Help with mag tuning

[Jan R.]

Hi all,

I have an old style SV 140mm tube that I use in an STI framed 38 super comp open gun. The mag is difficult to insert and wont drop free. I have the Dawson tuning Kit and have it returned to spec. It is better but still won't drop free and it needs a good shove to fully engage the mag catch.

Any suggestions would be appreciated.

Thanks,

Jan

[Jon Merricks]

Have you taken the top off the frame and take a look inside the grip with the mag in?

[Jan R.]

Hi John,

No I haven't. What should I look for?

Jan

Have you taken the top off the frame and take a look inside the grip with the mag in?

[Jon Merricks]

Does it go in without resistance or is it the same?

[Braxton1]

About a third of the way up the part where the mag tapers from "full-width" to "feed lip-width", check for HEAVY rub marks. If they're there, that part of the mag is actually hitting the metal part of the frame at the top of the mag well. You can relieve that area slightly on the frame and it should work better.

This is generally an issue with the newer SV mags inserted into STI frames, but the symptoms are there....

Edited April 27, 2012 by Braxton1

[Jan R.]

Thanks Braxton, I'll check that today. It's it my mag. I'm doing it for a friend so I'd like to keep all changes to the mag.

John

It is hard to insert as well.

Thanks guys!

Jan

[Jon Merricks]

I'd like to keep all changes to the mag.

Just because that is what you would like to do does not mean you will fix the problem. If the mag is with in spec and 100% functional you should not change the mag. Mark up the mag with either dykem or a black marker then insert mag. It should show you where the mag is rubbing.

[Jan R.]

Hi Jon

Thanks again for the reply. I mistyped in the post but I guess you got it. It's not my mag but I'm checking it in my gun. I've done only STI mags so I was just wondering if there were any special areas to pay attention to in the old style SV tubes.

Thanks

Jan

[Jon Merricks]

I would always sand the inside of the plastic grips when using SV mags in the STI's.

[Jan R.]

Hi Jon,

I do the same...

This is his 5th mag. He has four others of the same type that work fine...easy to insert, drop free, run well, etc.

That's what led me to believe that something was wrong with the tube, I just can't figure out what it is and it's driving me nuts!

Thanks,

Jan

[A63111]

I have had several do this. Take your calipers and measure ones that work to ones that don't. I my experience (your's may vary) it has been front to back. Put it in a padded vice and close it down a few thousands. You should immediately feel a difference. The ones that stuck for me were all over 1.380 front to back. Bring them down slowing into the 1.370 range and see if it helps. Just my experience YMMV.