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Discussion Starter · #1 ·
I started to work on the sti mags for a 10mm conversion. Noticing they don't have the same angulation to feed as the .40 usp mags.
Then I thought I would try .40 upper one.45 lower. It shot fine except a few rounds nosed up and blocked slide from closing. But it seems like a better way to get to the finish line. The lower did protrude a few mm's beyond the .40 slide. But not enough to be an issue for me.
I am either going to attempt to bend the USP .45 mag feed lips in to spec to correct the rounds excessive tipping up; Or I have a spare usp compact .40 mag at a friends shop that I may try to remove the steel insert from the mag and sleeve the .45 with .40 feed lips. That probably is not practical as I bet that would cause the follower to catch on the sleeved insert.
Anyone have ideas on getting a .45 mag to feed 10mm better?
Perhaps the sti mags having a lower bullet angle is not an issue. But I am just sorting thru the issues before I start hacking on mags.
 

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Discussion Starter · #2 ·
I can tell be the ubundance of responses that you guys were glued to your seats for an update...
I Shot the 10mm USP for a few shots today and it seems to be functioning fine
To recap, I put the USP .40 slide on the .45 tactical frame. I used the factory .45 mags
I test fired with the factory recoil spring today and it was for sure undersprung.

I have not bent the feed lips on the .45 mag yet and I had one round attempt to go over the barrel. They do seem to be angled a bit high as the fat feed lips let the rounds rise up a bit
I plan to alter the .45 feed lips and reshoot tomorrow with the 18lb recoil spring.

I ended up reaming the efk barrel myself.
Not a big deal
Once I get the feeding dialed in then I will
Plan on opening up the ejection port to eject live rounds.
The slide does hold open on the last round as configured now.
If this thing shoots as a factory 10mm does then I will remark slide as 10mm tactical and refinish. Considering an rmr as that extra weight on the slide may help tame the beast
Stay tuned for more
 

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Discussion Starter · #4 ·
3rd range trip.
The gun shot the 10mm well with the 18lb recoil spring. I bent the .45 feed ramps to 9.4 mm or so...close to the .40 size
That seemed to help. But then I had a few rounds get hung on the case lip on the upper feed ramp area.
I got home and compared the stock barrel and the efk barrel up feed ramp areas.
The stock barrel is much smoother, whereas the efk has a distinct change in the slope. That leaves a small lipped area that is the culprit.
Picture shows the differences
Next step is to see if I should adjust this myself or let someone with better tools tackle the job.
Then retest and open up ejection port
The 10mm USP is a handful

I did have once that the hammer did not stay back?
 

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Discussion Starter · #6 ·
I went ahead and opened up ejection port and smoothed the feed ramp.
I compared the feed ramp to my .45 and .40 usp
The long 10mm was binding nose up in the barrel.
So it cycles 100% by hand now. (Can rack the slide and it feeds and ejects as a factory gun should.)Slide also has been staying open on last round.
Too late to go back to shooting range today
So that just leaves test firing.
Pic shows ejection port opened
 

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Watching with interest. I just sold my glock 20 last month because after everything i put into it and the fact that i love the 10mm i could not grow to love or even like the glock. Was thinking about going with a witness in 10mm or dropping the cash and getting a sig.

Sent from my LGUS990 using Tapatalk
 

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Discussion Starter · #8 ·
I had a Eaa stock 3 10mm. Look at that one. Sold it and got a 9mm. Thinking I could then get the 10mm conversion. But they are out of Conversion kits
It really isn't that hard to convert a usp.
I wanted a factory looking and functioning gun. If I can't get it to run 100% reliable then I will try the sig next.
I had a few smith 1076's two. Solid guns.
Building a mp5 10mm now also.
I have the reamer now too....
 

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I went ahead and opened up ejection port and smoothed the feed ramp.
I compared the feed ramp to my .45 and .40 usp
The long 10mm was binding nose up in the barrel.
So it cycles 100% by hand now. (Can rack the slide and it feeds and ejects as a factory gun should.)Slide also has been staying open on last round.
Too late to go back to shooting range today
So that just leaves test firing.
Pic shows ejection port opened
Soooooo? How'd it work out?!
 

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Discussion Starter · #10 ·
Oh,
So I took it hunting and got to fire off 3-4 rapid fire shots in the heat of the moment...that's the only chance I have had to shoot it..

I am loading up some 10mm now, I will test it out more in the next few weeks when I get a Chrono up and running.


In that very limited test it functioned perfect. Honestly I forgot it was a home brew gun....

I have no reason to believe it will not function 100%, unless the feeding is an issue.
 

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That's cool that you have a practical use for it. I feel sort of silly with mine since I'm just shooting hot boutique 10mm at paper or whatever.
 

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Oh, man...am I going to have to buy a couple of USPs now to Frankengun together? I've wanted a 10mm USP for a looooong time.
 
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