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Kimber Ultra Carry 10mm conversion

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I got my Kimber Ultra Carry barrel back from getting it reamed to 10mm and went out to the desert to test it. Ran fine with several hundred rounds of factory Remington UMC 180 gr and about 100rds of Hornady 180gr xtp's. :banana:

I then shot some of my reloads, and had some issues. Had a few stovepipes, and even one shot where the case didn't even eject(never seen that one). Brass was ejecting 15 to 20ft. :huh:

Before going out I replaced the recoil springs with a 21lb spring kit. Guess I'll have to put in the 23lb springs. Gonna put them in tonight, and go out tomorrow or Thursday to see if the heavier springs help. I'm hoping this will solve the problem.


My reloads are:

180gr xtp's

11gr Blue Dot

new Starline brass

WLP primers


Does anyone else have this setup? Any suggestions? If I can't carry my full power carry loads, what's the point? right?





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There is a reason that there are no Officers style pistols in 10mm's made by the major companies like Kimber and Dan Wesson.

They start to get the same issues you discovered with your Kimber. Increased slide velocity with less slide mass (and shorter slide travel) makes for more challenges to get the pistol to run.

That said you might have to experiment a bit more with various powders/spring weights to find a hot load that will work.

Heavy power mag springs may solve the issue too: Remember that slide is movin' real fast and the rounds have to get up thru the mag fast too for reliable feeding.

This is often why we use extra power mag springs in our G20's when we run hotter loads.

You might luck out and pull it off.


There might be some guys here who have found what works.


When they were developing the 40 Super cartridge, they tried to put it on the small G30 frame. It worked about 2/3 the time without malfing.

That is why Lone Wolf did not offer a G30 length barrel for the 40 Super.

When I had mine back in 2002, I had talked to Dan at LW about this. He convinced me to stick with G21 conversion.


I feel your pain, as a short CCW in 10mm would be awesome.

Let us know if you get this baby up and running with full power 10 mm loads.

It's to pretty of a gun to be relegated to 40 S&W ballistics.


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I am no 1911 expert. Hopefully some of them will chime in and offer suggestions.


I have plenty of opinions though, so here are my thoughts.


Seems to me like you need to bleed off some energy early in that slide stroke, to get the slide velocity down, but without a really heavy recoil spring that reduces dwell time at the back of the travel, and increases velocity back into battery.


Increasing the mainspring strength will do this. The very first thing that must happen is the slide must push the hammer out of the way of it's travel. A stiffer mainspring will increase the resistance to slide movement right at the start, bleeding off extra energy.


Extra power mag springs may help get the bullets moved into position faster as well.


But, I could be wrong.

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I hadn't thought about getting stiffer mag springs. :blink: Thanks for the suggestion.

I know I will have to experiment to get it right. If my 180gr load doesn't work I'll try a different loading.

I guess I can work up some 155 grainers. Or 200, maybe 220 grainers! :wink:

At any rate, I'm gonna have fun doing it. :thumb:

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Thanks for the input.

Sounds reasonable to me.


Well, got the stiffer springs in. Damn, they are stiff. Pulling the slide back is kinda tuff.

If I can get out tomorrow I'll post my results.

Really hoping to make this setup work.

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Looks sweet. I'm thinking about a similar setup, how is it working with the stiffer springs?

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Try getting an EGW falt base firing pin stop as well. That will slow the unlocking time down some. That coupled with heavier recoil springs and a heavier main spring might do the trick.


If your not, trying using a duel recoil spring set up.

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Been busy lately, but had a chance to test the Ultra some more. For some strange reason the gun functioned better with the lighter stock spring. I am still using the same load for the testing.

Anyway, with the lighter spring I could actually make it through the whole mag (not every time) without any failures. Still not where I would like to be. Going to try mixing/matching the springs for a better combo. Factory Hornady 180xtp's still functioned fine with no issues. Going to still try to get the 11.0gr to run, if not, I guess I'll have to lower my load a bit. Gonna try 10.5gr instead of 11.0gr of BD.

After a couple hundred rounds thru this little baby, recoil becomes a factor....OUCH! :nt:


I'm also going to try these:


155gr xtp's

12.5gr BD



165gr fmj's (delta precision)

11.5gr BD





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Finally had some time to get my little Ultra running right. I am using the 165gr bullet with 11.2gr Blue Dot. I also got the 180xtp's to run with 10.8gr Blue Dot. I am using Metalform 7rd mags with stiffer springs and life is good. :thumb: I ended up using the stock dual spring recoil setup. It did not like the stiffer recoil springs. Going to finally get a chrony to see what kind of velocities I'm getting with these loads. As soon as I get time to run it, I'll post results.

Later. :salute:

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