What in the name of god happened to me?

B

briandg

New member
A smith and Wesson MP body guard, .380 semi auto, retarded blow-back. if that is important.

I took a batch of current loads out, and along with all of the inherent problems I have found this thing to have, the accuracy went off the rails.

I fired 24 rounds at 4 targets. I fired the first at about 25-30 feet and got a 3 inch group, as expected. the last one was a flier that missed the paper. This was single handed, off hand. The next three papers I fired two handed, with a little more care to my aim, and each paper got progressively worse to the point that I missed the paper several times, when every round should have been dead center onto the 3 inch target spot. I'm used to being hit in the face with powder scatter some times, i'm used to being hit in the face with brass, but not this!

I examined the paper. as the shooting progressed, the punched holes got dirtier, and from the very beginning I found fine particles on the paper surrounding the target. from 30 feet? The particles obviously worsened as the shooting progressed. I used a 50 power glass to examine everything, brass, paper, bore, breach block, everything I could examine with it and then resorted to 2.5 reading glasses. Other than maybe a little more brass marking on the steel, possibly a dirtier bore, nothing at all. Brass seemed to be perfectly normal. The particles were either dust shaped or slightly needle shaped, and it did not appear that I could smear them.

I was shooting a tested round of accurate 5 with a 100 grain plated bullet. its a start load. the bullet was a different maker and shape, but still a starting load from this company that didn't specify a brand of bullet. Bullet was a flat based round nose with a flattened meplat.

What have I done? how in heck am I going to know if I went over the pressure level? what else could have gone wrong? I used the 100 grain slow powder to stop failure to eject problems, and the problem returned.

bullets are flat based, but hollow based were available. could that be it? is it the powder/bullet combo, but why did it fail this time?

I wish I had some previously fired brass to compare, but no luck there.
 
most of the evidence is microscopic. You'll just have to go with what I put in the post. there isn't anything unusual, but the scorch marks were a little less pronounced at the mouth of the shell. The primers were CCI and all were light strikes. brass should have been once fired. a run down the barrels outside with a caliper showed no variation, and there were no unusual spots in the bore.

Except for losing my barrel, I didn't find anything more that was unusual. If i hadn't left the barrel on the cleaning rod, I wouldn't have lost it.
 
Sure sounds like the lead was coming out of the bullet. I did not know that could happen with plated bullets out of pistols. Your pressures must have been too high.

Besides cutting the charge, run some JB bore cleaner down the barrel and clean it out. Get that barrel mechanically clean with an abrasive, if there is impacted crud, a chemical cleaning won't remove it.
 
Accurate 5 sounds right.As I recall its what I chose for 9x18 Mak.
I might be wrong,but the first thing I would look at is bullet dia.
While a bullet bore dia,or .001 or so over likely works great,a bullet .001 undersize likely will perform poorly.This is in large part to the effects of hot,high pressure gas leakage around the bullet.
I have not used many copper plated bullets.Do the come lubed,or do they skip that?If they are unlubed,you may have something to try,if they have a lube groove.Or try a dry lube .

I wonder if moly or Alox tumbling a bullet like that would help the softer bullets scoot up feed ramps,too.
 
1. Try measuring the remaining bullets to see if the diameters are consistent.

2. Make sure there is no lead in the bore. If there is, clean it out thoroughly.

3. Use a decoppering agent, such as Sweets 7.62, to clean the bore in case it's coppered up. Read and follow the instructions carefully.

4. Next time you test the pistol, take 10 rounds of factory ammo to test first, just to see if the gun is shooting accurate with it. Shoot off sandbags at a known distance. If you have some other plated bullets left over from past successful loadings, re-test them to see if they still shoot OK. If they do shoot OK, then the issue is most likely the new bullets you are using.

That's my 2-cents worth.

Gene Pool
 
I scrubbed out the bore, and only got soot.

That advice was along with my own thoughts. Try the previous loads, run some factory, and that can establish that the flaw is in the new stuff.

Definitely need to check the diameter.

Fire some test rounds into the rain barrel.

Scrape up some of the residue and check with microscope.

The thing that keeps coming to me is the information that I have heard about hard cast rounds being used in rounds too weak to seal the bore.

Ill tell you, I'm getting really tired of this project. It's depressing to watch a decent group just keep expanding.
 
The thing that keeps coming to me is the information that I have heard about hard cast rounds being used in rounds too weak to seal the bore.
Click to expand...

I don't use "hard cast" in anything, handgun wise. I just don't believe in it. BUT, when you have to shoot commercial bullets, that is all you can get.

My bullets for 380, 9mm, 40, & 45 ACP are all BHN 8.

My bullets for 44 Mag & the 500 S&W are cast at BHN 10-12.

Either your bullets are too small, or as you suspect, they are too hard.
 
Oh, I found the barrel. I wiped the bore to drag off whatever I could find and pulled the patch after the first pass. I examined the patch, and left the barrel on the end of my black cleaning rod. Half an hour that I'll never get back.
 
Stupid questions:
Did you look in the clean bore for evidence of leading or copper?
Did you run any ammonia-cleaner through the bore?
Did you slug the barrel and find what the real groove diameter is?
Are your plated bullets 0.001" larger than actual groove diameter? To me, plated are the same as lead and work best when slightly over-size (though, again, for me, they still don't work too well).
Retarded blowback? Do you mean straight blow-back (like most .380s) or short-recoil (like a 1911)? The only "retarded" systems I am aware of are roller-delayed and case-delayed (where the chamber has grooves that the case flows into to retard extraction, but cases aren't usually reloadable).

FYI: If you order 2000 or more, you can get Precision Delta JRNFP bullets for $87/1000. For me, jacketed is always better than plated.
 
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