[AKM]

I posted this over in the reloading forum because we had been discussing high-pressure signs there previously, but I thought some here might not read over there.

I took my 460 Rowland to the range today and on the 3rd round I had a case head seperation. When I examined the other 2 cases, there was a ring which I hadn't previously noticed. This was with factory "self-defense" (light) loads. Obviously the slide is unlocking with high pressure still in the chamber. This is scary stuff and I need to know what's going on. This is with the boss filed down as discussed in the other post. Somebody help me out here.

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[Metal Smith]

Hi AKM,
I’m not familiar with the cartridge or set-up you are shooting, but in rifle cartridges when pressure peaks the first part of the case that grabs is front portion of the case because it’s the thinnest, the case gets thicker towards the case head, the front half sticks in the chamber and the head end blows back to the bolt face separating the case, you could have excessive head space, I’ll E-mail you for further help.

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Metal Smith

The only thing I know for sure is what I can measure!
NRA Life Member

 

[AKM]

My headspace is 0.019". I don't know if this is excessive, but it seems like alot for a cartridge that operates at 40kpsi.

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[This message has been edited by AKM (edited 10-07-2001).]

 

[Metal Smith]

Yes +.019 does sound like a lot, who makes the brass, is it formed from a parent case or is it afactory case?

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Metal Smith

The only thing I know for sure is what I can measure!
NRA Life Member

[This message has been edited by Metal Smith (edited 10-08-2001).]

 

[AKM]

It's factory brass specifically made for the 460 by Starline. The ammunition was factory loaded by Georgia Ammunition. The max case length for the 460 is 0.957. My brass is 0.955. I'm planning to call Clark Custom Guns (who made my barrel) today. I'm inclined to ask for a new barrel.

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[This message has been edited by AKM (edited 10-08-2001).]

 

[Ned Christiansen]

.019, probably plus whatever clearance is at the back of the hood-- in other words, total headspace is from the breechface, not just the depth of the chamber in the bbl. My only exp. with this cal. is in 625 revolvers, but I asked they guys I did them for not to shoot the Georgia Arms factory ammo (230 @1350). Just feels to dang hot to me, in the .44 Mag range, with thinner cylinder walls.

Good luck/be careful!

 

[AKM]

Actually the .019" I mentioned is the total headspace. I don't happen to know what the headspace spec is for 460 but I do know how to measure it. The loads I'm using are the "Self-Defense" loads which are "light" loads. Still substantially beyond 45ACP levels but well below the max for 460.

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[Bob Brown]

Hey guys, this is going to get interesting.
.019 is a bit much, but not overly excessive
IMHO. It sounds and looks to me like he either has a tight chamber or some serious bullet pull. I also wonder if his bullet is engraving the lands. At any rate,I think something is hanging on to the front part of that case and it separates just aft of the bullet base...at least that's what it appears to be from the photos. I've never dealt with this caliber before and I've also never seen a round separate like this. Like you guys,It seems to me to be a case manufacture problem.

 

[AKM]

Concerning the tight chamber theory, the rounds drop into the chamber easily and the front portion of the seperated case dropped out with just a tap.


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[Metal Smith]

Is this a factory manufactured round or wildcat?

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Metal Smith

The only thing I know for sure is what I can measure!
NRA Life Member

 

[AKM]

I guess you would call it a factory round. Starline makes the brass. Georgia Arms makes loaded ammo. Clark Custom Guns sells conversion kits for 1911s and is looking at offering a Glock kit.

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[Bob Brown]

I'm out of ideas. First, I'd shoot someone else's ammo and if it still separated,then call Clark's guys and talk about a new barrel with a shorter chamber to reduce that headspace. If it didn't separate, then look to your ammo builder.

 

[AKM]

I don't think anybody else makes loaded ammo. I can pull the bullets in the remaining rounds and reload them with a light load. If that looks OK then I could work up. But I'm still not happy with that headspace. I guess I'll have to call Clark about that.

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[AKM]

Well I talked to Clark Custom this morning and they said they had some kits with short leade that can cause excessive pressure. They said to send the barrel back and they will fix it. I will post the results here.


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[Bob Brown]

I look forward to seeing what happens after Clark "fixes" that "short leade" problem. That's what I meant when I mentioned your bullets engraving on the rifling. That's what happens with a short leade. I hope they give you a new barrel with a shorter chamber instead of just reaming to move the leade. .019 is a bit much.

 

[AKM]

Originally posted by Bob Brown:
I hope they give you a new barrel with a shorter chamber instead of just reaming to move the leade. .019 is a bit much.

I hope so too. I included a letter with the barrel expressing my concern about that.

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[Metal Smith]

Hi AKM, yes, increasing the lead or free bore and angle of the lead into the rifling will reduce pressure, Weatherby cartridges have plenty of free bore to reduce pressure.
I never mentioned the lead because it seems unlikly that you could generate enough pressure by having just a short lead with a light load to blow a case head. I think Bob is right. Next thought; if this cartridge is that border line on pressure to blow case heads, I'd tell Clark your not satisified and get your money back, lifes to short as it is to mess with a design like this!

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Metal Smith

The only thing I know for sure is what I can measure!
NRA Life Member

 

[AKM]

OK, got my new barrel from Clark's Custom. The headspace is around .003" and it has a nice long leade. I'm taking it to the range tomorrow AM. If you don't hear from me, check the hospitals.

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[AKM]

Back from the range. The pistol is much better behaved with the new barrel. The blast and recoil are noticeably less and there is no sign of case stretching. Still have the flattened primers and breach-marks on the brass, but this is a high-pressure cartridge.

Also, this barrel seems more accurate than the other one. I shot a group around 4" at 50ft offhand. The indoor range doesn't have any accomodation for shooting from a rest, so I'll have to wait to do real accuracy evaluation.

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[This message has been edited by AKM (edited 10-21-2001).]