Converting STI 38 Super Mags to 9mm Major Mags

[Saffer]

Does converting 38 Super STI magazines to 9mm Major magazines just entail adding a spacer? If so, are you not also required to change the follower and spring to a set that have a narrower breadth, to allow for the spacer?

If all of the above are true, would changing the internals on tuned magazines affect the maximum loading capacity with the new caliber? In other words, after the conversion will the magazines still achieve maximum capacity?

Any feedback would help.

[A63111]

You are correct that when you add the spacer you will need to replace at least the follower. May change capacity, but I truly don't recall. If the mag is reliability tuned it shouldn't change reliability.

[caspian guy]

Does converting 38 Super STI magazines to 9mm Major magazines just entail adding a spacer? If so, are you not also required to change the follower and spring to a set that have a narrower breadth, to allow for the spacer?

If all of the above are true, would changing the internals on tuned magazines affect the maximum loading capacity with the new caliber? In other words, after the conversion will the magazines still achieve maximum capacity?

Any feedback would help.

Yes you probably need spacers. I like the steel "Joey Hardy" ones you can get from Shooters Connection. As you suspected that calls for a different follower. I prefer the grams fks-11 or 13 spring and follower. There are reports of old style SV mags running 9mm without spacers but I haven't tried it.

[Blurryvisions]

just a heads up, you might just try running the mags with no spacers... I have a supercomp gun and a 9mm gun 5 sti mags in 38 super from brazos and they run in the 9mm flawlessly... give it a chance before you go spend a bunch of money you might not need to spend

[TMC]

Blurryvisions is right, try them first. I have 13 mags, half STI half SV with a wide variety of springs and followers and they run 9mm fine in all 3 of my guns.

Edited December 16, 2011 by TMC

[Hi-Power Jack]

you might just try running the mags with no spacers... I have a supercomp gun and a 9mm gun 5 sti mags in 38 super from brazos and they run in the 9mm flawlessly...

One trick is to load your 9mm major a little longer

- out at least 1.145" - 1.165" is probably better

if you're not using spacers. If that doesn't work,

try going out to 1.175".

[03k64]

I load to 1.165" and I need spacers in my tuned STI mags. They just wouldn't run 100% without them but YMMV. If you do need spacers, I agree that the steel ones are better than the plastic ones.

[A63111]

I have an old style SVI mag, runs without spacers. I was told by Bevin Grams that the rib is what allows this. SVI has a large depression where STI has ribs. The SVI is able to guide the shorter 9mm cases better. I run the "Joey Hardy" spacers in the STI's. Another thing to look at is the width just in front of the ribs, it must be snug enough to guide the bullet and limit side to side movement.

[bassochist]

i also use an svi old style 160mm mag, without spacers, runs perfect in my sti, my 140mm mags have arredondo spacers, grams springs / followers, and dawson basepad, they run also without any problems.

i load my 9mm to 29.4 mm oal.

[gng4life]

Yeah, I agree with Blurry, try it out first to see if there are any problems. I use almost all SV and I don't use spacers and I don't have problems. I purchased an STI mag to be on my practice/drop mag and I immediately put a spacer in it since I was told that I had to. Later, I talked to the guy I purchased it from and he said he never had a spacer in there and used it in 9Major many, many times - no issues. There was a long thread on here a while back talking about that. It seemed from the consensus that if you load to 1.165 or longer, you should be okay without a spacer. Although some reported having problems even with a longer OAL, most didn't.

Like it was said, try it first in practice - not in a match, to see how things go. Then you can decide if you need the spacers after that...

Also, I believe the dimensions for the feed lips are slightly larger for 38 Super but it should be close enough to work fine. If you start having feeding problems, this is one area to look at also...

[Saffer]

Thanks for the feedback. I currently load to 1.171 and use STI mags with spacers, only because I was told it was more reliable. I have not tried the magazines without spacers since they have been flawless ... well at least since I tuned the feed lips.

My currentl question revolves around converting mags, since I am looking at buying additional mags that are currently set up as 38 Supers. Tuning the lips is straightforward, and I use the Dawson kit for that. I think my approach would be to check the feed lips, then to test them in their current configuration. If they work, great. Otherwise insert spacers and swop out the followers. I think the springs may be okay, and won't rub against the spacers, but I may be wrong.