gunner40sw Posted October 31, 2022 Share Posted October 31, 2022 I have a drawer full of STI mags and I need to determine if they are 9mm or 40S&W. I have gone through them and separated the ones that will not fit a 40 in but I also have probably a dozen that ill have a 40 fit along with a 9mm. maybe because they have been dropped and the feed lips got bent. So is there anywhere I can find a drawing with the measurements at the different points on the magazine. And that brings me to my next question has anyone ever ordered the mag tuning kit from Dawson and if so how hard was it to do and do they work. Link to comment Share on other sites More sharing options...
vtecpaoche Posted October 31, 2022 Share Posted October 31, 2022 I'm not sure if I've seen one with the formal dimensions for each mag. The closest I've seen to actual specs are from the Atlas Gunworks videos but I'm not sure they are official. I'm sure STI had a range that was acceptable but Atlas seems to share the stats that best work for them. There's a bunch of videos from them but I'll link two that may help you. As for the Dawson guide, they are pretty useful. I think the tool to bend the feed lips back out can be gotten elsewhere but the block to support the magazine when you are hammering is unique. You may be able to buy one used as I've seen quite a few listed in the for sale section in the past. Link to comment Share on other sites More sharing options...
Grendel Posted October 31, 2022 Share Posted October 31, 2022 If they are 1 generation STI mags, there are deep indents /ribs om both sides of the 9mm magazines, 40 have one shallow side/one deep side. Link to comment Share on other sites More sharing options...
gunner40sw Posted October 31, 2022 Author Share Posted October 31, 2022 I will check out the videos thanks for those and I will check the mags for indents/ribs. Also I just came across these in my drawer they have never been used and I think they are SVI 170mm in 40 S&W. Does anyone even use these anymore I was thinks of selling them Link to comment Share on other sites More sharing options...
gunner40sw Posted October 31, 2022 Author Share Posted October 31, 2022 Link to comment Share on other sites More sharing options...
davsco Posted October 31, 2022 Share Posted October 31, 2022 gen 1 sti 9mm mags should have the thin plastic spacers in them that run along the backside of the mag. Link to comment Share on other sites More sharing options...
gunner40sw Posted October 31, 2022 Author Share Posted October 31, 2022 isn't there a spring and follower that you can run so you don't have to use the spacer Link to comment Share on other sites More sharing options...
Don_B Posted October 31, 2022 Share Posted October 31, 2022 I put a post on your for sale ad. I feel fairly certain that the right mag is 38/9 by looking at the side panel. Hard to tell on the left one. Link to comment Share on other sites More sharing options...
Don_B Posted October 31, 2022 Share Posted October 31, 2022 If you have calipers measure the width of the feedlips. 40 mag should be .370-.380 38/9 mags should be .330-.350. These are approximate measurements but close enough for you to tell the difference. Link to comment Share on other sites More sharing options...
davsco Posted October 31, 2022 Share Posted October 31, 2022 2 hours ago, gunner40sw said: isn't there a spring and follower that you can run so you don't have to use the spacer i'm not aware of that option but that doesn't mean there isn't one. on some of my 9mm gen 1, i replaced internals with grams spring and follower but still use the spacer. Link to comment Share on other sites More sharing options...
Brazos Custom Posted October 31, 2022 Share Posted October 31, 2022 Those are not STI mags. STI gen 1 mags have 2 ribs running down them on each side. 38 has deep ribs on both sides. 40 has deep ribs on one side and shallow on the other. The mags shown look like they might be older SV mags. Link to comment Share on other sites More sharing options...
echotango Posted October 31, 2022 Share Posted October 31, 2022 2 hours ago, gunner40sw said: isn't there a spring and follower that you can run so you don't have to use the spacer Yes, you just need to get the grams 38 follower. Link to comment Share on other sites More sharing options...
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