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140mm STI Mag Tuning


Mark K

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At Area 6, I picked up an STI 140mm Mag tube. I brought it home, ran it in my case vibrator for a couple of hours to polish it up. I then took a follower and IMSI 11 coil spring that I took out of my SVI mag when I changed over to Gram's followers/springs. I then capped it with a Dawson +1 basepad. I shoot 40cal loaded out to 1.25 OAL. With my SVI mags I can load 18-19. With this STI, I cannot get more than 13 rounds in.

Suggestions?

Not a really big deal, I can use this one for my Barney mag. Just curious.

Mark

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Measure the outside width of the mag, I'll guess it is something like .930" wide, that combined with deep grooves on the side will bind them up hard.

The other thing it could be is a Super mag, if it has deep grooves on both sides it is a Super mag, deep on one side and shallow on the other is a 40 mag.

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I have a Dawson Tuned mag that does that. Try bumping, may have to bump it hard, the mag on a table as you load another round doing that I can get 19 or 20. Once loaded it runs fine. I don't use it much because it is a pain in the butt to load. If that works it is probably the demensions are off.

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If it is the correct 40 mag, look at the width of the mag at the top just above where the taper is. My son bought three new mag tubes from Chuck Bradley and when he got to 13 or 14 they were very hard to push the bullet down. They would only hold 16. This was even when we used everything out of one of my mags {Grams follower, spring and 4mm base pad} and mine hold 20. We sent them back to Chris at STI and they fixed them. He said they were too narrow at the point above the taper. Now they hold 20. Call STI and ask for Chris.

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Thank you all for the advice.

Boz - yeah, 140mm, same length as all my others.

Merlin - having it work with shorter rounds is of no use to me (I would try it, but I am too cheap to waste 20 rounds by shortening them)

Howard - I will look at the grooves and measure when I am home at lunch.

CenTX - Yeah, last night I bumped and slammed and used one of those LULA mag loader helper thingies, and was able to get 18 in, and they seem to come out OK, but hell it was a lot of work.

z40acp - Thanks for the contact, I just may do that.

Mark

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Measure the outside width of the mag, I'll guess it is something like .930" wide, that combined with deep grooves on the side will bind them up hard.

The other thing it could be is a Super mag, if it has deep grooves on both sides it is a Super mag, deep on one side and shallow on the other is a 40 mag.

That's nice info there. I'd wondered how to tell them apart in case they were to get mixed up some how.

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Why are you loading 40 s&w to 1.250 anyway?

I bought the gun (Lightly Used). I was told that the gun and 5 mags were setup for that length cartridge. With the gun I bought 2000 rounds of Atlanta Arms Ammo loaded to that length. All of it has functioned flawlessly (except some of my learning issues with reloading/resizing brass). I have worked up loads for 165, 180, and 200gr bullets with 1.250 OAL that meet the PF.

SO, if it is working..........

??

Mark K

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I run 1.230" in my guns, I don't need to but that is what I run. My guns will run from 1.10" to 1.260", 1.23ish is very close to what the 1911 design was designed and built for, is a little more forgiving in the gun. Nothing at all wrong with running long loads.

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Thank you all for your help, and my edification.

I talked to Beven Grams, and we determined that I did have a 40cal mag, and that it is just too narrow. I have emailed Chris at STI, and will work it out with them.

Thanks.

Mark

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