Acsr Posted October 4, 2016 Share Posted October 4, 2016 Hey fairly new to open about a year or so. Had a mag question. I bought my trubor of the classifieds it came with 5 mags, 1 170 and 4 140. Gun iss 38 super/ supercomp, runs either extremely well. But I would like to know expected mag capacity especially for the 170. I can get 27 re loadable of Super or super comp, any more then that it will salt and pepper due to a round getting wedged next to the follower, below sti ribs. (Is there a easy fix to extend? ) I know they are sti tubes, not exactly sure on the springs, base pads are dawson and taran. Followers I am not quite sure, I know I have two dawson type i bought one after my first issue thinking it was the problem. and one stock sti. The others say sti/svi, on the side of them so not sure maybe others know, but I would love one or two more rounds if possible, I know capacity is one reason people run comp, but as of now, I am limited to 27 plus one on the beep. Also 140 capacity is 22 is this correct also. Thanks in advance. Link to comment Share on other sites More sharing options...
Sarge Posted October 4, 2016 Share Posted October 4, 2016 You'll get more SC in them than straight super. I run 9MAJOR in STI mags with grams guts and bolen/TTI pads and I can get 29 in one of my 170's and 28 in the others. The 28's are reloadable and will not take another round. 140's all hold 22 reloadable. If your follower is flipping it may be an old bolens? Those things flipped with ease in untuned STI mags. Link to comment Share on other sites More sharing options...
MHitchcock Posted October 4, 2016 Share Posted October 4, 2016 9mm I can get 30 (29 reloadable) in my mbx 170s, 24 (23 reloadable) in mbx 140s. (Same mags used for 38super) If it were me I'd probably sell the Sti mags as is and buy mbx's. But I'm too lazy to play build/tune a mag. Grams followers/springs and TTI or Dawson base pads is what I see most often for local shooters using Sti mags. Also I believe there are people that can extend the ribs down for you on the Sti mags, but I may be remembering another discussion incorrectly. I'm sure some very experienced open shooters will be along that can help you tune them up. Welcome to open! Link to comment Share on other sites More sharing options...
grantwoodok Posted October 4, 2016 Share Posted October 4, 2016 In my STI 170mm (Range in lengths of tube from 168mm to 172mm) with Dawson base pad and TTI springs and followers I get 29 38SC. In my 140mm (Range in lengths of tube from 139mm to 141mm) also with TTI springs and followers I get 23 38SC. Link to comment Share on other sites More sharing options...
Acsr Posted October 4, 2016 Author Share Posted October 4, 2016 Thanks sarge for the input, but on that note I have loaded both super and comp and anything past 27 the round wedges against the follower and side of mag. Link to comment Share on other sites More sharing options...
Acsr Posted October 4, 2016 Author Share Posted October 4, 2016 Keep em coming if someone knows how to easily extend the rib that would be awesome Link to comment Share on other sites More sharing options...
grantwoodok Posted October 4, 2016 Share Posted October 4, 2016 I have never had to extend the rib or anything like that. I did use the Dawson mag tuning kit to get them all to spec. Using STI springs and followers don't get you to max capacity so my recommendation would be replace the guts with TTI and have someone tune your mags. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted October 4, 2016 Share Posted October 4, 2016 When I bought my TruBor ten years ago, I bought a matched set of 1-170 and 3-140 mags, custom fitted and numbered from Dawson Precision. The 170 "salt & peppered" from the beginning - sent it back twice, and finally told him to keep it. I now have three 170's that all work properly. If it "salt & peppers" at 27 rounds - I'd buy another 170 ... Good luck with it Link to comment Share on other sites More sharing options...
MHitchcock Posted October 4, 2016 Share Posted October 4, 2016 Not sure how well these work, but a quick google search turned these up- http://www.arredondoaccessories.com/category.cfm?cid=1001&PID=fc25l4900rdqps&GID=INS Link to comment Share on other sites More sharing options...
cecil Posted October 4, 2016 Share Posted October 4, 2016 I shoot a 9mm STI DVC... my STI 170 mags will hold 28 with grams followers & springs & Dawson +1 base pads.... I bought 2 - MBX 170 mags hoping I could get 29 in them ... without any luck... how ever I do like the idea that the MBX mags do not require a spacer... Link to comment Share on other sites More sharing options...
grantwoodok Posted October 4, 2016 Share Posted October 4, 2016 2 minutes ago, MHitchcock said: Not sure how well these work, but a quick google search turned these up- http://www.arredondoaccessories.com/category.cfm?cid=1001&PID=fc25l4900rdqps&GID=INS They won't work reliably with anything other than the factory base pad. Link to comment Share on other sites More sharing options...
MHitchcock Posted October 4, 2016 Share Posted October 4, 2016 17 minutes ago, cecil said: I shoot a 9mm STI DVC... my STI 170 mags will hold 28 with grams followers & springs & Dawson +1 base pads.... I bought 2 - MBX 170 mags hoping I could get 29 in them ... without any luck... how ever I do like the idea that the MBX mags do not require a spacer... Hmm. Myself and 3 other local open shooters can fit 29 reloadable in mbx 170s. Maybe luck of the draw? Link to comment Share on other sites More sharing options...
gerritm Posted October 4, 2016 Share Posted October 4, 2016 I use the 170mm STI & MBX mags and load 38 super. I can squeeze 28 in the STI with Grams springs and follower with Dawson basepads. Usually download 1 to 27 because the rims seem to lock when the are really tight and nose dive. I can get 28 comfortably in the MBX with their non lock back follower. Adrian from MBX said to try loading rounds a little shorter which seems to help @ 1.22-1.23 with the rim lock on 38 super. Super comp is the same amount but feed smoother. gerritm Link to comment Share on other sites More sharing options...
grantwoodok Posted October 4, 2016 Share Posted October 4, 2016 16 minutes ago, MHitchcock said: Hmm. Myself and 3 other local open shooters can fit 29 reloadable in mbx 170s. Maybe luck of the draw? With TTI spring and follower I get 30 38 SC in my MBX and reloadanle at 29. Link to comment Share on other sites More sharing options...
Glk21C Posted October 4, 2016 Share Posted October 4, 2016 You have several options: 1. If you are mechanically inclined and like to tinker you can fix the tubes yourself to get max capacity (29 rounds of SC) the bottom of the control ribs can be "extended" if you have the equipment or you can smooth them out with a dremel, sanding, and polishing. Idea is to lessen the severity of the transition of the bottom of the tube where the sides are flat to where the control ribs start to come out. You would also want to check the internal width of the tube between the control ribs. The ideal width between the control ribs is 0.740” for typ. Reloaded ammo, no narrower than 0.730”, no wider than 0.765” and keep tube square. Too narrow left to right and there is less capacity. Too wide left to right and the rounds can start to stack incorrectly and bind on each other Grams and TTI base pads will get you the most capacity as the bottom of those pads are beveled slightly inside. Dawson BP's are not beveled at the bottom inside. Personally, I think Grams BP's are the best. Grams and TTI spring and followers will work the best for capacity (again, I prefer Grams) If reloading your SC rounds should not be any longer than 1.235" OAL (+/- .005"), standard 38 super at 1.225" OAL (+/- .005") 2. If you don't tinker than go buy the MBX magazines. If you don't get at least 29 rounds of SC in them contact Adrian and he will walk you through why you may not be getting that. 30 rounds of SC is possible I hear with SC in the MBX mags, seems more common with 9mm though. good luck Link to comment Share on other sites More sharing options...
HeathForbis Posted October 4, 2016 Share Posted October 4, 2016 I get 28 in my STI mags with the Dawson base pads but it's a very tight fit so I usually only put in 27. Link to comment Share on other sites More sharing options...
Acsr Posted October 5, 2016 Author Share Posted October 5, 2016 Tried a friends set of guts that were grams follower and springs with a dawson base pad, was able to get 30 in. Both of my springs are a13 coil but shorter in oal then his, so I will invest in a set of those and be good. Thanks guys for all the input. Link to comment Share on other sites More sharing options...
alucardus Posted October 6, 2016 Share Posted October 6, 2016 I get 30 9mm rounds (29 re-loadable) in my MBX 170's with taran pads, springs and followers. Link to comment Share on other sites More sharing options...
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