STI Mags

[bthunter019]

Ok so I got some answers about the follower rolling over in my big stick after putting the 28th round in. 2 questions, first has anyone tried and had success with the inserts from arradondo that extends the ribs down the side of the STI mags that help stop the roll over of the followers and #2 does anyone know if there is anyeay to extend the ribs down the side of the mag. Had a shooter tell me to take a punch and and hemmer it down the lines where the ribs stop to extend them. Also had a suggestion of just buying a SVI mag tube, putting in my own guts and away I go. That is the easy way, I wanna try and get this one to run all the time before I give up and have to go out and buy a new tube. By the way the tube runs great with 27 plus 1 in the pipe. I can get 29 in there with 1 in the pipe but at 28 when it reaches the end of the ribs it rolls over and becomes a salt shaker.

[trodrig]

I have 2 STI 170mm mags that will hold a reloadable 28 rounds without the Arredondo spacer. You really shouldn't need it for 28 rounds. Has the tube been tuned at all? I would be reluctant to try and hammer on it with a punch to try and extend the ribs. I thought about this once before but I think it would be difficult to make it very smooth and I wonder if the follower would still get hung up if the transition is not smooth. Also, as you're hammering, you may compress the tube if it's not supported from the inside. SVI tubes are not necessarily 'easy' either. The new style tubes are different and require some work to get them to run in an STI frame, assuming you are using an STI frame here. You can search the forum and find some information on what's required and difficult people have had with them. Not to say they can't be made to work...just require some effort.

Sorry, I don't know the history but, for the STI tube you've got, are you using Gramms spring/follower and Dawson basepad? That's the setup I have in both of mine and they hold 28 rounds.

[40S&W]

Change your springs & followers over to Grams; they don't rollover. My STI 170mm 9mm tubes with Dawson SNL bases and Grams springs & followers, & SS spacer hold 29 reloadable or 29+1 to start. My STI 170mm 38SC tubes with Dawson SNL bases and Grams springs & followers hold 28 reloadable or to start 29+1. No rollover problems whatsoever for either caliber. Mags were not tuned.

[G-ManBart]

Change your springs & followers over to Grams; they don't rollover. My STI 170mm 9mm tubes with Dawson SNL bases and Grams springs & followers, & SS spacer hold 29 reloadable or 29+1 to start. My STI 170mm 38SC tubes with Dawson SNL bases and Grams springs & followers hold 28 reloadable or to start 29+1. No rollover problems whatsoever for either caliber. Mags were not tuned.

That's not really true. I've found a number of combinations with Grams springs and followers where they'd roll in an STI tube. It depends on the exact tube, since they're all slightly different. Take your example above, you should be getting more rounds of 38SC in your mags than with 9mm, because 9mm cases have a larger head diameter. In most cases, you get a full round extra going from 9mm to 38SC in a big stick, but that isn't how it worked out with your tubes, for whatever reason.

In fact, I found that an STI 140mm tube with an 11mm Grams basepad, and Grams 13-coil spring and follower would roll over with 23+rds in it. So, I added the Arredondo basepad insert, and they ran 100%. I eventually switched over to mostly SV tubes, but I do have some 140mm STI tubes running Grams springs/followers, and Dawson standard basepads that are 100% reliable, hold 22 with nearly enough room to get a 23rd round in, so the springs seem to last forever (still replace them yearly). I use them mostly for training, but they're handy for classifiers, or short stages, and let me minimize wear/tear on my higher capacity, tuned mags.

With big stick STI tubes, anything over 28rds is sort of on an individual basis as for what will work. I've found the same to be true for SV tubes over 29rds...just depends on the tube (unless you're good at tuning them). R,

[hunt_fish]

Any tips on how to properly tune the internals of the mag?