align=middle
Semi Automatic Pistol

A 10mm USP Conversion? | Lifesizepotato Flexes

Self-proclaimed HK USP fanboy LifeSizePotato takes us on a video tour of his 10mm USP conversion. LifeSizePotato has an epic YouTube channel with some rather rare handguns that make me drool every time he releases a new video. I would sell a kidney to get a chance to go through his collection and fondle all the ultra cool pistols.

This video, he shows us his latest project gun, a Heckler Koch USP .40 S&W that he has converted to fire 10mm. Apparently, this is a conversion that has been floating around the gun world for some time that seems to have eluded me. As a USP fanboy, I am nothing short of disappointed in myself for overlooking this mod.

Hell, I even had a police trade-in USP .40 a while back that I picked up for a song and sold promptly because I came to my senses and decided adding another caliber to my collection was stupid.

LifeSizePotato says he used a modified STI magazine, an 18-pound recoil spring, and an EFK Fire Dragon barrel reamed out to 10mm by a gunsmith to create the German 10mm powerhouse. Since HK never produced a USP in this caliber it is super cool to see a fan of the platform build something that probably should have been built to begin with.

If you haven’t checked out his YouTube channel, it has some outstanding content. You should probably block off an hour or two to spend drooling over his collection.

Patrick Roberts

Since founding Firearm Rack in 2014 which evolved into Primer Peak in 2020, Patrick has been published by RECOIL, Ammoland, Gun Digest, The Firearm Blog, The Truth About Guns, Breach Bang Clear, Brownells, The Shooter's Log, and All Outdoor. When he isn't writing you can find him instructing handgun and AR-15 courses, training his dog Bear, or spending time with his son Liam. See what he is up to on his YouTube Channel, on Facebook, or on Instagram at @thepatrickroberts.

Share
Published by
Patrick Roberts

Recent Posts

Federal FliteControl Vs. Hornady Critical Defense in the Beretta A300UP [2025]

Here at PrimerPeak, we're fans of the Beretta A300 Ultima Patrol. Dan reviewed his back…

6 days ago

Purse Carry: Last Resort or Valid Option?

It’s often touted that purse carry is a dangerous option that should never be considered.…

2 weeks ago

I Walked Out of Class, Here’s Why

I attended my first formal shooting lesson as an adult in 2012. Since then I've…

3 weeks ago

SIG Sauer P320 Banned from use in IDPA [2025]

The saga surrounding the SIG Sauer P320 continues to evolve. This morning we woke up…

4 weeks ago

Living Legends | Interview with Simon Golob

We spoke with martial arts champion and instructor Cecil Burch during our last Living Legends…

4 weeks ago

Top 5 SIG Sauer P320 Alternatives [2025]

If you've been anywhere in the gun space over the past few weeks then you're…

4 weeks ago