7.62x25 leading in 2 different CZ52s

[Black Wolf]

Gentlemen, time to pick the "pro's" brains.

I got 2 CZ52s that I've been shooting 100 gr cast WWs (water quenched) bullets through. BHN is 15.4 according to Lee tester. No gas checks (Plain Based Lee bullet). Lubed with Lee Alox. Powder is 4.1 gr of Titegroup. Velocity on my Chrony shows 1135 fps average.

One CZ52 has a groove dia. of .309" and I'm shooting .309" sized bullets in it - noted above. Other has .310"groove dia. and I'm shooting .312" sized bullets in it - noted above (although that'll be changing since some don't chamber due to a tight throat on these things - but that's another issue I can deal with). So, one being bullet being AT groove dia. and the other .002" over groove dia. - both leading (so that said, I doubt it's a bullet size issue).

Both are leading bore. In an effort to stop the leading I'm currently hardening in the oven some .309" bullets (475 deg. for 1 hr) and will see if that makes a difference in the leading. I'll also put a little thicker Alox on the bullets to see if that helps.

Suggestions...other than what I'm trying? (possibly slow the bullet down a bit? - but it's already on the lower end of the spectrum based upon Lyman load data).

[Doble Troble]

I'm not a pro brain by any means. Shooting cast in a 7.62x25 is a bold move! Here are things that I would do different:

1) The Alox probably isn't enough. I'd try conventional lube filling the grooves.
2) I'd size them all at 312 for both guns.
3) I'd slow down the bullet as you suggest, and maybe go to a slower powder.

[JonB_in_Glencoe]

In an effort to stop the leading I'm currently hardening in the oven some .309" bullets (475 deg. for 1 hr) and will see if that makes a difference in the leading.

I'm not expert in shooting cast boolits,
but I have been researching WW lead alloy.
I believe, and someone correct me if I'm wrong,
but annealing cast WW lead (heating at 400 or 475)
will soften the lead to the hardness of the day after cast.
cast WW alloy (that was air cooled) should age harden
over a six week period.

with that said, leading in a barrel is primarily caused by blowby
from under sized boolits.
of course Hot loads and lack of lubrication are surely other reasons
that shouldn't be over looked.
read some of Elmer Keith's experiences.
He'd shoot magnum revolvers with fairly soft lead.
Jon

[chris in va]

I had the same issue with my CZ 75. I know it's not the same gun, but still had lots of keyholing and leading with traditional 9mm boolits. I tried 4 different types to no avail.

Using a 38 Special mold sized .003 over fixed my problems. I also had to shorten the OAL down to 1.01, almost scary compared to what should be normal for 9mm. I also load to near minimum as anything hotter makes it skid down the barrel.

[Echo]

BW, we all assume that when you heat treat the boolits, you snatch them from the oven and drop immediately into cold water. Right???

My recommendation for autoloaders has been to size to the fattest that will reliably chamber in the gun. You have done this with one gun, and still get leading, so my guess is that the LLA is failing you, and you should try conventional lubeing, and leave the LLA to lower-intensity cartridges.

FWIW...

[autofix4u]

I also am no expert, but owning 5 cz52s at the moment and having had several others in the past all being shot with cast, I think i can help.
Most all of the 52s i have slugged show a grooves
of .311-.314, and shoot well with boolits sized at .312-.316. But i have yet to find one that will chamber a round with a slug that large in factory brass, the neck is too tight. So that leaves the options of 1 neck turning brass or 2 opening the neck of the chamber up. I chose #2 for all of my shooters.
Your second problem is powder choice. I feel that Tightgroup is too fast for the 7.62x25. you need to try something slower. I use wc820 (aa#9), H110 and blue dot, with H110 as my firs choice (since H108 is no longer avalible).
As far as slowing it down goes, dont do it. The cz52 needs a min of 1050fps to function reliably with the stock recoil spring and higher speeds with a heaver spring. I run most loads at 1250fps for plinking & target work and 1400-1600 for hunting.(1600 fps with a 100grn wwhp is my whitetail load have taken 2).
I also use LLA for all loads up to 1500fps, so i kn
know it can be done.
Open the neck of the chamber up or neck turn your brass and keep trying. Good luck & safe shooting, Josh

[Black Wolf]

BW, we all assume that when you heat treat the boolits, you snatch them from the oven and drop immediately into cold water. Right???

...so my guess is that the LLA is failing you, and you should try conventional lubeing, and leave the LLA to lower-intensity cartridges.

Yes - when I took the bullets out of the oven (versus water quenching them) I dropped them directly into a bowl of water with Ice Cubes. These bullets (having sat overnight) have a BHN of 20 (versus the former bullets which were 15.4). So, we'll see now if a little harder boolit (25% harder) and really putting some extra Alox on the bullet will keep the leading down.

To all (who've mentioned size of bullets), I have had intermittent reliability in chambering the bullets when they are sized to .312" - therefore, I cannot go any larger.

I'm gonna' run out now and give those harder bullets a shot and see if they lead any in the .309" bore CZ-52. Changing too many variables at once would be detrimental in determining the root cause of the issue. Next I'll try a slower powder (if I got anything that'll work - slowest powder for pistols that I have is 2400).

Side note, the necks of the cases have already been turned quite a bit having resized .223 brass to make the 7.62x25 - and necked turned them a bit already.

BRB - checking new bullets.

[NSP64]

Well what did you find???

[Black Wolf]

Ok - back.

The harder bullets (now 20 BHN) and more lube didn't help. However, I loaded up the harder bullets using 8.5 grains of Alliant 2400 and got a lot less leading. I only shot about 7 rounds but the leading appeared to be less. I'm gonna' do some shooting and also Chrony it to see what velocity it's moving at - seems lighter than the 4.1 grains of Titegroup (at least it FEELS lighter).

Anyhow - more to report coming (kind of in a rush - 4th of July party to start soon).

[Black Wolf]

Ok - back.

The harder bullets (now 20 BHN) and more lube didn't help. However, I loaded up the harder bullets using 8.5 grains of Alliant 2400 and got a lot less leading. I only shot about 7 rounds but the leading appeared to be less. I'm gonna' do some shooting and also Chrony it to see what velocity it's moving at - seems lighter than the 4.1 grains of Titegroup (at least it FEELS lighter).

Anyhow - more to report coming (kind of in a rush - 4th of July party to start soon).

Back now:
Chrony info of 8.8 gr of Alliant 2400 w/ a 100 gr WW/WQ boolit (9 rounds):
Hi: 1223
Lo: 1072
AV: 1172
ES: 151
SD: 44

Still had some leading at the end of the barrel (about an inch) but it scrubbed out pretty easy (just a few scrubbs with the brush). Before, with the Titegroup, I had to fire 3-4 rds of jacketed to get the lead out. Hmm.

[snuffy]

Well, I'll chime in with some limited info. I too use the lee 100 grn. RN in my CZ-52. I never slugged the barrel, may do that just for S&G. I dipped the bases in full strength LLA up to the top driving band. Set them on cardboard to dry. Then ran them through a lee .309 sizer.

I load them using WC-820. I've never tried any other powder, they're a hoot to shoot, large fireball and loud bang. As far as accuracy, they go into a group the same size as the J-word bullets with the same powder charge. That said, the groups are about 6 inches @ 25 yards. Same with factory stuff S&B and winchester metric loads. Even military stuff does no better.

I had to rig a fishing landing net to gather the brass. Got tired of chasing them, then ending up loosing 10-15%. Can't reload 'em if ya can't find 'em.

Oh, and no leading that I could see, or fouling that didn't come out with a .308 bronze brush and normal solvent.

[leftiye]

I'm thinkin' that Autofix had your answer - larger chamber neck (hand turn a chucking reamer of desired size in chamber neck. Desired size is groove diameter plus .001", plus case neck thicknessX2, plus .002" for clearance.) Then shoot boolits that are groove diameter plus .001 or .002". Leading in the last inch of barrel - probly lube running out. One other pozzibility, How big is the freebore (if any) between the case mouth and the start of the rifling? If it is oversized you can have gas cutting at that point. AA#7 is a purty good powder in the 7.62X25. BTW. I shoot a .314" 120 grain RNGC in mine. No leading, but the cases dissappear.:groner:

[Black Wolf]

I'm gonna' try pan lubing them today to see that makes a difference using the softer (15.4 BHN) bullets sized to .309".

I ordered another .309" sizing die that should be here this week. I plan on lapping that one out to .310-3105" and see if that will help.

Last shots I was able to just use my brush and clean the lead out of the barrel where as before I had to shoot jacketed bullets to clean it - it wouldn't scrub out with a brush for nothing. :-(

Based upon this thread: http://castboolits.gunloads.com/showthread.php?t=87774
...it may be "lead washing" that's in there now (not sure what that is). It scrubbed out pretty easy last shooting but boy, it sure didn't when I was shooting the Titegroup loads. Wouldn't come out for nothing.

[Wayne Smith]

I only have one suggestion, make your boolits and hold them for a month or so before shooting. I understand that they will reach their hardest in 1-2 weeks elapsed time and stay there for years.

[Black Wolf]

I only have one suggestion, make your boolits and hold them for a month or so before shooting. I understand that they will reach their hardest in 1-2 weeks elapsed time and stay there for years.

My bullets were cast last March...just as an FYI.

Side note: Today I shot 10 of the same bullets using 4.1 gr of Titegroup (the original load), only thing changed was the lube (which was a pan lube from this recipe: http://www.youtube.com/watch?v=bBDFO0ftCQc ).

Leading certainly was reduced to only the lands (not the grooves) and was easily scrubbed out with a brush. Last experiment that I'm gonna' try is to take the same bullets, lubed with pan lube, and then instead of using Titegroup I'm gonna' try the Alliant 2400 slower powder and see if it continues to decrease.

I know this may sound ridiculous posting all this but it sure helps in keeping my trouble-shooting orderly and maybe help someone in the future.