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 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