STI 2011 Mag issues

[jonb.]

I have 4 sti mag tubes.

13 coil grams with grams comp followers.

1 Dawson SNL pad

3 Dawson +1 pads

Here's the breakdown.

MAG 1 (bought used) has SNL base pad holds 20 non-reloadable I use this for my first mag. It is hard to seat and will drop free when mag is down to 17 rounds, when the mag is at capacity it will not drop free.

(all the other mags have +1 pads)

MAG 2 (bought NEW) magazines holds 20 reloadable drops free at capacity.

MAG 3 (used) holds 17 reloadable 18 not reloadable does not drop free with 18 rounds but will drop free at 17.

MAG 4 (USED) Behaves the same as mag 3.

So I think the tubes I bought used are out of spec. Any suggestions on how to tame them and get them into spec? I attempted to tune the mags but the one I tuned holds more but is very hard to seat and will not drop free until I hit 17 rounds in the mag.

From what I have read is that the Dawson tuning kit will not help me in squaring these mags up which is what I think is the issue.

LAST THING the mags function perfectly in regards to feeding the gun I tuned all my lips so my lips are awesome!

[Poppa Bear]

So you bought and installed the Grams followers and springs?

[jonb.]

So you bought and installed the Grams followers and springs?

Followers were from my old Mags which functioned 100%. Springs are new. I can't manufacture new mags here in CA I can only rebuild and repair. Old tubes needed to go the feed lips were no longer amazing.

Edited December 24, 2012 by jonb.

[calvinc78]

I might be wrong but with the capasity your saying you have 140mm or 126mm? now I see your useing grams 13 coil springs? now I've always been told you want 11 coil springs with that size..... I could be wrong... I know that wont cure your mag tube issue but just noticed that when reading

[jonb.]

140mm my old tubes used the 13 coil without an issue.

[tjs375]

I use 11 coil on my 140's, 13 coil on 170's. Never ran into any problems. Read the mag tuning tutorial on the FGW page in the venders section. Hope this helps.

[Jaxshooter]

I don't think it is a spring issue. I run 13 coil springs in my mags and they drop free loaded to capacity (20 rounds). Sounds like the mag tubes are binding in the grip. Mark the mag bodies with a marker or something similar. Seat the mags and release them and see where they are rubbing in the grip. Then you can use a vise to squeeze the mag tubes to keep them from binding. Don't crank down on the vise just squeeze them a little at a time and try them.

[jonb.]

I don't think it is a spring issue. I run 13 coil springs in my mags and they drop free loaded to capacity (20 rounds). Sounds like the mag tubes are binding in the grip. Mark the mag bodies with a marker or something similar. Seat the mags and release them and see where they are rubbing in the grip. Then you can use a vise to squeeze the mag tubes to keep them from binding. Don't crank down on the vise just squeeze them a little at a time and try them.

With the rounds in them?

Also how much of the ribs do I grind down on the inside? With my dremel I can only reach the bottom half inch or so.

[z40acp]

I got some STI mag tubes a couple of years ago that were very hard to load the last 3-4 rounds and could not get full capacity out of them. Sent them to Chris at STI and he stated they were out of spec at the top where the taper is. He adjusted them smaller front to back which made the side to side bigger. I have seen the front to back spec on this forum before but can not locate it now. As stated above, squeeze them in a vise to match one of your old tubes.

[jonb.]

I got some STI mag tubes a couple of years ago that were very hard to load the last 3-4 rounds and could not get full capacity out of them. Sent them to Chris at STI and he stated they were out of spec at the top where the taper is. He adjusted them smaller front to back which made the side to side bigger. I have seen the front to back spec on this forum before but can not locate it now. As stated above, squeeze them in a vise to match one of your old tubes.

They will be on the way to Randy at STI on Monday. Problem solved.