After switching the top-end of my Open Gun to 9mm Major, one of the problems I’ve been having is magazines. I only have three 170mm magazines and one of them is a SPS version which although reliable with 38 super, is not with 9mm major because of the overall length (OAL) and the rim in the case. The most reliable magazines are the STI and SV magazines. With the STI, you need an additional “spacer” to make the magazines work with 9mm Major. For SV, you don’t need to because of the construction of the magazine tube.
I chose to go with all SVs so I don’t have to mess with adding spacers. I found a seller online who still had the old style SV magazine tubes and got them for $150. yes, $150 just for the tube!!
Nice and shiny.
The best combination for maximum number of rounds is the SV tube, Grams 13 coil spring + Follower and the Bolens 3mm basepad. Ordered those parts from Shooters Connection for another $60.
$210 for ONE magazine. Yes, shooting USPSA Open Division is bloody expensive!!!
I mentioned earlier that I’ve only manage to fit 28 rounds into my SV Magazine tubes, but after compressing the springs for a few days, they now fit 29, as described by a few shooters on the BENOS forum.
here are the details :
- 29 in SV 170mm + Grams guts + Bolens Basepad (x2)
- 28 in SPS 170mm + STI guts + Bolens 4mm Basepad
- 22 in STI 140mm + STI guts + Bolens 7mm Basepad
Now it’s time to stop playing with the equipment and start shooting!!
I bought three used magazines from a fellow shooter on Brian Enos Forum. One SV 170mm Mag tube, one SPS 170mm magazine and a STI 140mm Magazine. I also ordered three Bolen base pads from Shooters Connection and a EGW Magazine Gauge to make sure my magazines are under the maximum length limit for the USPSA Open Division.
Two 3mm and one 7mm for the 140mm STI Magtube.
The SV Tube that I bought came with a Dawson SNL +1 base pad which does not fit the gauge, so I had to swap it with a 3mm Bolen Basepad. (One down)
the SPS magazine was really short, compared to the SV tube, so even with a 4mm Bolen Basepad, it still is under the maximum length. (That’s two legal)
The third one was my old SV 170mm magazine that came with the gun, it about a 1/1000th of an inch longer so I had to file down on some areas to make it shorter a little. I had to do the same with the black SV mag tube above. so after fiddling around a little, here are the results. I manage to make 28rounds fit, but can’t get anymore. Some folks on the forums can fit 30, I have no idea how that’s done. Perhaps I need to tune the springs or something.
The last bit was the STI 140mm mag tube. It came with an STI basepad, I tried fitting on the Dawson SNL+1 basepad and all I got was 21rounds. After replacing it with a Bolen 7mm basepad, now I get 22 out of that magazine.
here’s all of them in a row and the current ammo capacity, I tried but I couldn’t get more than 28rounds to fit reliably.
There, I’m ready to go. armed with 108 rounds of .38 Super Comp. Now all I need is my rig.
I bought two used Bolen basepads from someone on BrianEnos’ forum recently, thinking that it would fit on my 170mm and be legal (fit in a magazine gauge). After showing it to John from JPL Precision, he checked with his USPSA Mag gauge and it didn’t fit! It was just very so slightly longer.
Coming home, I checked both basepads and lo-and behold, they’re not the same! All this while I thought they were the same basepads. One was just a hair taller.
Reading up online, Bolen has three types of basepads, 3mm, 4mm and 7mm. so I guess the one on the right is 3mm and left is 4mm. What a n00b I am.
Anyway, installed the 3mm on my 170mm mag tube now, and I’m sure it’ll be legal now. Here’s how they recommend we use it in an Open Gun.
- 3mm for 170mm mag tube should yield 28-29rnds of 38 SuperComp
- 4mm for a “tuned” 170mm mag tube should yield 29-30 of 38 SuperComp
- 7mm for a 140mm mag tube for 22-23 of 38 SuperComp