Slide failure to lock open?

[Hammer Time]

So, I was at the range the other day with my new SP-01 Tac (about 500 rounds through it at this point) and twice the slide failed to lock on an empty mag over the course of shooting about 150 rounds. I was shooting Blazer Brass 124gr and Federal Eagle 115gr.

Possible factors:

1) This was the first time shooting the gun since I replaced the stock recoil spring with a #13 recoil spring from CZ Custom.

2) I recently started applying CGW moly grease to the slide rails, and it was about 20?F outside when we were shooting.

I wouldn't think that switching to a #13 spring would be significant enough to cause a failure to lock open - while it may be less spring weight than the over-sized stock spring, it's still a very reasonable recoil spring weight and not in the "ultralight" category imo. Ejection distance with the new spring was in the 6'-8' range.

As for the grease, CGW states that it has a usable range of -20?F to 300?F, so 40? above the minimum shouldn't have caused the grease to gum up excessively and cause enough resistance to cause a failure to lock. Nor did the slide ever feel sticky when I was manually racking while shooting. When I got home and disassembled the gun, the rails were completely clean and there wasn't any grit in there that would have caused this. At home, at room temps, the slide moves very smoothly.

I haven't been back to the range since to see if it's still happening, and it's really not that big of a deal, but any other thoughts?

[daved20319]

Clean your mags, and make sure the slide release is clean and moving freely.  Later.

Dave

[Hammer Time]

Clean your mags, and make sure the slide release is clean and moving freely.  Later.

Dave

Thanks, Dave. The combo of mags I was using that day were clean and/or brand new. Slide release is moving freely.

Like I said above, it's not that big of a deal (unless it persists) but I'm just racking my brain as to what would cause it, when everything seems to be functioning fine otherwise.

If it persists, I'm going to number my mags and see if I can pin it down to one mag in particular.

[Jmoser]

I bet combo of cold ammo and cold grease was just enough.  Service temp rating of lubes doesn't mean that they dont change consistency / viscocity etc; only that they will still lubricate at that temp.  Rest assured your grease was stiffer at 20 deg than at 65.

If your ammo soaked at 20 deg F long enough it may have been a bit lower pressure as well.  Powders can be temperature sensitive [ ask any bench rest shooter.]

Also cold lube on the slide stop may have kept it from engaging quick enough.

I have had rifles act up in sub freezing temps due to lube issues, replicated the issues by putting my trigger group in the freezer.  It happens.  In my case it was old original factory lube.

Test again on indoor range without changing anything.

[Hammer Time]

Thanks for chiming in, Jmoser. Having two previous sessions with the gun without this happening (once at an indoor range and once at an outdoor range at above freezing temps), the cold seems like the likely culprit in this case. I'm headed to AZ soon - looking forward to shooting in warmer temps!   

[Bossgobbler]

Only two things can cause this. #1 slide not fully cycling, #2 thumb is riding the slide stop sometimes.

[Hammer Time]

Only two things can cause this. #1 slide not fully cycling, #2 thumb is riding the slide stop sometimes.

Yup, I'm gonna go with Door #1 on this one - failure to cycle due to low temps affecting the rail grease and/or ammo pressure.

[dbarn]

Mine was caused by inadvertently riding the slide stop with a high grip. The Rami slide stop absolutely fixed this problem. YMMV

[Earl Keese]

Mine was caused by inadvertently riding the slide stop with a high grip. The Rami slide stop absolutely fixed this problem. YMMV

Yep, easy way to confirm is to shoot one handed until mag is empty.

[cntrydawwwg]

  Just curious how much grease was used? The CGW molly does work at colder temps, but in a very light application.
   Ive tried it out in cold temps, and while it worked fine, I still prefer using my Breakfree during the winter. Just a personal thing for me, hunting in 0- -20 weather, used to use Rem. Oil and had a bolt freeze shut. Have never had anything freeze up using Breakfree. So it?s what I trust in cold weather.
    Not saying that was your issue, but does sound like a likely possible culprit.

[hansb57]

I would think that after 150 round the grease on the slide should be no factor anymore. I had the same problem after changing springs. I changed back And probleem was gone. I'm not saying its the spring but I always go back To a know working setup To make sure thats not the probleem.

[Hammer Time]

  Just curious how much grease was used? The CGW molly does work at colder temps, but in a very light application.
   Ive tried it out in cold temps, and while it worked fine, I still prefer using my Breakfree during the winter. Just a personal thing for me, hunting in 0- -20 weather, used to use Rem. Oil and had a bolt freeze shut. Have never had anything freeze up using Breakfree. So it?s what I trust in cold weather.
    Not saying that was your issue, but does sound like a likely possible culprit.

Minimal grease, applied sparingly with a toothpick. I'm going to keep working on isolating the various factors over the next several range sessions, but if I can't pin it down to anything else, I'll clean the grease off and go back to Breakfree or Ballistol, at least until Spring.

I would think that after 150 round the grease on the slide should be no factor anymore. I had the same problem after changing springs. I changed back And probleem was gone. I'm not saying its the spring but I always go back To a know working setup To make sure thats not the probleem.

Yeah, and while the ambient temp was around 20?, the gun was certainly warmer than that through the course of shooting 150 rounds.

Riding the slide wasn't a factor. My thumbs were well clear of the slide and I've shot this gun before without issue.

I'm likely headed back to the range tomorrow, and temps will be about the same, so we'll see what happens...

[1SOW]

 The pistol should run smoothly with a 13# recoil spring.  Hot ammo  will toss the brass well over 8 feet.  Weak ammo will toss shorter distances, 
Unless the spring is mismarked or damaged,  it's not the base cause of the problem.  11# springs will also cycle smoothly.  The Custom competition  pistols  often come with 11# recoil springs.
 

[Hammer Time]

Just an update - shot at temps of about 15-18?F today, and no issues with the slide failing to lock at all.