CZ TSO 9mm, first round not chambering

[mpmo]

Shot two matches this past weekend.  At LAMR, racking the slide to chamber the first round, several times the round did not completely chamber and I had to slightly push the slide forward to chamber.  After that first round, no issues with feeding.  Not sure what is going on with this.  The biggest variable I can find is that the weather is now colder here.  Normally shooting in 60-85F degrees.  This weekend it was 43-49F.  After I got home I did plunk test a few rounds just to make sure that wasn't the issue and they plunked fine.  I did test to see if it will chamber in the warm at home.  I'm not crazy about chambering rounds unnecessarily in my house, esp if there is an issue with the gun.  Tonight I'll try chambering some without primers and powder and see what that does.

 

Gun cleaned around every 500 rds.  Bore snake pretty much after every time after I shoot.  Rails, and touch points oiled about every time before I shoot.  Probably 4,000 rds through gun, 6 months old.

 

2 different rounds.

Both new Starline brass.

BB 124g RN, and Berry's 124g RN.

All rounds tested in Hundo case guage before boxing.  

 

Any ideas what is going on?  Or other variables or something else I should be doing?

 

 

[Lowsc3]

Is it with a mag loaded to max capacity? Try taking one round out of the mag and see if that will solve it. Some times there is to much tension when you shove that absolute last round in the mag and the recoil spring may not have the power to overcome that friction entirely. 

[muncie21]

The type/weight of oil you're using in conjunction with the weight of your recoil spring can make a huge difference when the weather gets cold.  Either try a lighter weight/different brand oil and/or increase the weight of your recoil spring.

[858]

Cartridge overall length? My TSO and CM dislike longer 9mm cartridges with unmodified magazines. The feeding problem is less pronounced when the magazine isn't loaded to capacity. Unless you lubricated the pistol with heavy grease I don't think oil will slow slide velocity enough at 40 degrees F to alone cause feedway stoppages.

[mpmo]

Yes, Mag was loaded to capacity.  Recoil spring is the lightest it came with, 11lb I believe.

 

Went to an indoor range after my gun had been at room temp for a day.  Loaded mags to 5 rds and also to full capacity.  I did not have any issues.  It still felt like it was struggling to feed the first round, like the slide was moving slower, struggling a bit, but they all fed.

 

I'm going to say the cold weather.  I will do a full clean before my next outdoor cold competition and see if that helps.   The oil I'm using is Wilson Ultra Lube II standard.  I might want to try some of the lite.  

 

[Superkaratemonkeyfighter]

This Might sound stupid but 

rack the slide like you hate the gun. 

No gentile motion , or don’t let your hand follow the slide back. 

[Eric_T]

I like Lowsc3's theory, seems to make sense since it only happens with the first round.  It would be interesting to see if there's a difference between full mags and partially-loaded mags when the gun is cold.

[WildPete]

Download one round and give it a try. Do you have base pads on your mags?

[Lowsc3]

On 10/29/2020 at 9:14 AM, Eric_T said:

I like Lowsc3's theory, seems to make sense since it only happens with the first round.  It would be interesting to see if there's a difference between full mags and partially-loaded mags when the gun is cold.

I have the czc base pads and springs and I can load 21 but its to tight and I'd rather have the reliability and ease of reload. I usually also have a fourth mag I use for solely plus one on the make ready.

[kalaikanui]

I ran my new S2 OR this weekend and had some similar issues on the first two stages (very cold, 11# recoil spring) and was loading my new Henning extensions to 23 at first. By the third stage I had started downloading one round (to 22) and didn't see the problem any more. My .02 is mag spring tension was too tight on new mags, as the gun seemed to run fine otherwise.