Mbx vs STI gen 2 mags

[Dane460]

Recently bought an mbx mag and love it but I see the STI gen 2 mag now looks similar and doesn’t run a spacer anymore either. Anyone have experience with the new gen 2 STI mags?? Tryin to decide on more mbx mags or try the gen 2s

[hump]

The STI gen 2 mags work well for me. I am using them straight out of the box. 

[jcc7x7]

STI mags are the only thing I buy that says STI on it anymore.

Their mags work fine for me. Not so much their guns imo

[RangerTrace]

Their new 126mm mags work perfectly for IDPA.  At the new price, I'm going to try some 140s for 3gun and Limited.

[zzt]

I mostly use 155 and 170 MBX mags, but I have two 9mm Gen 2 mags I use for classifiers or when I have to drop a mag in dust or mud.  They run fine, but capacity is limited.  The so called 140s I have are short.  I can cram 21 in, but only 20 reloadable.  That's fine for classifiers.  I don't know how long the plastic base pads will hold up, but otherwise they are a big improvement over the Gen 1s.  I run them just as they came out of the package.

 

If you are looking for max capacity, by the time you add an 11 coil spring, follower and extended base pad, you are so close to the price of an MBX it isn't worth it.

[Dane460]

Ya I think I’m just guna but some 140 mbx mags since I already know I won’t have issues 

[zzt]

If you would like 155s instead, Shooters Connection sells them for the same price as the 140s.    Ooops, not any more.

Edited March 26, 2019 by zzt

[Jfitz427]

Actually, going with sti gen 2s plus basepads and springs and followers is considerably cheaper then mbx mags. Mbx mags are 130 for a 140mm. Or 50 for gen 2 mag, 30 for basepad and 20 for the guts. So 100 total, 30 bucks cheaper then mbx. Over a set of 10; it’s a considerable amount of money. 

 

I really like the new sti mags a lot. Especially for 40, they just work great. But With 9 they sometimes need some tweaking. The double to single transition is a bit wide from the factory and it causes the rounds to stack wrong, and you get a big gap between the first and second round in the mag. And this causes rounds to nose dive. They come around .620-.630, and they need to be brought down to about .560-.570, one inch down the tube. It’s pretty simple to do. And after this they go from about 95% reliably, to 100%. But even then I still trust my mbx more. They have the dimensions right, and they stack up neatly and are just very reliable. So I practice with sti and shoot matches with mbx. 

[zzt]

Geez.  I paid $68 each for my Gen 2 140s.  I haven't done the Atlas squeeze on them yet, because they have been 100% reliable so far.

[Posvar]

I tried a new gen2 in my .40 edge and it wouldn’t run to save my life. All my Gen1 Sti and MBX have worked very well. 

[hamiltonian]

I just got a couple of Gen 2 STI 140mm 9mm mags to try in my open gun.  They worked perfectly out of the box - no tweaking necessary.   At $49.99 each, they are a good deal.  I am using them for steel challenge.

[Jfitz427]

5 hours ago, zzt said:

Geez.  I paid $68 each for my Gen 2 140s.  I haven't done the Atlas squeeze on them yet, because they have been 100% reliable so far.

When I bought my first 5 they were 75 bucks a piece. They’re a really good deal now at 50. I just picked up 2 for 50 a piece and theyre actually different then my first 5. The first 5 I bought said just “9mm” on them, and nothing else. These new ones say “9/38”, and in a different font. The tubes look identical though. And seem to be dimensionally the same too. So idk maybe people thought they were only for 9mm, so they started stamping 9/38 so people knew they were for both. 

[Furrly]

On 3/26/2019 at 6:48 AM, zzt said:

I mostly use 155 and 170 MBX mags, but I have two 9mm Gen 2 mags I use for classifiers or when I have to drop a mag in dust or mud.  They run fine, but capacity is limited.  The so called 140s I have are short.  I can cram 21 in, but only 20 reloadable.  That's fine for classifiers.  I don't know how long the plastic base pads will hold up, but otherwise they are a big improvement over the Gen 1s.  I run them just as they came out of the package.

 

If you are looking for max capacity, by the time you add an 11 coil spring, follower and extended base pad, you are so close to the price of an MBX it isn't worth it.

ZZT what guts are you running in your MBX mags , 140

[zzt]

1 hour ago, Furrly said:

ZZT what guts are you running in your MBX mags , 140

 MBX guts and pad.  All stock in both 40 and 9mm.  The only thing I did to the 9mm 155 mags was swap out the Gen2 follower for a Gen 1.  It works better and gives me 25 reloadable.  170 is 29 reloadable.  40 140s are 20 reloadable.  The 40 170 will accept 26, but only 25 reloadable.

[B_Seehawer]

My vote is for MBX tubes and base pads and TTI guts. Zero failures in the few years I’ve run them. I’d really like to snag a few 155’s to play with though.

[cferree]

Before selling the gun, I had 3, Gen 1 140's  and 3, Gen 2 140's (all 9mm).  Both sets ran, but the Gen 1 required a lot more tuning.  They weren't square and the feed lip dimension weren't close to Dawson's recommendations.  I had to use Dawson 9mm base pads in the Gen 1's for the SS spacers to be in the correct location (they would slip down into the base pad with TTI pads cause FTF's for the last 2-4 rounds).

 

The Gen 2's were square.  The feed lip dims were close enough that I could have run them as they came out of the packaging.  I set them to the Dawson number just to be consistent.

I used TTI followers and base pads.  They ran great. 

 

As JCC7X7 stated above, the Gen 2's are the only thing I'd buy from STI right now.  One broken slide and a four month warranty wait later, I sold the gun and mags and haven't looked back.

[Stymie12000]

Gen 2 are gtg! I like them a lot. 140 mag body with Taran Tactical thin follower and base pads. I get 24 loadable.  170 with the same setup I get 30 loadable.  Zero issues. 

 

My MBX gave me issues.  So Sti Gen 2 for me!

[Tcotter2629]

I’ve run the same 8 mbx mags for awhile but I’m considering for the price trying the sti gen 2 with TTI basepads and gram guts. 

[theblacklabel18]

Either choice is a good one, as long as your gun likes them, which most properly built guns will do fine. I’ve run MBX in the open gun without tuning nor issue, the new STI’s are also great, especially in 40. You have more options for followers and basepads with the STI’s though, as the MBX are designed to work and fit the box with MBX components. The only time I’ve seen problems with them is when people frankenbuild mags with other brand followers and basepads, and a lot of the time they don’t fit the gauge anymore. Best of luck!


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[zzt]

I ran into a problem using one of my MBX 155 mags at a match on Sat.  It started not feeding the first or second round in the mag.  I stopped using it.  When I got home I measured the feed lips.  They were .010" tighter than the other mags.  I opened them up and everything is good again.

 

I just ordered a third STI Gen 2 140.  The first two work great.  I'll use these three for Steel Challenge and save the MPX for USPSA.  I also plan to order one set of TTI base pads, spring and ultra-thin follower to see how they work. 

 

The Gen 2 mags lock the slide back with no rounds left.  The only beef I had with the Gen 2 mags is they stick in the Uplula mag loader.  I Dremeled out the bridge on one of the loaders and now it works fine.

[Jfitz427]

8 hours ago, zzt said:

I ran into a problem using one of my MBX 155 mags at a match on Sat.  It started not feeding the first or second round in the mag.  I stopped using it.  When I got home I measured the feed lips.  They were .010" tighter than the other mags.  I opened them up and everything is good again.

 

I just ordered a third STI Gen 2 140.  The first two work great.  I'll use these three for Steel Challenge and save the MPX for USPSA.  I also plan to order one set of TTI base pads, spring and ultra-thin follower to see how they work. 

 

The Gen 2 mags lock the slide back with no rounds left.  The only beef I had with the Gen 2 mags is they stick in the Uplula mag loader.  I Dremeled out the bridge on one of the loaders and now it works fine.

Both of my 170s are mbx. I figured mbx works, and it’s harder to get the 170s going so I might as well get mbx for those. And they work perfectly. But all my 140s are sti. TTI 7mm base pad with grams s&f. And at first they ran 100%. For the first 2 months or So. Then they started nose diving very infrequently. Say 3-5% of the time. But that’s still to much for me to rely on for matches.  So I’ve been thinking about getting a set of mbx 140s or 155s for matches since they work so well. And use the Stis for practice. 

 

Then i found the atlas video you told me about and squeezed them in to the right specs and now they’re 100%. I just bought 2 more when they dropped the price and I’m leaving them stock. Getting that 2-3% nose dives again. Didn’t want to mess with them but I might have to squeeze them. But after squeezing the other ones idk if I’m gonna buy any MBX now. The mbx mags just work so well. They have those tube dimensions right. No gap between the first and second round like wirh the Sti mags. Idk. The sti mags are just such a bargain at 50 a piece. 

Edited April 1, 2019 by Jfitz427

[zzt]

I didn't squeeze my Gen 2 mags and there is no space between the top and second round.

[hitman_usmc]

I have several MBX and about half of them seem to have issues when I get down to only four rounds in the magazine.  Not sure what dimension is off, but it runs great until there's four left and all the spring tension seems to go away.  After knocking the round out, the last 3 feed fine again.  I assume it has something to do withe the area where the double stack goes to single or maybe something is catching the follower at that point, but I can't seem to get it right yet.  My STI gen 2 and atlas videos have been the ticket for me.  

[zzt]

hitman, if you are running Gen 2 followers in your MBX, what you describe is probably due to that.  When I load mine, there is a pause or resistance at the 4 or 5 round level, then it goes back to normal.  Try bending the spring so the follower has a little steeper slant.  I know that's not what Atlas says, but he is wrong on that one.

 

BTW, if you are running 155s, you can cut one coil off the bottom of the spring.  It doesn't gain you any capacity, but it does reduce pressure on the feed lips and it works better.

[hitman_usmc]

Awesome, I'll give that a try.  Thanks!