Break-in 33-rnd Glock mag?

gloom

gloom

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What's the most reliable way to run a new 33-round Glock magazine in a new blow-back PCC before and after breaking it in? I read a suggestion to start at 60% capacity (20 rounds). After break-in, load 2 or 3 less than capacity if loading or reloading on a closed bolt.

I'm also curious how extensions affect break-in. Say, a 6 or 10 round extension. I'm guessing that when the original spring is used with a shorter extension, the tension is probably more manageable from the start. (?)

I decided to challenge the suggestions and cycle a fully loaded 33 on a closed bolt. My conclusion: Loading more than 30 probably isn't a good idea! haha (I can fix the bullet setback.)

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gloom said:
What's the most reliable way to run a new 33-round Glock magazine in a new blow-back PCC before and after breaking it in? I read a suggestion to start at 60% capacity (20 rounds). After break-in, load 2 or 3 less than capacity if loading or reloading on a closed bolt.

I'm also curious how extensions affect break-in. Say, a 6 or 10 round extension. I'm guessing that when the original spring is used with a shorter extension, the tension is probably more manageable from the start. (?)

I decided to challenge the suggestions and cycle a fully loaded 33 on a closed bolt. My conclusion: Loading more than 30 probably isn't a good idea! haha (I can fix the bullet setback.)

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So you hand cycled the rounds through? Once? How did you get so much setback?
 
I have never had issues with Glock factory 33 magazines. I noted the first 1 or 2 loadings were a bit harder but otherwise fine.
I have never had any luck with aftermarket 33 round magazines.
I have never had any luck with magazine extensions. There are all kinds of them out there so some could work better than others but I think it is best to avoid them.
 
I found it really hard to fully load my 33 round mags when they were new, I stopped trying when my thumb hurt a lot. Eventually either my thumb or the mags got used to it and now I load 33.

Seating a fully loaded mag on a closed bolt requires very firm motion, it you’re gentle it’ll fall out.

The mags are heavy enough for me, never tried an extension.

No idea what ”cycle a fully loaded 33 on a closed bolt” means, but having broken in the mag or not wouldn’t contribute to setback. If you were firing I don’t know how you’d have cartridges for the pic, and if you were hand cycling and get increasing setback as you went through the mag you have an ammo problem (insufficient tension) not a magazine or gun break in problem.

There is a lot of dumb stuff on the internet, stop reading it.
 
I have never even heard of breaking in a mag. Except for the purposes of making stiff springs easier to load, but certainly not for the reason you’re talking about.

I have several 33rd Glock mags and this has never been an issue in my AR9. If you’re getting setback, I would take a look at your feed cone, the geometry could be off and causing this issues. The first generation of Aero EPC-9 barrels had this problem and they changed the design and swapped out barrels for everyone who had already purchased.
 
Namerifrats said:
Looks to me like a ammo issue and not a magazine issue. If the rounds are properly crimped and there is proper case tension, it takes a lot to set a bulllet back. Likely the case will wrinkle before the bullet will seat further. Are these reloads?
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Not reloads.
 
Stogies said:
So you hand cycled the rounds through? Once? How did you get so much setback?
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Hand cycled once for each cartridge. I think the ones set back worst were the first to be cycled. Once I reduced the magazine from 33 to 31 or 30, it seemed fine.
 
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GymB said:
I found it really hard to fully load my 33 round mags when they were new, I stopped trying when my thumb hurt a lot. Eventually either my thumb or the mags got used to it and now I load 33.

Seating a fully loaded mag on a closed bolt requires very firm motion, it you’re gentle it’ll fall out.

The mags are heavy enough for me, never tried an extension.

No idea what ”cycle a fully loaded 33 on a closed bolt” means, but having broken in the mag or not wouldn’t contribute to setback. If you were firing I don’t know how you’d have cartridges for the pic, and if you were hand cycling and get increasing setback as you went through the mag you have an ammo problem (insufficient tension) not a magazine or gun break in problem.

There is a lot of dumb stuff on the internet, stop reading it.
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I'm using a UpLula to load the mags. The mags do lock in.

By loading on a closed bolt, I mean that the bolt is closed, I put the extra effort in to load the mag into place, then manually cycle the bolt. As opposed to inserting the mag with the bolt open and just releasing the bolt. I think I tried it both ways, actually. The bullet caught on something. Left a mark. heh
 
keepcalmandcarryon said:
I have never had issues with Glock factory 33 magazines. I noted the first 1 or 2 loadings were a bit harder but otherwise fine.
I have never had any luck with aftermarket 33 round magazines.
I have never had any luck with magazine extensions. There are all kinds of them out there so some could work better than others but I think it is best to avoid them.
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I do feel some spring pop when the mag starts to fill up. The 33 is a bit stiffer than a stock Glock 17 or 19 mag starting with the first round.
 
gloom said:
I'm using a UpLula to load the mags. The mags do lock in.

By loading on a closed bolt, I mean that the bolt is closed, I put the extra effort in to load the mag into place, then manually cycle the bolt. As opposed to inserting the mag with the bolt open and just releasing the bolt. I think I tried it both ways, actually. The bullet caught on something. Left a mark. heh
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Okay, so seating a mag on a closed bolt, that makes sense.
Then you’re locking the bolt back, releasing the bolt, repeat 32 times…correct?

None of that explains the setback with factory ammo.
Take a new round from the same box or batch, push it against a wood desk as hard as you can. If it moves you have a factory ammo problem. I’d also take a marker, or fingernail polish, and paint the projectiles on a couple bullets. Feed then through and see if you can tell if something is beating them.
 
GymB said:
Okay, so seating a mag on a closed bolt, that makes sense.
Then you’re locking the bolt back, releasing the bolt, repeat 32 times…correct?

None of that explains the setback with factory ammo.
Take a new round from the same box or batch, push it against a wood desk as hard as you can. If it moves you have a factory ammo problem. I’d also take a marker, or fingernail polish, and paint the projectiles on a couple bullets. Feed then through and see if you can tell if something is beating them.
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I didn't cycle through all 33 rounds since I only noted the problem within the top 2 or 3.

I ran a bunch of this ammo in a Glock 17 and it was fine. It was slightly odd though. It technically failed the plunk test, but I couldn't determine why.

I did find it to be true that there is so much spring tension when fully loaded that the body of the mag expands a little. They don't drop free when fully loaded. After removing a number of rounds, it will drop free.
 
Are these factory Glock mags?

Lets see pics of the gun. Include one with a loaded mag inserted with the bolt locked back. My guess is that the first few rounds are releasing early, right over the feed lips, and hitting the end of the barrel extension above the chamber, but without seeing the gun it’s hard to tell.

You could load a mag and then paint a stripe on the top bullet. Seat that mag with the bolt locked back, then release the bolt. Knowing the bullet orientation will help you figure out where it’s hitting.
 
Those projectiles should not have divots in them like that. Can you post a couple close-up photos of the feed ramp?
 
GymB said:
Are these factory Glock mags?

Lets see pics of the gun. Include one with a loaded mag inserted with the bolt locked back. My guess is that the first few rounds are releasing early, right over the feed lips, and hitting the end of the barrel extension above the chamber, but without seeing the gun it’s hard to tell.

You could load a mag and then paint a stripe on the top bullet. Seat that mag with the bolt locked back, then release the bolt. Knowing the bullet orientation will help you figure out where it’s hitting.
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Orientation before attempting to chamber. This one and a few more actually chambered without a problem, but they did get dents on the bullets.

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This one actually jammed against the outside lower face of the chamber or whatever that area is called. This is what is causing the massive setback. I did notice the mag move when I slowly tried to chamber this one. I think it just comes down to spring tension in the magazine affecting the entry angle, but it might not hurt if the bevel of the mouth of the chamber were a little smoother. I also noted that this jam happened with mag #2.

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Looks like the extractor took a little bite out of this one.

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Looks like the cartridge is getting our of the magazine ahead of the extractor causing the bullet to not align with the chamber. Could be caused by high upward pressure in the magazine, although I haven’t had that specific problem. Issue might be alleviated by the mag spring breaking in. Load it with 33 and let it sit for a week or two.
 
GymB said:
Looks like the cartridge is getting our of the magazine ahead of the extractor causing the bullet to not align with the chamber. Could be caused by high upward pressure in the magazine, although I haven’t had that specific problem. Issue might be alleviated by the mag spring breaking in. Load it with 33 and let it sit for a week or two.
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I also wonder if the extractor has an overly sharp edge or something. Only sent 100 rounds through the PCC so far, not even using the 33-rounders. During testing I think the most I loaded was 12 in a 15-round magazine. It just worked out that way.
 
Can’t tell from the pic, the back of the rim is clearly damaged by the extractor, is the front of the rim also damaged? Is there a notch cut all the way through the rim?
 
GymB said:
Can’t tell from the pic, the back of the rim is clearly damaged by the extractor, is the front of the rim also damaged? Is there a notch cut all the way through the rim?
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Just the rear face of the rim is damaged. Not too deep. Just annoying if planning to reload. heh
 
GymB said:
Looks like the cartridge is getting our of the magazine ahead of the extractor causing the bullet to not align with the chamber. Could be caused by high upward pressure in the magazine, although I haven’t had that specific problem. Issue might be alleviated by the mag spring breaking in. Load it with 33 and let it sit for a week or two.
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Yeah, I'm keeping them loaded and casually unloading and reloading them to loosen up the springs a little. I might need these ready to go in a week without much range time.
 
OP I would not worry about breaking the mags in too much. I run various cheap 30-35 round mags in a KelTec SUB 2000 and I did nothing whatsorever to break any of them in. I am close to a thousand rounds now and no malfunctions. A decent modern mag really should just work.
 
Stogies said:
OP I would not worry about breaking the mags in too much. I run various cheap 30-35 round mags in a KelTec SUB 2000 and I did nothing whatsorever to break any of them in. I am close to a thousand rounds now and no malfunctions. A decent modern mag really should just work.
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I'd usually agree, but if you take a look at the bullet setback that I photo'ed, I think it's a combination of this particular firearm and having long magazines. I bet that new Glock 19 or 17 magazines would work fine. Even then, the Extar company suggested loading them -1 if loaded on a closed bolt. At least to ensure that they lock in quickly and reliably. I think I tested them at 100% capacity without a problem, but I do keep them on standby with -1.
 
do you have any different bullet shapes or other mags to try? that looks like a geometry problem.
 
Catfish said:
do you have any different bullet shapes or other mags to try? that looks like a geometry problem.
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During initial testing it successfully ran 115gr and 124gr round nose, and 147gr truncated cone. Mostly out of a new Glock 19 magazine that wasn't full. (It wasn't intentional to not fully load the magazine. It was just based on the testing format that I was using.) I think I even tried some reloaded hollowpoints without a problem. Again, not from a full magazine.

I think it will be fine after running them a bit. It's feeling easier to manually cycle the action already unless I'm just getting stronger. haha
 
keepcalmandcarryon said:
It may also be a loose magazine well allowing the magazine to tilt and become misaligned
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I did notice a little pivoting forward and backward. The one that jammed did pivot as the round was stripped from it.

In the photo of the magazines, I can see that the angle of the cartridge is a little different in one. Those are 100% full. I'm going to compare the cartridge angles when they are not fully loaded. So far they seem to run when they're up to 90% full. I'll know for sure after tomorrow.
 
gloom said:
I did notice a little pivoting forward and backward. The one that jammed did pivot as the round was stripped from it.

In the photo of the magazines, I can see that the angle of the cartridge is a little different in one. Those are 100% full. I'm going to compare the cartridge angles when they are not fully loaded. So far they seem to run when they're up to 90% full. I'll know for sure after tomorrow.
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You can try wrapping one with tape to eliminate some play in the magazine well and see if that helps. A good non destructive test.
 
gloom said:
I'd usually agree, but if you take a look at the bullet setback that I photo'ed, I think it's a combination of this particular firearm and having long magazines. I bet that new Glock 19 or 17 magazines would work fine. Even then, the Extar company suggested loading them -1 if loaded on a closed bolt. At least to ensure that they lock in quickly and reliably. I think I tested them at 100% capacity without a problem, but I do keep them on standby with -1.
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You don't have setback if you cycle a round and fire it. That's only a thing if you keep chambering the same round over and over.
 
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Stogies said:
You don't have setback if you cycle a round and fire it. That's only a thing if you keep chambering the same round over and over.
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The larger and fuller the magazine is the more force is required to strip a round off. Once this force is greater than the force needed to tip the magazine forward and down you get a jam. That is why the first few do it then the issue goes away.
A tighter mag well will fix this I think.
 
keepcalmandcarryon said:
The larger and fuller the magazine is the more force is required to strip a round off. Once this force is greater than the force needed to tip the magazine forward and down you get a jam. That is why the first few do it then the issue goes away.
A tighter mag well will fix this I think.
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That all makes sense. One time it was the 2nd shot that jammed, but likely the same cause.

Got some interesting results over the weekend. I was able to run 115gr round nose loaded to 25 rounds in two magazines 4 times each in live competition. Worked flawlessly. Today I ran 30 rounds of 115gr without a problem. However... I had jams running 147 flat nose unless I reduced to 20 rounds, and jams unless I reduced 124gr round nose to, I think, 20 to 25. It seems that the heavier the bullet weight, the less ammo that I could load without a jam. Maybe just a coincidence? (Granted, the 147gr FLAT nose was likely to be more problematic to begin with.)


My guess is that if I just continue to run 115gr round nose, it won't be a problem. (It also fired 7 reloaded 115gr hollowpoints without an issue, but those were in a Glock 19 mag only loaded to 7.)
 
I wonder if this is part of the issue. "Some users have reported that .308 springs forced the rounds to feed too quickly, causing the cartridge to ram into the bottom of the breech face (nosedives)." I currently have a .308 spring with a solid 6.4oz buffer, 20.6oz total mass. Only seems to happen above 28 rounds or so though.

I'm going to test an 8.4oz extended buffer and standard carbine spring soon.

One time the PCC cycled, but felt odd. I found that it in fact chambered a round after smashing the bullet back into the case. I also noticed that the hammer wasn't reset because I tried to engage the safety before inspecting the chamber. That never happed before as far as I know. The magazine was loaded to 30 and it freaked after the first shot. Only one of two magazines had that problem, so I'll keep watch on that one.
 
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