I?ve only had one MIM part fail. That was an ambidextrous safety on a Rock Island 1911 that apparently was put together using a reverse dovetail where the two halves joined. The harder I tried to get it apart, the tighter it became. I finally broke it to get it apart.
But, that was not the fault of the MIM process or the part.

For 10mm, I?m currently running a 25# MS, with a 20# Recoil Spring in standard Government model(5? slide). It?s not really recommended to go over a 20# recoil spring, since going higher can cause frame battering and damage when returning into battery. I?m giving serious consideration to upping the MS to 28#, since my guns are still throwing the empties over 10? feet.

I had a 6? 10mm 1911 upper laying around, and talked my youngest son into putting it on his Springfield Military 1911 in 45 acp. I managed to find an ejector that would work with both slides. 1911s use one size ejector for the 45 acp, and a slightly different sized ejector for all other calibers. This means that slides cannot be interchanged, unless one, or the other, is modified. Fortunately, I had one that works in both.
Then I reshaped the tang so that it will take a beavertail grip safety. It had a Rock Island ambidextrous safety, since he?s left handed. Then upped the Main/Hammer Spring to 25#. I may end up increasing it to 28#. I had to replace the hammer, since the one on the gun kept getting jammed in the slide. Then I refinished the frame, and original slide In black parkerizing.
Setup retains the ability to go between a 5? slide 45 acp, and a 6? slide in 10mm. My son is happy.

https://imgur.com/1e3oXqU

Quote from: Graybeard on January 05 2023 01:11:09 PM MST

Quote from: Sailormilan2 on January 05 2023 12:32:47 PM MST
I recently posted on another gun related forum about the use of Blue Dot and AA#9, and that both were often recommended for use in the 10mm. Another member, possibly a professional gunsmith, posted that neither powder had the proper burn rate for the 10mm. Especially the AA#9.

Sounds like he didn't really know what he was talking about then. Blue Dot can be used for some very accurate loads in 10mm, although not the fastest. AA#9 works just fine in 10mm.

Agreed. I sent the OP, who was looking for advice on reloading the 10mm, a private message to come to this Group for information on the 10mm. I have no idea if he has done so.

I recently posted on another gun related forum about the use of Blue Dot and AA#9, and that both were often recommended for use in the 10mm. Another member, possibly a professional gunsmith, posted that neither powder had the proper burn rate for the 10mm. Especially the AA#9.

Quote from: gnappi on September 16 2022 10:34:03 PM MDT
I have a Bul SS commander in .357 Sig and an all steel RIA commander in .40. I'm thinking of a replacement 10mm barrel for the RIA. Anyone have a steel 10mm commander sized pistol to comment on?

I have put together a couple of Commander sized 1911s and have put a 10mm barrel in them. I used the stainless steel barrels from Numrich. They are "drop in", but are a very good fit in my slides.  They will need to be finish reamed.  I have used 5 of them.  3 in Full size, and 2 in Commander. You should install a Flat Bottom Firing Pin Stop in your slide, and up the Main(Hammer) spring to 25/26#.
I put together a CCO type 1911, using a Detonics style frame and a Commander style slide, and played with a 10mm barrel in it. It worked fine. But I felt like 10mm was a bit much for an EDC gun.
https://www.gunpartscorp.com/products/983150

Load some of the Small Primer brass with Small Rifle primers and compare the two. I?ve heard some thoughts that the use of SRPs may result in less primer cratering. I have no personal experience with that as I haven?t located enough Small Primer 10mm brass to use.

I recently got back from the Sheriff's Department a 45acp Government 1911 that had been stolen from me almost 9 years ago.  Since I already had a Government 45acp I decided to convert this one to a multi-caliber Commander.  A 45acp Commander upper and a Commander upper for calibers 9mm, 38Super, and 9x23. I have a 10mm barrel for this slide, but I decided to go with a Full Sized, ie Government sized, slide for 10mm.
It's all put together, and ready for range testing.  I had previously had this slide and barrel combo on another frame, and it worked well and was accurate.
We shall see.

Quote from: The_Shadow on February 28 2022 12:48:01 PM MST
The use of "Small Pistol" primers in cases the usually use "Large Primers" primers started out because of "NON TOXIC"  NT primers that don't put lead vapors into the air for indoor ranges.

While many see this as a PIA for handloaders, it can be beneficial in times like these where primers are hard to come by in either size.

Agreed.  With small primer pockets, one can always use Small Rifle Primers.

My 10mm barrels(I have 4 by the same manufacturer) slug at .4007" and I size to .402". I don't believe I can go much bigger without affecting reliability. But. .402" seems to work very well. 
I think that you'd be better off tapping a bullet down the bore to measure the size than using a chamber cast.

Peter, PM sent.

If anyone is interested, Palmetto State Armory has TCBS 200 gr 10mm molds on sale, with free shipping.  I don't know how long this is going for.

https://palmettostatearmory.com/rcbs-bullet-mould-10mm-200-swc-82068.html

I converted my Springfield Mil Spec 45 acp to accept a 10mm upper using one of the Para Ordnance 40/10 slides from Sarco. As long as the slide goes on the frame, you are good to go.
I used a "drop in" 10mm barrel from Numrich that required finish reaming.
You might not need to change the ejector, but most 1911 10mm guns use a 38 Super. If you use the 38 Super ejector, and want to continue using the 45 acp slide, the slide will need to be modified to fit over the ejector.
Main Spring (Hammer Spring) should be upped to 25#, a Flat Bottom Firing Pin Stop should be added, and the recoil spring should be upped to at least 18 1/2#.
All in all, about $300 in parts.

Be aware that I have gotten two of the Para Ordnance 40/10 slides in Commander length. One worked just fine. One needed milling work because the rail cuts weren't wide enough for the frame.

In my 10mm 1911, I'm using an aftermarket, unsupported barrel. So far, no issues with the case support when using full power Underwood loads.

Currently I'm running a 25# Main Spring, with a Flat Bottomed Firing Pin Stop, and a 20# Recoil Spring in my Government sized 10mm.  I really didn't want to go over 20#, as that might cause frame battering.  My empties land about 15 feet away.

A little late to this thread, but I will post anyway.  I got two sets of the Harrison True Radius ignition kits.  One for my Rock Tactical 45 acp and one for my Springfield Mil Spec 45 acp. Both went in without "fitting", though technically they probably should have been fitted.  The Springfield got a very nice trigger pull, straight out of the box.  However, the Rock had some issues.  The sear wouldn't go into the sear cutout in the frame, until it was narrowed a bit. Apparently the sear cutout in the frame is not square, or wide enough.  Once it went in, everything worked as it should.  However, it's trigger pull is not as nice as that on the Springfield, so it probably requires some fitting.