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Discussion Starter · #1 ·
Hi everyone, I recently finished putting together a UMP clone in .45 using the Omega Gideon Shadow receiver. I took it out today for some first shots, put a mag in, charged it and got a click and no bang. When I went to cycle the gun, it was completely locked up, and had to be mortared to clear it. I attempted again, this time the round I chambered fired, ejected, but the next round loaded in failed to fire and seized the gun in the same fashion. When I got home, I took out the bolt and recoil spring, and put a round into the bolt and seated it into the barrel by hand. This also caused the gun to lock up and it needed to be mortared again. I am not using any special ammo, just Remington UMC .45 FMJ. Has anyone experienced this, or knows what would cause this issue? I know there is some compatibility issues regarding certain bolts and barrels, I am using the following:

BOLT: https://www.hkparts.net/shop/pc/viewPrd.asp?idproduct=18751
BARREL: https://www.hkparts.net/shop/pc/viewPrd.asp?idproduct=18678

Would these be the culprits causing issues?

Thank you all so much
 

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are you able to inspect the chamber on the barrel? it seems like it's getting stuck there so i'd suspect either something gunked up in there or else the barrel itself or ammo out of spec
 

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Discussion Starter · #3 ·
The only other ammo I've got laying around is some steel TulAmmo, which also gets stuck. It is a brand new barrel, I would be surprised if it was out of spec. I guess I can take a brush and some Hoppes to it just in case there is some residue left in it.
 

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Yah kinda lame if that's what it is, I've been looking at building one myself and was looking at those barrels as well. Not quite the same but I had an AR barrel that would do the same thing, it was a cheapie so I ended up just polishing the chamber and worked fine after that until I eventually used some IMI rounds that had some sort of sealant around the bullets... had one of those get stuck bad enough that when I mortared it the bullet stayed in the throat and the case and powder came out.
 

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I would replace your barrel with an HDPS or HK part. The HKparts website doesn't list a source for the barrel. My guess is that barrel is completely out of spec.
 

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Do you have a spent casing that you can put into the chamber to see if you get the same result? The other issue I can see is the bullet itself is starting to engage into the rifling and therefore will not allow the bolt to fully seat the round. If you are using factory ammo, then its possible the barrel chamber is at fault.

If you have one of those rounds that you 'mortared' out of the chamber, you could inspect the bullet to see if there is evidence of the rifling engagement on the bullet ogive. I've been reloading .45 ACP since the late 70s, but recently had the same issue when I loaded up 500 rnds for use in my USP-T. Went to the range and first round fired perfectly, the second round always failed and I noticed the slide was not fully closed. Popped out the round by carefully tapping the slide on a piece of 2x4 on the bench; I noted slight markings where the polygonal bore started to engage the bullet. Obviously killed the day of shooting .45 thru my USP-T for sure. Back home I inspected the OAL of the cartridge and it was spot on for a .45ACP 230 gr FMJ round. Then compared the batch of FMJ bullets I was using from other 230gr FMJ and noted that these bullets have a slightly longer ogive (start of bullet taper) that essentially caused the bullet to engage into the polygonal bore. The ogive of a bullet should be seated slightly back of the free throat 'jump' area of the chamber. All was not lost with the 500 rounds of .45 ACP and I just adjusted my Dillion 550B to seat the bullets a bit deeper into the case and ran them all through the press bullet seating stage; problem solved and lesson learned.
 

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Discussion Starter · #7 ·
Unfortunately I was only able to get that one round to fire, the case is long gone. Any other rounds I chamber won't fire and require mortaring to remove them from the chamber. The bullets themselves don't exhibit any deformations like you are describing, though the cases themselves I've noticed are scuffed up moreso that I would expect from just being chambered. I'm using factory ammo, so I am leaning more towards faulty barrel. I'm going to try my hand at polishing the chamber, just to see if that will have any effect. If not, I'll be shopping for a new barrel.
 
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