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Discussion Starter #1
Hey guys, a buddy at work today asked me if the USC/UMP chamber is reinforced and capable of effectively cycling and shooting the 45 supers or the 460 Rowland. Has anyone ever tried it? I ask because the 460 could be a great round considering it can hit 1,500 FPS with a 185 grain bullet out of a 1911, so probably similar in an SBR UMP.

Any info is appreciated. For reference:
.460 Rowland - Wikipedia, the free encyclopedia
 

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Interesting, I'd not thought about this... I don't know, but now I'm curious...
 

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Discussion Starter #3
I think the biggest problem is, if we try it and it goes wrong, you've probably blown your gun up or severely damaged it.
 

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Yes, it's reinforced.
The PLASTIC that it's made of is reinforced with fibers and thin metal sections where it is needed to withstand it's
NORMAL STRESS from a NORMAL LOAD.
If they had to reinforce it for the .45 I would not bet that it will hold up under the stress that .45 super or .460 is
going to subject it to.
 

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Discussion Starter #5
Yes, it's reinforced.
The PLASTIC that it's made of is reinforced with fibers and thin metal sections where it is needed to withstand it's
NORMAL STRESS from a NORMAL LOAD.
If they had to reinforce it for the .45 I would not bet that it will hold up under the stress that .45 super or .460 is
going to subject it to.
That was my assumption as well, being a polymer gun. So it may not even be safe to run some slightly hotter hands loads then.
 

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Sounds like you might be just as happy with a mp5 in 10mm.

Whole lot of power for a 'pistol' caliber subgun.

And if you've got the cash you can sear it and really go through the cash. =)
 

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Sounds like you might be just as happy with a mp5 in 10mm.

Whole lot of power for a 'pistol' caliber subgun.

And if you've got the cash you can sear it and really go through the cash. =)
++1. I have an MP5/10 SBR and it is a powerful and fun pistol caliber gun. I bought a CA-89/10 first and fell in love with the power of that caliber in that gun. You can probably get into a CA-89/10 for $1500-$2000
 

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I would trust it with a slightly hotter load.
The .460 R isn't just a slightly hotter load. Look at some of the pistols that came out for it and what they had
to do to modify a 1911 to work with it. They added a compensator and a stiffer recoil spring and it already had
a fairly hefty metal slide and frame that the 1911 came with already.
 

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Discussion Starter #9
I would trust it with a slightly hotter load.
The .460 R isn't just a slightly hotter load. Look at some of the pistols that came out for it and what they had
to do to modify a 1911 to work with it. They added a compensator and a stiffer recoil spring and it already had
a fairly hefty metal slide and frame that the 1911 came with already.
Yea pretty substantial upgrades. It's not that I don't think the 45 ACP will be enough, Lord willing I will never use mine on the two way range, but I wanted to understand all of my options.
 

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Well your options are .45, .40 and 9mm ;)
I have a .40 kit for mine and will probably get a 9mm setup for it
when I have the cash and magazines are a little easier to get hold of.
 

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.45 super will probably be okay, its a little hotter than your standard +P 185 grain round, however it's going to cycle the bolt faster. Since there isn't really any delay in the USC bolt other than weight, it might end up hitting the buffer a little harder, although the buffer does provide a good impact dissipation point.

Considering the "thickness" of barrels that .45 super is normally shot out of, the USC45's BARREL is most definitely capable of containing the higher pressure with no ill effects, however with any hotter loads, you're basically just wearing the parts out quicker by shooting the hotter load in it.


I put some "above" max load reloads into my Mark23 (max grains of Unique was 6.9 grains and I put 7.5 into some really hot loads). Gun had noticeably more recoil but handled it just fine. Obviously if you put that kind of ammo through it on a more regular diet, it WILL shorten the service life of the gun.
 

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Bumping up this older thread...

I have a USC/UMP conversion that was done by Tactical Excellence as an SBR. The original 16" HK barrel has just been sitting in the bottom of my safe feeling lonely. Today, a buddy and I used a Manson Reamer to lengthen the chamber of the original barrel to 460 Rowland specifications. The chamber of the barrel is certainly capable of handling the pressure, and the case head is fully supported. Since the carbine uses a heavy bolt, has a stout recoil spring, and a buffer to take the bolt strike -- I'm thinking about "pulling the trigger" on a couple of 460 Rowland (Underwood Ammunition) loads to see what happens!!!

The Germans are notorius for over-engineering their firearms -- so, I think I might give it a try. I shoot 45 Supers in an unmodified Springfield XDs -- and they work fine...

What do you guys think??
 

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I'm going to err on the side of caution here and *not* rec that you do the .460. I have several Springers that I changed over to .460 Rowland and it's a lot more than the .45 Super. It's the pressure that you need to worry about:

.45 ACP 21,000 PSI
.45 ACP +P 23,000 PSI
.45 Super 28,000 PSI
.460 Rowland 40,000 PSI

While the Germans do tend to overbuild things, nearly doubling the PSI from what the gun was built for is not going to turn out well over the long haul. Also consider that this is a straight blow-back design in the USC and that is going to put a LOT of crud out of the ejection port, especially at that pressure. The 1911 design *requires* a stiffer spring and a comp just to manage the increased velocity of the slide from all that pressure.
 
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