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Discussion Starter · #1 ·
Had to try it; following Lifesizepotato's lead on this one
Found a used USP .40, contacted EFK and got one of the last USP .40 threaded barrels in stock (she said they were not making any at the moment)
Have a 18# recoil spring in hand
Bought two STI 140mm .40 mags
Jet funnel arrived


I plan to test the .40 barrel once I get the gun in my hands...shoot it a 20-30 rounds or so to test reliability before I ream the barrel.

Then send the barrel to ream to 10mm; (open to suggestions on who to do that service?)

If this all works as I hope; I plan to open the ejection port up (Its been done before, but I can't get any decent pics to show what they did)

If it runs flawlessly, I will go ahead and remark as 10MM tactical and maybe mill for RMR (I can't recall who the go-to was on the USP, L&M or Ashbury??)



I also have a MP5 10mm project underway; should make for a nice combo
 

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Discussion Starter · #3 ·
I don't have the gun in my hands yet; it was delayed in getting shipped out....
The guy that reamed yours in no longer taking new business....
 

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I don't have the gun in my hands yet; it was delayed in getting shipped out....
The guy that reamed yours in no longer taking new business....
Oh, bummer! Well, barrel reaming is a pretty easy and common thing, the only trick is finding someone with a 10mm reamer. You might check around with local smiths.
 

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Discussion Starter · #6 · (Edited)
So, I just ordered the parts (reamer, handle and go-gauge) from Dave Manson Precision Reamers; He talked me thru the process. Seems pretty straight forward.

Now I need to figure out how to change the .40 S&W (Short and Weak) markings to .40 L&H (long and hot)... :)
 

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I'm looking at the same project. Joined today for the info, and my new appreciation for HK. There's a member threatening to do a group guy on barrels for these conversions in another thread, FYI, though he hasn't updated which the pricing for the past two weeks. Hope he comes through.
 

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im tackling this project as well. Any update from you scubadds? Here is a picture of a usp 40 w/ jet funnel and STI 140mm mags:
Firearm Gun Trigger Airsoft gun Gun accessory
 

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Discussion Starter · #10 ·
Sorry to not have followed up

I ditched that method...The STI mags don't hold the slide open on the last round....

I reamed the .40 barrel myself, opened the ejection port so it ejects a live round. Put the 18# spring in...

Then put the slide on a .45 tactical lower and used the .45 magazine with a slight bend in the feed lips

I have put about 15 rounds thru it (need to chrono my 10mm rounds before I reload more)

Seems to function 100% as it should...
The ,45 frame is about 3mm longer than the .40 slide...
I plan to retest, and purchase a .45 frame trim it to fit; and remill the slide for 10mm tactical markings...

I will follow up with a real post with the results.... Firearm Gun Trigger Gun accessory Air gun
 

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That sure is a good looking pistol. Wouldn't it be nice if it was yours?
BUSTED!

hahah I was hoping you wouldn't notice me stealing pictures of your gun. Don't your STI mags lock back on the last round? I would think missing that feature would be very problematic in competition
 

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BUSTED!

hahah I was hoping you wouldn't notice me stealing pictures of your gun. Don't your STI mags lock back on the last round? I would think missing that feature would be very problematic in competition
They are designed to lock open with the factory followers but In the 1911/2011 competition space, the locking tab on the follower takes up space that can be used for another round and often causes the slide to lock open prematurely. Most competitors disable it as it's not really needed. In the guns that use these mags, you never shoot to empty unless you really screwed up.

Sent from my Nexus 6P using Tapatalk
 

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Sorry to not have followed up

I ditched that method...The STI mags don't hold the slide open on the last round....

I reamed the .40 barrel myself, opened the ejection port so it ejects a live round. Put the 18# spring in...

Then put the slide on a .45 tactical lower and used the .45 magazine with a slight bend in the feed lips

I have put about 15 rounds thru it (need to chrono my 10mm rounds before I reload more)

Seems to function 100% as it should...
The ,45 frame is about 3mm longer than the .40 slide...
I plan to retest, and purchase a .45 frame trim it to fit; and remill the slide for 10mm tactical markings...

I will follow up with a real post with the results.... View attachment 127738
wait, WHAT? You can slap a complete 40sw slide on a 45 frame and it functions?? I thought the frames were way different and none of the controls lined up. Can you do the same thing with a complete 9mm slide on a 45 frame? Maybe thats what i was thinking of
 

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They are designed to lock open with the factory followers but In the 1911/2011 competition space, the locking tab on the follower takes up space that can be used for another round and often causes the slide to lock open prematurely. Most competitors disable it as it's not really needed. In the guns that use these mags, you never shoot to empty unless you really screwed up.

Sent from my Nexus 6P using Tapatalk
that makes sense, shows how much i know about competitive shooting!
 

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wait, WHAT? You can slap a complete 40sw slide on a 45 frame and it functions?? I thought the frames were way different and none of the controls lined up. Can you do the same thing with a complete 9mm slide on a 45 frame? Maybe thats what i was thinking of
The 45 frame is very different than the 40/9. I'm surprised it works at all.

Sent from my Nexus 6P using Tapatalk
 

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Discussion Starter · #17 ·
Yep....I put a .40 slide on a .45 frame and so far it works fine....

I have yet to really put it throw a high round test;
 

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Sorry to not have followed up

I ditched that method...The STI mags don't hold the slide open on the last round....

I reamed the .40 barrel myself, opened the ejection port so it ejects a live round. Put the 18# spring in...

Then put the slide on a .45 tactical lower and used the .45 magazine with a slight bend in the feed lips

I have put about 15 rounds thru it (need to chrono my 10mm rounds before I reload more)

Seems to function 100% as it should...
The ,45 frame is about 3mm longer than the .40 slide...
I plan to retest, and purchase a .45 frame trim it to fit; and remill the slide for 10mm tactical markings...

I will follow up with a real post with the results.... View attachment 127738
This is an incredible project--- please keep us updated in the process!!! :eek:

Tony
 

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Discussion Starter · #20 ·
Thanks. I found s .45 lower inbound next week... that way I will not need to use my .45 tactical lower.
I plan to go ahead and trim the frame back to fit.


Sent from my iPhone using Tapatalk
 
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