Mauser Load Question

[Nelsdou44]

I tested some hard cast loads in a VZ-24. This Mauser has the deep grooves and wide lands. Boolits are sized for the groove depth, GC'd, alox lubed in the grooves and re-coated again. Weigh in about 190 grains or so. Using XMP5744, got wonderful accuracy at 23 grains (thanks Maven!), while testing 22-26g loads.

Next tried 27-31 grains of 4895 with a bit of dacron filler; got real sooty necks and accuracy fair. Next tried 28-31 grains IMR3031 with a bit of dacron filler; again got sooty necks but accuracy steadily got worse. By then I'd put about 60 rounds through the rifle.

Sure enough, although the bore looked ok, I got flecks of lead out during bore cleaning on the patches.

Now sooty necks tell me the charge is maybe too light, but I'm frustrated by the leading. I've used 4985 with good results in the 308. Could it be that I should increase the charge for 4895 and 3031? Or should I see if I get leading eventually from the 23 grain 5744 handload?

Nels

[Ben]

Nels:

If you mentioned the condition of the bore of your rifle, I missed it. If your bore is a bit frosted or has been subjected to the firing of corrosive ammo in the past without proper cleaning, that could be the culprit that is causing your leading.

Thanks,

Ben

[Nelsdou44]

Thanks Ben.

Yep, the bore has some minor pitting, but overall is pretty shiney with sharp lands. One thought is to shoot a number of 23g XMP5744 loads and see if those alone result in any leading. Darn acurrate and I could easily tell if the groups start to spread.

The other powders, I dunno. Just wondered if they weren't powerful to seal the case necks that maybe the bullets lacked getting enough pressure to engrave them fully into the grooves, and thus getting some blowby. If I can keep the accuracy with the 5744, I'll be happy.

Nels

[fourarmed]

Nels, if you are only getting "flecks" of lead out of your barrel, It almost certainly is not leading badly enough to affect accuracy. I have a revolver that shoots almost well enough with cast to be competitive in the international class of IHMSA silhouette shooting, and when I clean it after a match I peel out long strips of lead from every groove. I keep hoping that if I can eliminate the leading, I can eliminate the "almost." Probably you aren't getting high enough pressure with the 4895 and 3031 to make them burn uniformly. Increasing the charge may help. At least until the pressure exceeds what your boolit alloy can take without slumping.

[Ben]

Nels:

Have you slugged your bore and what size bullet are you shooting right now ?

Ben

[Topper]

One other thing that can cause case necks to soot is work harden brass. If work hardened, upon firing the brass may not be pliable enough to seal the neck portion of the chamber, allowing the hot gas to escape toward and into the chamber.

[Nelsdou44]

The light bulb just went ON! Just as I was depriming this brass, I noticed one out of the lot had a cracked neck. Annealing the necks I will go, eventhough I didn't get sooty necks from the 5744.

From a Cerrosafe cast I've got .329 grooves and .312~.314 across the lands. Right now I can't find or remember the exact dimension on the lands, but you can see this baby has deep grooves. I've shot .329 bullets made for the M-95 Steyers and they shoot very well. I keep a close eye on pressure signs and make sure I've got plenty of clearance in the chamber on the case necks shooting fatter boolits. Right now I'm shooting a .329 David Moss FNGC design, #2 alloy that's advertised at 175 grains but actually weighs closer to 190~195 grains.

Having the deeper grooves was why I was thinking my loads need to "spank" the boolit a bit harder to engrave and seal. The case necks not sealing may be an independent variable, but annealing will hopefully take care of that.

Nels

[Nelsdou44]

Got those case necks annealed and it did the trick. Last range session no more sooty necks.

23 grains of 5744 prints the 195 grain boolit into an inch at 50 yds. :-D However when I put the paper at 100 yds, the groups expand to 4~6 inches. I made a run using IMR 3031 and pushed it all the way up to 36 grains without leading the barrel but got the same results; excellent groups at 50 yds but 4~6 inches at 100 yds. Close examination of the 100 yd paper indicates no keyholing.

My guess is that this boolit is starting to loose stablization somewhere between 50 to 100 yds. My next thought is to bring the loads down (that worked good at 50 yds) to see if I can get it to group at 100 yd. A tight group at 100 yds is my goal as that is a more typical hunting shot for me.

Any suggestions?

Nels

[45 2.1]

Try a different group of powders and reduce your alloy hardness somewhat.