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Military Firearm Restoration Corner

Homebuilt 10Mm


Sailormilan2

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Since I live on the left Coast in Sunny CA, where 10mms are hard to find, I decided to put one together. I located a ParaOrdnance slide with a breechface cut for 40cal/10mm rim, and a rather inexpensive barrel, and put one together using my RIA Tactical 45acp frame.
Once my taper crimp die got here, I loaded up some ammo using two different bullets and powders. Loads were a powder coated 175 gr SWC over 6.4 gr of Unique, and powder coated 180 TC bullet loaded over 12.7 gr WC820(basically AA#9). Barrel must have a tight chamber, because loaded uncrimped rounds that would drop into my Midway case gauge would not chamber more than 1/2 way.
I used a flat based firing pin stop, 23# mainspring, and 20# recoil spring. I am probably going to have to go up to 23# recoil spring, as empties were landing 20 feet away.
I was very surprised by the groups I got. I am out of practise, and yet they were decent groups. Better than what I expected for a $72 barrel.
Group 1, using midrange Unique load, shot at 10 yds, two handed hold.
10mm10yds1_zpsz1egkume.jpg

Second group, using the WC820 load was fired at the same target as I wanted to see how much of a POI change there was.
10mm10yds2_zpshnemezuy.jpg

Final group was 4 rounds from each load, total of 8 shots, fired from about 18 yds, supported.
10mm18yds_zpsqmojjhhz.jpg

The primers look like they might be flowing a bit, and the loads aren't that hot. I used an old Colt 9mm firing pin, and it might be undersized. Since I am using a ParaOrdnance slide, I think I will try to find a PO 9mm firing pin, and see if that changes any thing.
10mmBrass_zpso69e5muw.jpg

Today's shooting was merely to test everything to see how it functions, especially the barrel. If it wasn't accurate, then I was going to have to find another one. But it seems fine.
Just for giggles, I dropped my 9mm barrel into the slide and fired some shots at 10 yds. Using 124 gr ball, and about 5.5 gr Unique, POI went up about 4". I think I was save that barrel for the dedicated 9mm/38 Super slide that I have.
Right now, I can use my Rock Tactical for the 45 acp it came as, and then switch slides and barrels and go to 9mm, 38 Super, and 10mm. I'm debating on going to 40 S&W.
But, now to order a heavier spring.

 


Para10_zpsnv6epl2s.jpg

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Beyond way to cool!! If the firing pin doesn't fix the expended primers you might want to double check the headspace. Have you tried different brand of primers? I had a Walther P-38 that did nearly the same with fired primers even with factory ammo. Never burst one so I learned to live with it.

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