Zn/Cu alloy

[popper]

As this is an experiment, I'll put in it's own thread rather than clutter the other one. Purpose of the experiment? 1) to find an alloy that doesn't need heat treat that shoots good at high pressure. 2) find an alloy that meats #1 and isn't high BHN - not brittle and maybe some expansion. Add any results of other OPs if you want.
Results so far.
1) Shot 40sw close to top jacketed load pressure (~30K psi) using (percents are approximate - no XRF) using 0.3% Cu (max room temp solubility of Cu in Pb) and 0.15# Zn. AC & PC, no leading.
2) shot BO 170 & 185 (gc) with 4/6 ratio isocore/Zn mix. No leading no problems, BLL used.
3) Added more Cu and Zn - 0.5%/ 0.2% , same boolits in BO but I'll test with carbine.

 

[freebullet]

Sounds interesting. Be real interested what the alloy could do in rifles.

 

[fiver]

if he pushes the 300 like I have known him to it would be a good start at getting closer to rifle speeds that could be useful.
I don't think alloy is a substitute for fitment and load details, but a heads up test would give a good starting point to work from.

 

[popper]

Not as good as I wanted but a start. 18" 1:10 carbine. Alloy ~ 1%/0.5%/0.2% Sb/Cu/Zn 170 PB & 185 GC over 18 gr cfe blk, 3x BLL. ~30k & 45k psi, 1700-1800 fps, from Hornady load data. PB was mostly on paper @ 50, GC wasn't bad. Some leading in barrel, not bad. I need to try PC to see if same problem as 40SW, BLL blowing off. I did fire some half jacketed to clean the bore between sets. Ok not much breeze but hot & humid.

 

[fiver]

woah,, that's some vertical stringing.

isn't the CFE about 4198 burn speed?
I'm thinking you over-sped the plain base a bit but the gas checked ones should have handled it okay.
that vertical stuff is what you need to look at.
it could be the powder and velocity variations but they usually don't throw them that far apart [more like up then down then up] it looks a bit more like stringing.

 

[popper]

Fiver - target was rotated when shot so it's horiz stringing, probably me. Think my shoulder is moving under recoil. They were seated longer, GC in the neck and still feed OK from the mag. Did have to pogo one rnd, couldn't find it on the ground. Anyway, more Zn and I'll PC the PB to see if that makes a difference. PB were fired first. Got to go get some tires on her car for her Custer trip with daughter to meet the GKs at scout camp. I get to take care of the dogs.

 

[popper]

Opps, brain fart. PCd some PB this morning but used my normal sizer -308. no spring back so they are 308 vs 3085 normally. I'll do some more & size 309. Target holes are round for the 40 & the 30 PB but boolits are undersized. Maybe the reason for lousy accuracy.

 

[fiver]

hmm.
I'm still on the fence about oversized bullets.
I have done well with groove size in many situations and not so well in others.
I'm sure it has to do with the throat and bullet shape relationship, but haven't quite put the workaround together.

 

[popper]

Never slugged the barrel on either BO, but 3085 works fine with hard alloy. Interesting that accuracy is better with GC than without, cfeblk is supposed to be very low pressure powder, I specifically used it here for testing soft alloy. I'm assuming the BLL coated (0.001) gets blown off by the undersized and results in failure. GC either keeps spin up and/or reduces the blow-by. Looked at the targets with mag. yesterday, very slight tipping with the PB, none on GC. Interesting if we saw some pressure traces of cfeblk vs 1680 or H1110. Anyway, next test is PC 308 & 3085. PC solved the keyhole prob. in 40 but accuracy wasn't great. Just remembered, I do have a Lee 401 I honed out when I was (by mistake) trying Pb/Sn a few years back. Also have some boolits left I can see how undersized they were. After I find something that works I need to find a place so I can see terminal results on the low and high (~36) BHN.

 

[popper]

Tried to shoot the PCd stuff this morning in the rain. Didn't get many off, tried the 145PB & 170 PB. The ones I got off did fine, round holes and~4" group. Alloy is soft so seating expanded the nose enough that they wouldn't chamber right. BLL seats easy, PC doesn't. Got a few stuck. But no leading! Guess I'll melt down the 145s i cast and stick to 30/30 for testing.

 

[fiver]

does time give any more hardness?
or is it just the 2 week wait and you get what you get.

 

[popper]

Fiver - haven't checked harness with time. Stumped now. Poked the stuck boolit (less case & powder) out of the chamber - base band dia. is LARGER than front (that goes into throat) band by 0.001!! Measured base and front unscuffed part of the bands. Necks turned to 0.01", not a compressed load, no setback. strange. These were PCd a day before shooting and AC but no way the base can grow without the nose also. The soft stuff was loaded into the chamber, not from mag. I didn't pull the targets, they were soaked but @50 mostly My horiz. stringing.

 

[fiver]

that is odd.
the only way I could see it getting bigger is if it was fired or if just the primer were fired.

 

[popper]

Measured the second pulled boolit today, normal. Best guess, when jammed into the throat, it expanded into the case neck - bell wasn't completely removed with the FCD. The heel wasn't measured as it was pretty scuffed. Throat is badly scuffed too, have to get the chamber brush out. Looks like a very slight leading in the bore, in a couple spots. The cfeblk with the 170 should be 35-40k psi, 40sw loads about the same. Looks like the alloy is good for 30k min with no problem. melted all the ones I cast so far, add more Zn for the next try. The BLL ones I shot were barely on paper so IMHO, undersized a smidge, soft alloy, high pressure and the BLL gets blown off. Undersized PCd were not great but better.

 

[popper]

Measured noses of some of the loaded ones, slightly larger due to seating. Right where the dark band is on the 'stuck' one & at the end of the sizing marks but larger than sizer dia. Got to play with neck expander & sizers to see if I can get then seated without a bulge. Tight patch is after #9 and some dry ones. Loaded a bunch of H.J. over 5.7 of cfe pistol. Should give me better performance than 115gr. factory 9mm stuff, figure ~1400 fps.

 

[fiver]

the patch looks like just powder residue.

I'm pretty concerned about the diameter bumping your seeing.
it is telling me the alloy has no support internally and any type of compression is allowing the malleability to show through.
that's desirable on target but bothersome in the gun.

 

[popper]

Agree but same cast with BLL doesn't have this problem. Definitely seating tension problem.

 

[popper]

Shot the soft alloy in the 30/30 today, BLL & PCd. 185gr GC, 15gr 2400 @ 50 yds. Expanded the necks more to keep the nose from bulging. It was really hot today so not the greatest on the 2nd group with BLL but acceptable. Heard that somebody passed out there yesterday. Got off 75rnds of 40SW for practice with the soft, HiTeked. BO pistol with 6gr cfe pistol HJ 100gr. fired good but again, chamber is gunked up so I play pogo - empty cases! Remember to take chamber brush next time.

 

[fiver]

that's a lot better.
it's amazing how small little things make a huge difference like that.

 

[popper]

Yes, that extra 0.0005 does make a difference. Now to PC some of the PB and see how they work. Necks in the fired ones from the BO pistol were REALLY dirty. BCG was really dirty, hard to rotate the bolt & it has some lead specs in it. I hate taking it apart - 15 min. to get the cotter pin back in - hole alignment is bad..