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Are the USP compact 9mm and 40 frames the same? Conventional logic suggests they are identical but before I put a 40 cal upper on a 9mm frame and wanted to check with those in the know. What say the masses?
 

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Yes sir...and kudos for going the correct and safe route for a conversion...not a half-assed barrel...it should slide together and function fine (make sure you use the .40 recoil spring assembly!) Label them somehow if needed
 

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And you can also run a .357 sig through the .40 slide if desired...Not a fan here, but it is an option!
 

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Not entirely, or at least I wouldn't think so.

I can't check for myself since I don't have both a 9mm and .40 USPc, but I would think that the ejector on the .40 frame should be different than the one on the 9mm.

This may change the ejection pattern, as well as make the converted pistol less reliable in the converted caliber, than the original caliber that it came it.
 

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The frames are the same. The .45 frame is not.
 

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The frames are the same. The .45 frame is not.
This...

The 9mm the .40s&w and the .357 SIG are identical frames ...the .45ACP frame is larger...

Also magazines may be an issue since the feed lips are different diameters and gaps--they shouldn't be cross platformed
 

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1997 USP 9mm Full Size, too many upgrades to list.
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This...

The 9mm the .40s&w and the .357 SIG are identical frames ...the .45ACP frame is larger...

Also magazines may be an issue since the feed lips are different diameters and gaps--they shouldn't be cross platformed
I've read different. But I don't have any .40 cal mags to compare against my 9mm ones. Or is this just on the compact models?

-Sean


Typoed on my iPhone.
 

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Well that's interesting.

Does H&K uses the same ejector between the 9mm and .40 versions?

Every other model of pistol that I've seen that had a 9mm and .40 version, used a different ejector between the two calibers.
 

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9mm brass will physically fit inside a .40...if the feed lips were gapped for a .40 on 9mm magazines the spring wouldn't be able to maintain proper tension and result in misfeeds...likewise if you force .40s into a 9mm magazine it can lead to damage to the magazine...


The .40 and 357sig magazines are identical...which sometimes leads to confusion...
 

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Thanks for the details!


Typoed on my iPhone.
 

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The devil is in the details...I have an overabundance of 'semi-useless' information and judging by my post counter I have made use of a good bit of it
 

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9mm brass will physically fit inside a .40...if the feed lips were gapped for a .40 on 9mm magazines the spring wouldn't be able to maintain proper tension and result in misfeeds...
Exactly, the 9mm rounds sit much higher in the lips. It does mostly work, though the incidence of misfeeds is definitely higher. However, I'd argue it works for range use. I've gone through multiple mags before with no issue, so it isn't like it's choking every third shot.
 

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Exactly, the 9mm rounds sit much higher in the lips. It does mostly work, though the incidence of misfeeds is definitely higher. However, I'd argue it works for range use. I've gone through multiple mags before with no issue, so it isn't like it's choking every third shot.
With .40 mags available on here all the time, It just makes more sense to score 1 or 2 .40 mags for .40 use...but I'm also a 'right tool for the job' type of guy....
 

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Can someone with both a 9mm and .40/.357SIG caliber USPc check to see if they both use the same ejector?

I find it hard to believe that H&K would use the same one on both calibers. Since the ejector is molded into the frame, this would make the frames different if the ejectors are different.

Does H&K give the frames a part #? This may be another way to check.
 
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