I am having early slide lock backs. The slide is locking back with rounds still in the mag.
Kimber sent me a modified slide stop a month or so ago but I am still having them but less frequently. I got my Ultra Raptor at the end of April and have 1,119 rounds through it total so far. The outer recoil spring has 669 rd on it. The inner has 1,119 rds on it. I changed the outer at 450 rds just for the heck of it.
Since inserting the new modified slide stop, I went about 320 rounds malfunction free with Federal ball ammo. Last Friday I shot 200 rds of Speer fmj and had 2 slide lock backs. They occured after 90 rds at the range. It also did it once with some Federal HST 2 range sessions ago. (fyi HST jammed up really bad)
I have no plans to send it back to Kimber yet because they will test fire and find no problems and send it back. In all the malfunctions (about 19 total) I have had, I have never had one within shooting the first 50 rds at the range while the gun is clean. They all occur after about the 75th round at the range. I typically shoot 150 to 250 rds of fmj at each range session.
Kimber would have to shoot over 100 rounds or so to see the early slide lock backs, and I just don't see them doing that.
I plan to use a honing stone and shave off some more metal off the slide stop. Question: Is the slide stop the only or primary cause of this? Something else may be causing the early slide lock backs but I am only aware of the slide stop being the issue.
I am using Kim pro tac mags.
I experienced premature slide lock with two Kimbers; and filing/stoning the SS inner lug where there was copper residue took care of the problem in both.
Probably the one they sent you just needs a little more tweaking.
I'd fit the old one too, and have a spare.
Thanks Rick. I just want to make sure I am correctly diagnosing the problem.
I will try that and see.
If it's not a problem with the slide stop, I would check your grip. As you tire, it is possible for some part of your hand(s) to contact the slide stop during recoil resulting in slide lock. I find as I reach (and pass) the hundred round mark my grip requires more attention.
1 Bullets in the magazine contact the slide lock tab - adjust the tab with a small file.
2 Slide stop bouncing during recoil - use a round bur and your trusty Dremel to place a small detent in the back of the stop so the plunger can more securely hold the stop in the down position.
3 Your thumb is riding up under the stop while firing.
I will fire another 150-200 rds soon and be very careful. I want to rule out shooter error before it heads back to Yonkers to check the tolerances
Do you see any evidence on the slide stop lug that it is being bumped by the bullets?
How many rounds are in the magazine when premature lockback occurs?
Does the problem occur with both/all magazines?
See if weak magazine springs might be the problem by either replacing them, placing two rounds underneath the springs or trying other good quality magazines.
Please watch my video update: YouTube
My thumb was off the slide stop. When I first got the modified slide stop 2 months ago, it ran flawlessly for the first 350 rds or so of ball ammo. I remember the slide stop was a tight fit. Now it has loosened up, and that's when the premature slide lock started happening again. I have had 5 premature slide locks in the last 320 rds of ball ammo with WWB and Speer fmj 230 grain. There are copper scuff marks on the slide stop. I have already used a honiong stone to take off some metal before this range trip.
Should my Raptor take a 5-week vacation to Yonkers? Or should I continue to take off more metal from the slide stop?
I am thinking that as the slide stop has loosened up and broken in, it is bouncing more than when it was a tight fit.
The slide stop plunger should apply about 2 pounds of force to the aft end of the slide stop. How much does yours apply?
Have the plunger tube, spring and plungers been cleaned and oiled?
Are these slide stops the extended variety? If so, cut the extension off of one and see how it works.
Send it back or keep filing off the scuff marks? My answer's the same as Rick's was back in Post #2.
I friend wrote me with this comment: "...What concerns me is your noting the slide stop was initially hard to get out and has now "worn" a little and is much easier to remove. If the slide stop "binds" in the barrel link (that's what the part is that hangs off the barrel), the slide stop can be forced to rotate counter clockwise which "could" cause the slide to lock back if it happened at the "wrong" time..."
What do you all think of that scenario?
Unload your gun and remove the recoil spring to make the slide easier to manipulate. Is it possible for the slide stop arm to get rotated up (CCW) into its lock back notch in the slide by a link rotating CCW when the slide is about an inch away from starting to drive the barrel up into battery?
I removed the recoil spring and racked the slide slow and fast a few times with the slide stop in (and barrel in), and it did not move up or counter clockwise.
I think it's going to Yonkers
I have a new Kimber Eclipse Custom II 10mm, and I've had two premature slide- lock-backs, one on each of my first two trips to the range. On each of those range trips, I fired 50 American Eagle 180gr FMJ's, followed by a small number of hotter rounds. The failures occurred during the FMJ rounds. Both times, the next cartridge was slightly moved forward in the magazine, about 1/4". I pushed that cartridge back into place, dropped the slide, and everything was normal after that.
Did you also have that same symptom (next cartridge partially pulled forward)?
And did Kimber fix your problem?
I will get the Raptor tomorrow. Kimber shipped it out yesterday. I won't be able to shoot for about 2 weeks so I will not know if it is fixed. They said they fired several magazines of ball and hollow points with no issues.
Below is my entire Ultra Raptor history. I sent it back to Kimber primarily for the premature slide lock backs but also mentioned that I had a few failure to feeds. They received this list below.
Ok. For the failure to feeds, they said they replaced the extractor. I assumed they would just tune it but they said it was replaced. They said nothing about polishing the feed ramp. They also smoothed out the area of the aluminum frame just below the feed ramp for better round transition to the feed ramp. This area of the aluminum frame was chewed up and dinged from rounds hitting it. I am glad the feed ramp is part of the barrel in the ultra and not part of the frame as in the full sized. An aluminum alloy feed ramp would get chewed up I would think.
For the premature slide lock, they said they replaced the plunger tube assembly. They said something about a burr inside, and the plunger was not properly making contact with the slide stop. Nothing was said about replacing the slide stop but I'll check. I was having copper scuff marks on the slide stop, and I pointed that out in my note to them.
Well, hope that helps. My suggestion is to call Kimber and tell them you are having premature slide locks, and they will send you a modified slide stop free no questions asked. This has resolved the problem for some but not others like me. I really do not think mags have anything to do with this issue.
Range Trip 1 (250 rounds total)
50 rounds Remington UMC 230 gr FMJ No issues
50 rounds Federal 230 gr FMJ 1 failure to feed
50 rounds Sellier & Bellot 230 gr FMJ 1 premature slide lock
100 rounds Remington UMC 230 gr JHP 8 failures to feed
Range Trip 2 (100 rounds total)
100 rounds Sellier & Bellot 230 gr FMJ 1 premature slide lock
Range Trip 3 (100 rounds total)
100 rounds Federal 230 gr FMJ 1 premature slide lock
450 Rounds so far, contacted Kimber in May and received a modified slide stop to address the premature slide lock issue, also changed out outer recoil spring
Range Trip 4 (150 rounds total) (with modified slide stop)
50 rounds Federal 230 gr FMJ No issues
100 rounds Winchester White Box 230 gr FMJ No issues
Range Trip 5 (149 rounds total) (with modified slide stop)
149 rounds Federal 230 gr FMJ No issues
Range Trip 6 (170 rounds total) (with modified slide stop)
20 rounds Winchester PDX-1 230 gr HP No issues
50 rounds Federal HST 230 gr HP 3 failure to feeds, 1 premature slide lock
50 rounds Speer Gold Dots 230 gr HP No issues
50 rounds Speer 230 gr FMJ No issues
Range Trip 7 (200 rounds total) (with modified slide stop)
200 rounds Speer 230 gr FMJ 1 failure to feed, 2 premature slide locks
Range Trip 8 (120 rounds total) (with modified slide stop)
120 rounds Winchester White Box 230 gr FMJ 3 premature slide locks
Total round count:
rounds = 1,239 rds Inner recoil spring = 1,239 rds Outer recoil spring = 789 rds
Thanks very much for providing all that information.
I will call them ... I hadn't done that yet, because I thought they wouldn't be interested until I had put a LOT more rounds through it, but it sounds like from your experience that it's not the type of problem that resolves itself after break-in.
Good luck on your up-coming testing.
I forgot to ask you if you had seen the same symptom I saw: that the next cartridge had been slightly pulled forward, away from the rear of the mag, but still contained by the mag.
Yea, one maybe, but 2 premature slide lock backs your first 100+ rounds indicate some issue. This probably won't go away. The good news is that the modified slide stop may work for you. It has for others. And Kimber is aware of this, as this issue has been popping up over the years. Kimber will tell you if the modified slide stop does not fix the problem, you will need to send it back. Mine did not work. I was in denial and was determined to tinker and fiddle with it to fix it myself. In the end, I threw in the towel and gave up and sent it back.
Your question: I don't recall rounds being pulled forward. Some report that with a new mag, load it up to the brim with rounds and let it sit for a few days to break in the springs. But this mainly helped fix feeding issues for a new gun out of the box.
On my Kahr, the top round moves forward a bit. If a round is moving forward, it may be hitting the slide stop.
I ordered an additional mag from Kimber, and received it before my first range session (the new gun only comes with one). It appears to be essentially the same as the one that came with the gun, except the Kimber name engraved on the bottom plate looks slightly different... just a bit less distinct, and maybe a slightly larger font. It may be my imagination, but the spring tension SEEMS to be slightly weaker on the additional mag than on the one that came with the gun. (The 2nd failure was definitely when I was using the additional mag, but unfortunately I didn't establish which mag was being used when the 1st failure occurred (my bad).