G-35 Doublefeed Problem

[sslav]

For the last two matches I've had doublefeed problems. Seems somewhat coincidental with a switch from Zero JHP to Rainier FMJTC though I am not sure that thats the cause. Strangely this seems to mannifest at matches and not in practice even though I fire more rounds in practice.

At the last match a more experienced shooter observed that my OAL seemed to be high. When I got home I remeasured a random sampling of rounds and they all came in at about 1.135-1.137 ballpark which I thought was fine for a Glock. In any case I loaded up a new batch at 1.125 and went to the range. The only difference between what I do in practice and at a match that I thought could be a factor was how many rounds I load in the magazines. I load 10 at a match and 6 in practice. So for this I was loading 10. No doublefeeds in 400 rounds but I am still not feeling too comfortable.

So my questions are as follows:

1. Could the geometry of a TC bullet combined with 1.135 OAL be a cause of doublefeeds while a JHP loaded to the same OAL did not?

2. Is the higher number of rounds in a magazine and a resulting higher upward pressure from the magazine spring a contributing factor?

Or if those are not the cause, then what else could it be?

[chp5]

The only way to tell for sure is to keep shooting the rounds with your shorter OAL. Your prior OAL is slightly long for a Glock, but not terribly so. I load to 1.125 OAL.

IMO, you should fully load your mags in practice (at least most of the time). Otherwise, you don't know if they run.

[Viggen]

It could also be the age of the magazines - with a lot of use the feed lips on Glock mags will distort and open up a bit. That along with a 1.135 OAL and it might be enough to cause a hiccup.

Just a possibility.

I also generally load to 1.135 - mags get old and the feed lips can move.

Maybe something to consider, maybe not.

[Nik Habicht]

Slav,

my money's on the geometry of the truncated cone heads combined with the length the JHPs used to function at. I've seen this problem switching from a narrow ogive JHP (close to a fmj bullet) to a wide ogive JHP. In fact, when I was having ammo issues years ago, Olhasso told me I was loading too long --- and he was right. Going shorter made everything work perfectly --- at least in the 132-135 pf production loads we're talking about.

Last but not least: Practice like you'd load your gun in a match --- 11 to start, ten in any reload mag. If you're going to have issues you want to see them in practice. And try some weakhand stuff --- because if the gun runs there with 11 rounds, it'll run anywhere else....

[Flexmoney]

Is the problem with the last round in the mag?

[sslav]

Is the problem with the last round in the mag?

No, actually the opposite after a reload or the initial load the first shot goes off, and when the slide cycles for the first time a doublefeed occurs.

Slav

[Flexmoney]

Are they 10 round mags?

[sslav]

Are they 10 round mags?

15 Round mags that I load to 10.

[Flexmoney]

hmmm

Bullet profile is likely as important as OAL.

Had your gun apart in the last month or two?

Can't hurt to break the mags down and clean them.

And, check the feedlips. Matt at CGR has the specs: http://www.custom-glock.com/magtech2.html

Shooting Major or Minor?

Extended slide lock/release?

[sslav]

hmmm

Bullet profile is likely as important as OAL.

Had your gun apart in the last month or two?

Can't hurt to break the mags down and clean them.

And, check the feedlips. Matt at CGR has the specs: http://www.custom-glock.com/magtech2.html

Shooting Major or Minor?

Extended slide lock/release?

I take it apart every 500 rounds or so for cleaning. So deffinitely had it apart a couple of times in the last month.

After the latest batch of doublefeeds I tore down and cleaned the mags.

Just measured the feedlips - .374, .376, .376, .378, .380. So .004 - .01 over the top of the reccomended range. Is that too much or acceptable?

Shooting minor.

I do have an extended slide lock, but I shoot lefthanded so no accidental contacts with slidelock.

Just shot a short match tonight - no problems. So I am keeping my fingers crossed and hope that either the shorter OAL or mag cleaning did the trick.

Edited December 16, 2006 by sslav

[TruStreet]

hmmm

Bullet profile is likely as important as OAL.

Had your gun apart in the last month or two?

Can't hurt to break the mags down and clean them.

And, check the feedlips. Matt at CGR has the specs: http://www.custom-glock.com/magtech2.html

Shooting Major or Minor?

Extended slide lock/release?

I take it apart every 500 rounds or so for cleaning. So deffinitely had it apart a couple of times in the last month.

After the latest batch of doublefeeds I tore down and cleaned the mags.

Just measured the feedlips - .374, .376, .376, .378, .380. So .004 - .01 over the top of the reccomended range. Is that too much or acceptable?

Shooting minor.

I do have an extended slide lock, but I shoot lefthanded so no accidental contacts with slidelock.

Just shot a short match tonight - no problems. So I am keeping my fingers crossed and hope that either the shorter OAL or mag cleaning did the trick.

I measured my new mags and they are .360. The reason I bought them was that I was having the same issues that you are having. I was told to use robogrip pliers with the rubber tips on my old mags and squeezed them to .365, they now work like a charm.

[SA Friday]

Slav,

my money's on the geometry of the truncated cone heads combined with the length the JHPs used to function at. I've seen this problem switching from a narrow ogive JHP (close to a fmj bullet) to a wide ogive JHP. In fact, when I was having ammo issues years ago, Olhasso told me I was loading too long --- and he was right. Going shorter made everything work perfectly --- at least in the 132-135 pf production loads we're talking about.

Last but not least: Practice like you'd load your gun in a match --- 11 to start, ten in any reload mag. If you're going to have issues you want to see them in practice. And try some weakhand stuff --- because if the gun runs there with 11 rounds, it'll run anywhere else....

Beat me to it Nik. +1 on the ogive of the different bullets.

Another factor may be the crimp on the Reiners vs the crimp on the Zeros. I played around with Reiners and found the crimp I was using for the Zeros was too much and had to back it off for the plated bullets. I then had some issues with the outer edge of the casing mouth sometimes catching while feeding.

[sslav]

Slav,

my money's on the geometry of the truncated cone heads combined with the length the JHPs used to function at. I've seen this problem switching from a narrow ogive JHP (close to a fmj bullet) to a wide ogive JHP. In fact, when I was having ammo issues years ago, Olhasso told me I was loading too long --- and he was right. Going shorter made everything work perfectly --- at least in the 132-135 pf production loads we're talking about.

Last but not least: Practice like you'd load your gun in a match --- 11 to start, ten in any reload mag. If you're going to have issues you want to see them in practice. And try some weakhand stuff --- because if the gun runs there with 11 rounds, it'll run anywhere else....

Beat me to it Nik. +1 on the ogive of the different bullets.

Another factor may be the crimp on the Reiners vs the crimp on the Zeros. I played around with Reiners and found the crimp I was using for the Zeros was too much and had to back it off for the plated bullets. I then had some issues with the outer edge of the casing mouth sometimes catching while feeding.

Loading to 1.125 OAL seems make the problem go away. I think I am going to switch back to Zero JHPs anyway.

[chp5]

Loading to 1.125 OAL seems make the problem go away. I think I am going to switch back to Zero JHPs anyway.

Glad to hear it.

[HK Dan]

Are you running low-powered loads? If so, up it a bit and see what happens. Sometimes the difference between powder measure throws can put a low end round below the threshold and make it look like a double feed, when what's happening is not having enough power to eject the spent case.

This happened to my G35 with a 9mm conversion barrel and low end 9mm rounds. It is frustrating, but a little extra powder fixed it all.

I use the same bullet, same OAL (1.135) and same gun. I use RCBS dies on a Dillon 550b and crimp when I seat. This setup has worked virtually flawlessly for me.

HK Dan