WTK 10mm problem/question

[Pinkerton]

Hi,

I have a 10mm load that I have used in my Delta with no pressure signs. It's a relitively lite load.

OK so here is the problem.

I have a Open bolt UZI. It fires Federal red box but blows the primers out. Wierd because I seem to remember that Federal is a lite load.

When I use my Reloads with new bress I get case seperations. Scary!!

The same batch of my loads rounds in my Delta are fine. No pressure signs/ no case seperations infact they seem lite.

The Federal I sent back to Federal and they said that they were fine and at about 1050 fps. (well within spec)

The guy that did the bolt and barrel says that they are both in spec and run fine in his with UMC 10mm.

I haven't been able to get UMC 10mm locally.

What would cause these issues?

Any help or guidence would be appreciated.

Thank You,

Pinkerton OUT!

[Skywalker]

Pinkerton,

the 10mm is relatively high-pressure cartridge.

My guessis that, if the open bolt UZI has a longer barrel than your Delta Elite, let's say a 9 or 10 inches barrel if compared to your Delta Elite 5" one, the rounds fired there might be developing far too high pressures, even if the same cartridge is safe in your Colt.

Try backing up your load and always verify with a chrono.

[shred]

It's not a .40 barreled UZI is it? Sounds like it could be a short chamber.

[joelaw99]

how deep is the firing pin dent in the primer, may be crushing the outside rim of primer in reducing its circumfrence and losing the tension that keeps it seated???

[Pinkerton]

Shred. No it's not a 40 Short and Weak barrel.

Joe Law 99 The primers are center hit and the ones that are still in the cases show serious over pressure signes.

Skywalker I think you're right I just figured that the open bolt would relieve that pressure. (on ther seperated cases the primer is still in the csae) That and I've run HOT 9mm through the 9mm set up with only a rate of fire increase. I'll give the crono a try.

[diehli]

My initial thought is that it's a timing issue. Could it be firing before it's in battery?

[Pinkerton]

300lbgorilla The issue is it's an Open bolt with Advanced Primer Ignition so the bolt is never truelly closed. I think a stronger spring might make the bolt faster on closing so it would be "more closed" Thanks for the idea.

The guy I bought this from told me that he has had none of these problems with the other kits he's sold to other guys.

[Harmon]

the gun is coming open too soon, there is still too much pressure on the brass.

its blowing federal primers because they are softer.

Try CCI large pistol, and put a stout recoil spring in it.

being straight blowback, plus a high pressure round, dont expect lengthy brass life

[Patrick Sweeney]

Harmongreer put his finger on it. The gun is opening while the chamber pressure is still great enough to expand and bust the cases. You need a heavier bolt (can't change that) or a stronger spring. the stronger spring might give you problems with bullet setback if you have any mis-match in neck expander diameter and case neck thickness. But that is easier to fix than case separations.

As for the Federal ammo blowing primers, softer primers would seem a likely culprit. Try a harder primer and see what happens.

A 10mm Uzi? You're making us jealous. If it is a select-fire, really jealous.

[Pinkerton]

It is a FA Uzi In .22, 9mm, 45 it is awesome. I'll try the stronger spring. Any ideas where to find one?

Thanks for the help!!!

Pinkerton OUT!