Brent D Posted February 17, 2011 Share Posted February 17, 2011 I have been shooting my first open gun for the last few months and have about 4K rounds through it and have been troubleshooting ejection problems with the 170mm mags since day one. I cannot in this post list every detail of what has been going on, but here goes. All of my mags have grams basepad, spring and follower as well as 9mm spacers. The tubes and guts were ordered from Brownells. The 140 mags run flawlessly, but when I run the 170, 10-20% of the time I get a case that appears to hit the bottom of the cmore mount and then gets crunched in the ejection port as the slide attempts to return. I have experimented with all kinds of OAL on my reloads with no change in function. When I try to troubleshoot, I keep coming back to the same question: WHY IS THE PROBLEM ONLY WITH THE 170MM MAGS AND NOT THE 140'S? As a part of my troubleshooting, I purchased a tuned STI mag from shooters connection. This mag seems to run 100% better. How can a magazine effect extraction and ejection in 9 major? I checked the problem magazines with my calipers and the opening on the top of the mag is about .02" wider on the tuned mag that works well. I am new to this sport, as I have been shooting for about 1.5 years and this is my first open gun, but I am learning alot. Forgive me if some of my observation seems elementary. Link to comment Share on other sites More sharing options...
Singlestack Posted February 17, 2011 Share Posted February 17, 2011 The 170 you are having problems might be seating too close to the ejector. Take the top end off and compare it too the one that works. The larger mag catch hole might be letting the one that works sit a bit lower. Link to comment Share on other sites More sharing options...
BlueOvalBruin Posted February 17, 2011 Share Posted February 17, 2011 Maybe since the gap is greater and the top round in the mag sits higher, it’s pushing up on the spent casing a bit so the ejector hits lower on the case head. That in turn would cause the ejection to be angled up higher. Part of the mag tuning process is to set the feed lip gap so it sounds like your mag needs tuning. You can either send it out for tuning or buy a dawson mag tuning kit and do it yourself. Link to comment Share on other sites More sharing options...
wide45 Posted February 17, 2011 Share Posted February 17, 2011 170's are knocking the fired case off the extractor causing the fumbled ejection. Fix your weak extractor, and tune the mags to sit at the same height as the 140's. Link to comment Share on other sites More sharing options...
Aircooled6racer Posted February 17, 2011 Share Posted February 17, 2011 Hello: Set the feed lips to 0.356" on the 170mm mag. It should feed fine then. Thanks, Eric Link to comment Share on other sites More sharing options...
mra8541 Posted February 17, 2011 Share Posted February 17, 2011 I've been through a few 170's and for 9mm or 38 you feed lips need to be .355 to .356 as stated before, make sure your reloads are no longer that 1.250 as well as properly crimped. Always take your spring out after a stage and give it a little strech out and the last coil should be at about a 45* angle so it properly pushes up on the follower, causing it not to dip forward. And you will probably have to replace your 170mm spring every 3-4 months vs. your 140's about once a year. Link to comment Share on other sites More sharing options...
TRUbor9 Posted February 19, 2011 Share Posted February 19, 2011 Get the Predator Tactical side mount(http://www.predatortactical.com/Predator-C-more-Side-Mount-p377.html) and read the ejection perfection article on brazos site Link to comment Share on other sites More sharing options...
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