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When I completed a string of fire on a tactical training course last Friday, I noticed that the central rod that the captive recoil spring assembly is built around was loose on my Kimber Ultra Carry I. Closer examination showed that the rod had broken at its connection to the rear endplate, as shown below. The parts in the upper portion of the photo are the broken assembly. An intact assembly is shown in the lower portion of the photo for comparison (with a Kimber disassembly tool attached.)



I had already replaced the outer recoil spring once at around 2500 rounds, and was planning to replace the entire assembly at the end of this month because I estimated I would reach approximately 5,000 rounds fired at that point. It appears I have shot more than my estimated average rounds per month allowed for, and recalculation indicates that the gun is actually closer to 6000 rounds fired.

A call to Kimber revealed that their recommended recoil assembly replacement intervals are:

1800 - 2500 rounds - outer recoil spring
4500 - 5000 rounds - full recoil spring assembly.

They also suggested replacing the firing pin / firing pin spring and mainspring housing at 5000 rounds, and examining the alloy frame for any cracks in the dust cover area.

To Kimber's credit, they are sending me a new recoil spring assembly at no cost under warranty.

Going forward I plan to keep a log of rounds fired and to replace the parts at the lower threshold of the recommended intervals to prevent a recurrence.

Others who own compact Kimbers with captive recoil spring assemblies may want to contact Kimber about replacement intervals for their particular guns and order parts before replacement thresholds are reached to prevent failures like the one illustrated here.

Good pictures/description. As many Kimbers as there are out there - and many people depending upon them - definitely "should know" info.

Did the gun continue to function or did it stop? I guess I should keep a spare assembly in my range bag.

HighVelocity wrote:Did the gun continue to function or did it stop? I guess I should keep a spare assembly in my range bag.

Good question...

I have about 800 rounds (guesstimate) through my UCII right now. I'm thinking of just going ahead and buying a spare assembly for the same reason. I'll keep an eye out for cracks in the dust cover, but why would Kimber recommend changing out the mainspring housing at 5,000 rounds? I confess that I'm ignorant enough to not know why a mainspring housing would fail at all.

Kimbers come with a plastic mainspring housing. Even my Ultra CDP did. The only Kimbers that have metal mainspring housings from the factory that I am aware of are the ones that come with a magwell. Every Kimber I have owned got a checkered steel mainspring housing installed immediately.

Did the gun continue to function or did it stop? I guess I should keep a spare assembly in my range bag

When I saw the failure, I didn't attempt to fire it again because the unpredictable alignment of the now loose pieces of the formerly captive recoil spring assembly could have caused the gun to seize in mid recoil with unknown results other than probable damage to the gun, and possibly to me. The failure was detected on the last round, with the slide locked back. I'm pretty sure that's when the failure occurred, because the central assembly rod was hanging loosely about 3 inches in front of the muzzle after it became detached from its rear plate. Another shot would almost certainly have caused it to fall from the gun.

Since it happened during a training session, there was no upside to that risk. If I had been in the midst of an armed encounter and I needed to fire again, I would have taken the chance hoping that the springs would have lined up sufficiently in the very limited space to allow the slide to retract. I don't know if I would have gotten more than 1 shot out of it in this condition.

I already had a new recoil spring assembly in stock because I knew replacement time was coming up, but I didn't have it in my range bag, so I was out of luck for the remainder of the training opportunity that day.

Another point worth mentioning is that if you let the outer recoil spring (the 1800 - 2500 round one) get seriously beyond its recommended replacement time, intermittent and then increasingly frequent failures to extract and / or eject in a previously 100% reliable gun will help you remember.

I should also point out that these issues are not a knock on Kimber or the design or reliability of the Ultra Carry. Use of a carefully engineered captive recoil spring assembly with one short heavy spring outside and another tightly coiled spring with smaller diameter inside is the best way manufacturers have found to shrink a major caliber weapon envelope into the size of the Ultra Carry. This arrangement is less durable than the single long spring system used on full sized 1911's. This is a simple engineering fact, and not an issue if care is taken to follow the manufacturer's recommendations on maintenance. (There is no free lunch). Kimber was also gracious in sending me a new recoil spring assembly under warranty even though I had exceeded their recommended maintenance interval.

My takeaway here is to be careful to monitor the number of rounds fired over time in my guns(not hard with a 3x5 card and a pen in the range bag - even full size guns have similar recommended spring replacement guidelines) so I can consistently perform the recommended maintenance at the most conservative intervals in Kimber's recommendations.

Some folks, including armorer course instructors for Glock, Sig, etc., suggest simply scheduling recoil spring replacement on your appointment calendar once a year. This will keep you covered if you average no more than 200 rounds per month. If you shoot 400 rounds per month, just schedule replacements every 6 months. That's the system I had been using, but a few of my friends talked me into going out quite a bit more and shooting a lot in the last 4 months, and it wrecked the validity of my estimation system before I realized how far it had gotten out of whack.

The Ultra Carry is a very fine defensive weapon that is accurate, light, concealable, and very easy to shoot well. I will continue to rely on it for resolving serious social situations when nothing less will do.

I have a few Springfield's with the same design. I knew about Kimbers recommendation on replacement, but I don't remember the same from Springfield. I'll have to look it up later. What I don't understand is why Kimber sells a fairly pricey pistol with a plastic part that requires replacement where a metal part would more than likely last a lifetime. Very frustrating.

The Annoyed Man wrote:

HighVelocity wrote:Did the gun continue to function or did it stop? I guess I should keep a spare assembly in my range bag.

Good question...

I have about 800 rounds (guesstimate) through my UCII right now. I'm thinking of just going ahead and buying a spare assembly for the same reason. I'll keep an eye out for cracks in the dust cover, but why would Kimber recommend changing out the mainspring housing at 5,000 rounds? I confess that I'm ignorant enough to not know why a mainspring housing would fail at all.

It shouldn't fail, the captive recoil spring assembly should not fail...and the dust cover should never crack.

Springs (because of cycling) will naturally become fatigued and no longer perform to specification, this is normal and to be expected. The rod that holds the springs in place however should NEVER fail. If you call Kimber and ask...you might find that the part is a "MIM". If it is....then there is your answer.

Para Ordnance also had a problem with the end plates coming off of captured spring assemblies, they finally got it sorted out.

The rod that holds the springs in place however should NEVER fail. If you call Kimber and ask...you might find that the part is a "MIM". If it is....then there is your answer.

I didn't ask Kimber if the part was a MIM, but I don't believe it is. It looks to be machined from bar stock.

The point of failure was the smallest diameter section of the rod, which appears to be threaded where it mates with the back plate. This apparently creates a point of diminished strength.

If you replaced the outer spring assembly - is it possible you overtightened the guide head onto the recoil rod during the spring replacement? Supposed to be just tight with locktite on the threads. I snapped one off once during a spring replacement. Just asking - not 'pointy fingers'!

I wonder what Wolff recommends for their assembly as I replaced mine within the first 100 rounds to a heavier 21# setup. That alone cured my FTGB problems immediately, plus I noticed that all of Wilson's guns use 22# springs.

If you replaced the outer spring assembly - is it possible you overtightened the guide head onto the recoil rod during the spring replacement? Supposed to be just tight with locktite on the threads. I snapped one off once during a spring replacement. Just asking - not 'pointy fingers'!

I have to say it's possible, because I have no way to rule it out. During the outer spring replacement I carefully followed the instructions Kimber provided. I don't recall any torque specs being included. Since the part lasted approximately 3500 rounds after the spring replacement (in addition to about 2500 before the spring replacement) and the Kimber folks didn't seem surprised at the issue or go into the reassembly procedure I used when I replaced the outer spring, I'm not leaning toward that as a likely cause. I think the issue is simply that I continued to use the part beyond its rated service life.

Thanks for the info. I'll be getting a spare assembly for my CDP Pro