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OdinIII

TTI +5/6 G34.5 mag tuning

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My new G34.5’s slide is failing to go all the way back when fired with 23 rounds loaded. It leaves the fired case in the barrel. The slide does go back but not far enough to eject.

 

I’m running 147 gr bullets at 132 PF with a 13 lb ISMI spring. I should also report that I had the same type of failure with the factory recoil spring with various numbers of bullets in the mag. I haven’t crono’d in a while but I did verify that my powder charge has not changed.

 

The 23rd round is very hard to load and seat the magazine. I’m assuming this is normal? Should the gun work as is? Any magic spring or follower work that should be performed? I need to change bullets anyway to coated to help with cost. Will 147 gr coated bullets change the energy in the slide from jacketed? Will 124’s or 135’s help? It seems that we’re having a lot of low 20ish round stages with steel and I really want to figure out how to make it run with 23+1.

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I think jacketed bullets are the least problematic in general.  Ours take 23 and work.  I would leave them loaded for a week and try it.  Maybe change to a different mag body and try that.  I have had good luck with ours in Gen 3 and Gen 5 Glock 34's running the same recoil spring about 130 PF 147 gr PD's.  Is the gun brand new?  Does it run flawless with factory mags?

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I haven’t shot any factory mags yet. It was unfired about a month ago when I put the dot on it. It’s got about 800 through it now. I’ve fired about 300 since replacing the factory spring with the ISMI and have had no issues with 22 or less in the mags.

I was surprised to have issues with the factory spring but found several post here about problems with the factory spring and 147’s at lower PF’s.

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So, you've had this issue with different amount of ammo in the mag?  It's not just the first shot with a fully loaded to 23 rndsag?

 

 

I'm shooting the same set up and ammo/of. I've had this malfunction too. I haven't been able to diagnose it. It doesn't happen often. Maybe 4 times in 8,000 rnds I've got thru my gen 5. I've kinda attributed it to my thumb contacting the slide. Though, I'm doubting that now.

 

 

I can't think of why bullet type or weight would cause this issue?

 

Edited by B_RAD

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So, you've had this issue with different amount of ammo in the mag?  It's not just the first shot with a fully loaded to 23 rndsag


I’m 99% sure the first failures was from minor 147 loads with the (over sprung?) factory recoil rod and spring. I know for certain it would choke with 23 rounds and the factory recoil spring with my hand very far away from the slide.

I haven’t had any failures with less than 23 in the mag with the 13lb spring. I only tried 3 times with 23 in the mag after the spring and rod change with the same result each time.

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I can't think of why bullet type or weight would cause this issue?


Maybe I’m barking up the wrong tree but thought I’ve read here of issues with 147’s being too soft for the factory recoil spring. I just thought since I need to switch to cheaper coated bullets anyway that I may be able to get more energy into the slide with a lighter bullet at the same power factor. I’m not sure it works that way though.

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9 minutes ago, OdinIII said:

 


I’m 99% sure the first failures was from minor 147 loads with the (over sprung?) factory recoil rod and spring. I know for certain it would choke with 23 rounds and the factory recoil spring with my hand very far away from the slide.

I haven’t had any failures with less than 23 in the mag with the 13lb spring. I only tried 3 times with 23 in the mag after the spring and rod change with the same result each time.

 

I've had it with 13lb spring and with ammo I know made PF and I'm pretty sure its happened on mags half empty mags. 

 

The first two-times it happened, I thought it might be because I was gripping the gun too hard and that somehow cuused it? Crazy. I had one of these malfunctions last weekend. Don't know what caused it. 

 

 

Edited by B_RAD

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2 minutes ago, OdinIII said:

 


Maybe I’m barking up the wrong tree but thought I’ve read here of issues with 147’s being too soft for the factory recoil spring. I just thought since I need to switch to cheaper coated bullets anyway that I may be able to get more energy into the slide with a lighter bullet at the same power factor. I’m not sure it works that way though.

 

More velocity would make me think the slide would travel faster and that seems to makes sense. Though, I'm not sure thats what's causing this. At least not in my case. 

 

Though, I guess my Chrono could have been off and maybe I'm not getting the 132 pf I thought I was?  I will check again. 

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I just realized I've had this malfunction with my practice mags. They all have Zev basepads.  So in my case, it's not the tti basepads. 

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I've had it with 13lb spring and with ammo I know made PF and I'm pretty sure its happened on mags half empty mags. 
 
The first two-times it happened, I thought it might be because I was gripping the gun too hard and that somehow cuused it? Crazy. I had one of these malfunctions last weekend. Don't know what caused it. 
 
 


That’s definitely concerning!

I know that I can feel the grip give when I grip my G48. I can see it deflect when gripped with no mag. I hope this isn’t the case but gripping the G34 may be changing the mag to slide interface. I still don’t see how it would matter enough to stop the slide without being stuffed completely full of ammo.

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18 minutes ago, OdinIII said:

 


That’s definitely concerning!

I know that I can feel the grip give when I grip my G48. I can see it deflect when gripped with no mag. I hope this isn’t the case but gripping the G34 may be changing the mag to slide interface. I still don’t see how it would matter enough to stop the slide without being stuffed completely full of ammo.

 

I'm just spit balling here. 

 

How dirty was your gun? I know mine is dirty right now. Could have been weak brass.amd it expanded more than usual. Maybe combination of several things. 

 

At the moment, I'm not concerned. 

 

If I keep having more issues then I'll worry. 

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It was a little dirty and dry during some of the failures with the factory recoil spring.

I had just cleaned and oiled it before the shooting session with the 13 lb spring where it still would not feed from a topped off mag.

I think the 13lb spring fixed everything but feeding from a mag with 23 rounds loaded

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3.9 gr of Unique with a 147gr Zero JHP. I actually averaged closer to 4.0 for 5 dumps when I checked it the other day.

That is a hair over 900 Ft/s in my Gen 3 34. It looks like I need to verify I’m getting something close to the same in this new Gen 5 pistol.

This same ammo is out of a ~1500 round batch. 500 of it went through the Gen 3 pistol with no issues but with only 10 rounds loaded for production. I tried last night and had to strain to get the topped off mags to seat in the older gun.

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27 minutes ago, OdinIII said:

3.9 gr of Unique with a 147gr Zero JHP. I actually averaged closer to 4.0 for 5 dumps when I checked it the other day.

That is a hair over 900 Ft/s in my Gen 3 34. It looks like I need to verify I’m getting something close to the same in this new Gen 5 pistol.

This same ammo is out of a ~1500 round batch. 500 of it went through the Gen 3 pistol with no issues but with only 10 rounds loaded for production. I tried last night and had to strain to get the topped off mags to seat in the older gun.

Regardless of what mag/ext you're using, a mag that's loaded to Max, is gonna put more pressure on the bottom of the slide. It might get better after the mag spring breaks in. You may also need to load to 22 to get 100% reliability.  I use tti basepads for my production mags. I can squeeze 23 in them but only load them to 22.  This is common for all mags that get loaded to max capacity. That's why you hear people talk about "22 rnds reloadable". 

 

 

There could be several things that cause a slide to short stroke.  The bullet type by it's self, is not something that would be on my radar. 

 

I would be looking for 

Limp writing

Bad brass (are you case gauging/still could be weak brass expanding/bulging too much)

Contact with slide

Light powder charge

Bullet ogive/OAL improper for barrel (have you plunk tested in barrel?)

Extractor slipping over rim during cycling. 

Edited by B_RAD

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I have this issue too with one of my guns.  It seems to be mag specific combined with the specific gun.  I.e. I KNOW mag 4 is going to cause me issues with my match gun and 23+1 in the gun.  Mag 2 is going to work fine at 23+1 and mag 4 is going to work fine in my practice gun.  I need to load up my problem mags to capacity and let them sit for a bit to see if the spring will set and allow that extra fraction of space to allow reliable feeding across all the mags/guns.

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I've never loaded with Unique, but my reloads will work fine with OEM recoil spring. Brass doesn't eject far, but still works. 

 

Try putting TTI extension on a different mag tube and see if it's easier to get 23rd round in. I've found it varies from 1 tube to another. I can get 23 reloadable with them if I try a few different tubes and see which allow a bit more room. 

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I have several interesting things to report.

 

I switched the new mag tubes I had bought specifically for the +5/6 base pads with my older non-ambidextrous tubes that I'd been using for production and it was definitely easier to load the 23rd round.  I had high hopes when I went to the range yesterday that it would be better.  It did seem better because the fired case always left the gun but it still would not push the round out of the mag.  I then chrono'd my ammo and averaged 129 PF with 3.95 gr of Unique and the 147 gr Zero JHP's.  

 

I then went 5 for 5 with a functioning 23+1 configuration with the first round being WWB 115 gr and 5 for 5 at 23+1 with the first round being Federal 115 gr FMJ.  I then tried the 147's with my old Gen 3 34 and it worked also at 23+1.  I guess this means that I'm just on the borderline with this Gen 5 pistol with my current load.  I didn't pay attention to which brand it was but the factory ammo averaged 133 PF for the 3 rounds I shot through the chrono.

 

I'm not too concerned now that I know how to make it work but I do plan to switch to a more mainstream powder and coated bullets so I can hopefully continue to afford to shoot.  That last 8,000 JHP order is sadly almost gone.  This experience makes me lean toward either 124's or 135's.  Hopefully whatever I settle on will work with the topped off mags.

 

I still plan to buy a backup pistol soon so I won't have to quit after a dot failure and would have already bought another G34 if I hadn't held that X5 Legion the other day.  I've already bought the parts to duplicate the current G34.5.  If I get another Glock it'll be interesting to see if it behaves differently.

 

 

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In my 17.4, I was loading 3.6 grains of TG , my 130 cast bullet, range brass, an whatever primers I could find cheapest. A gen 4 mag and TTI 140 always ran perfect, and I even reloaded to it a few times. I ran a factory recoil assembly, tungsten GR and 13# spring, and tungsten GR and 15# spring and never had a problem. 

 

As as far as the “limp wrist” argument goes, I have fired multiple glocks, 1911s, and other handguns with nothing more than my thumb around the back strap and my trigger finger on the trigger. None of them have failed to feed yet, and my 1911 with 45 Super ammo might have got away from me—but still fed the next round. 

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