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Discussion Starter #1
I have a HDPS UMP SBR pending transfer at my dealer now, as well as an AAC Ti-Rant .45 suppressor with 16x1RH for use on my Mark 23. The UMP has both .45 and .40 barrels. I'd like to have both threaded 16x1RH so I can use the same suppressor on them.

My questions are:
1) Are there any problems using the .45 can on a .40? If not, does it suppress well? If it's not effective at all I'll just save my money.
2) The barrel profile on the factory UMP barrels seems a bit awkward to thread because it seems they'll have to be reprofiled, but I assume this is possible. Anyone know who can do it? Would the entire barrel have to be refinished after the end is reprofiled or is the common practice to just touch up the threaded portion?
 

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1. There shouldnt be any probs with suppressing the .40 with a .45 can, especially with the Tirant. Will it be effective? Not sure.
2. I would use ADCO, IIRC it is 65 bucks, per barrel, with a week turnaround. Can you post a pic of your barrels? Im not sure what you mean by awkward.

***Get a fixed barrel spacer*****
 

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Discussion Starter #4
Both barrels are factory UMP barrels (just under 8" IIRC) with the flange.

Here's a pic of what mine looks like (except that it's factory and not a HDPS clone)
 

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1. There shouldnt be any probs with suppressing the .40 with a .45 can, especially with the Tirant. Will it be effective? Not sure.
2. I would use ADCO, IIRC it is 65 bucks, per barrel, with a week turnaround. Can you post a pic of your barrels? Im not sure what you mean by awkward.

***Get a fixed barrel spacer*****
Why do you suggest a fixed barrel spacer? I have guns without a recoil rod and I shoot them with the standard booster and everything seems fine.
 

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My questions are:
1) Are there any problems using the .45 can on a .40? If not, does it suppress well? If it's not effective at all I'll just save my money.
The .40 will suppress just fine. When I shoot the .40 (180 gr S/S)through my .45 can it is as quiet or may be more quiet than the .45.
 

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The .40 will suppress just fine. When I shoot the .40 (180 gr S/S)through my .45 can it is as quiet or may be more quiet than the .45.

And others have said it doesn't. All you can do is try. No points awarded for not trying... a 45 is hard enough to suppress with that dang ol' big hole in the end... 9mm cans do SO much better, but you do what you can with what you have. Some people have gotten VERY effective results with reloading magic to help the 45 suppress well. It can be a combination of things that will make it movie quiet... or you can settle for factory ammo and just be satisfied with what sounds like someone throwing a bag of concrete mix off the back of a pickup onto a plywood floor... not exactly gunshot loud, but you know somebody just lit something off.
 

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The volume of the can that is intended for a larger round but used on a smaller round helps. I was baffled(no pun intended) that a .223 shot through a .30 AAC can(friends) would be more quiet than my .223 can made for that particular caliber. Being that the exit hole and baffle holes are much larger and I assummed would let more gases escape, hence a louder report. It was explained quite simply, more volume in the .30 can. A lot bigger and heavier on the end of an AR but effective. But as shatteredmind stated some people have different results. I am not an expert and don't have the sound equipment to prove what I have stated but to my untrained ear that is what I and the others present perceived to be the case.
 

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I've shot .22 through my Tirant 45 and was pretty impressed. Would a real .22 can be better? Of course, but it works well enough to prevent me from spending $600+ on a dedicated .22 can and waiting 8 months. I'd bet a .40 will do well with the Tirant. I'm in the exact same boat as you. I think I'm going to get my USC barrel chopped and threaded at ADCO.

Back to my original question, I have a fixed barrel spacer for my Tirant. Would I need to use that with the Tirant if I put it on the UMP? I don't see why the recoil booster wouldn't work just fine?
 

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I have not seen metric threading listed on ADCO's site. You might have to get a new thread adapter in the standard thread pitch for your TiRant. They can be found at many class3 dealers or on AAC's website.
 

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Back to my original question, I have a fixed barrel spacer for my Tirant. Would I need to use that with the Tirant if I put it on the UMP? I don't see why the recoil booster wouldn't work just fine?
I don't own a UMP so I dont know if it has a fixed barrel? If the barrel is indeed fixed, then yes you would use the FBS. When I go from say My Glock 21 to the Kriss I have to use the FBS as the barrel is "fixed" in the Kriss
 

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I have not seen metric threading listed on ADCO's site. You might have to get a new thread adapter in the standard thread pitch for your TiRant. They can be found at many class3 dealers or on AAC's website.
I emailed them about this about a month ago. They said they will do metric. You have to specify it in the comments field.
 

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I don't own a UMP so I dont know if it has a fixed barrel? If the barrel is indeed fixed, then yes you would use the FBS. When I go from say My Glock 21 to the Kriss I have to use the FBS as the barrel is "fixed" in the Kriss
I understand when it is soposed to be used. I just don't understand why. I'm willing to be the operation on a UMP would be no different using a FBS or recoil booster.
 

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Skull, they say the booster puts undue pressure on the threads and that it could potentially ruin the threading on your barrel. Is this true? I don't know. I'm just telling you what I've heard. Would I risk an expensive barrel due to laziness? Absolutely not. So I'll stick with the fixed spacer. They make them for a reason.
 

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Skull, they say the booster puts undue pressure on the threads and that it could potentially ruin the threading on your barrel. Is this true? I don't know. I'm just telling you what I've heard. Would I risk an expensive barrel due to laziness? Absolutely not. So I'll stick with the fixed spacer. They make them for a reason.
Thanks. That makes sense.
 

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Why do you suggest a fixed barrel spacer? I have guns without a recoil rod and I shoot them with the standard booster and everything seems fine.
The booster is used to help mitigate the negative side effects of shooting a pistol with a barrel that moves like the recalcitrant Browning design. When the gasses leave the barrel they push on the baffles compressing the spring in the booster housing helping offset the weight of the can, almost making it weightless. Anytime you add any weight to your barrel it will change the harmonics. Think of it like a cars shocks, no shocks, the car will get beat up alot quicker. Some fundamental laws of physics going on here but unfortunately I cant comprehend any of the verbage. As far as a fixed barrel , its the exact opposite. The recoil and blast of gas of the host weapon will actuate the recoil booster, Nielsen devise , A.S.A.P. system or whatever you want to call it and make your can move. That back and forth movement can or may cause excellerated wear and and stress on your host weapon. It is highly recommended to use one but you dont have to.
 

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I don't own a UMP so I dont know if it has a fixed barrel? If the barrel is indeed fixed, then yes you would use the FBS. When I go from say My Glock 21 to the Kriss I have to use the FBS as the barrel is "fixed" in the Kriss
Most everything that's not a Browning-action pistol is fixed barrel. The UMP's is fixed to the upper with a barrel pin holding it in place.
 

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I recently had M16x1 left hand threads cut by YHM for their QD Wraith XL can for a post UMP, I bought a used HDPS Flanged carbine barrel from a board member here, Thanks! It works pretty well with a shot of White Lithium grease, allot quieter than I thought it would be, I really like the QD mount/Hider, can goes on and off quickly,here are some pic's, HTH


 
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