Smith]

I don't know that boolit, but if it is not a tumble lube, go to Speed Green, or any one of the other good high speed lubes Lars sells. If it is a tumble lube boolit - get another mold!

[44man]

re-check the pressure.
4227 gets squirelly when the chamber is hot.
the only time i have seen the grey poof is in an 0-6 with a nearly a case full of I-7828 and an oversized boolit nose.
but i didn't have enough leading to even get a brush out.
i'd say undersized, and over stressed lead.
Thank you, that is the first time someone else mentioned heat and 4227. The stuff drove me nuts in my .44.

[singleshot]

Thank you, that is the first time someone else mentioned heat and 4227. The stuff drove me nuts in my .44.

Hmmm...didn't Hodgdon marketed that as an extreme temp powder?

I noticed that now it's only in the IMR lineup and it says nothing about temperature sensitivity.

More current reloading data implies H4227 and IMR4227 were the same thing right before they discontinued H...

Anyway, this is NOT a tumble lube design, but I'm going to accomplish the same test with my tumble lube design and see if I get the same results.