Gmckinney626 Posted April 2, 2016 Share Posted April 2, 2016 So, I just finished a build on an STI Nowlin ramped frame with STI USPSA 40 slide. Ran a match last night (or tried to). Nosedive after nosedive. I'm running long at 1.200". A guy said "use Wilson .45 mags and the problem will go away". Well, lo and behold, I had 6 Wilson 45 mags in my bag. Still nosediving. He said "try these". He broke out 3 WC 45 mags. Same as mine. Gun ran the last 2 stages without flaw. So, today, I sit down with my 45 mags, scour the net, scour the usual forums, etc. I am about ready to throw a $1300 investment into Tampa Bay. He suggested cutting 1 coil off the mag springs, which he does. Did that. Still same, maybe worse. Looking for suggestions. Link to comment Share on other sites More sharing options...
Yeti Posted April 2, 2016 Share Posted April 2, 2016 Adjust & polish the feed lips to .380 - .385 at the font of the mag and .375 - .380 at the rear. This will allow the rounds to exit the mag in a smooth upward manner. Link to comment Share on other sites More sharing options...
blue edge Posted April 2, 2016 Share Posted April 2, 2016 Try shorter ammo maybe factory ammo first Link to comment Share on other sites More sharing options...
JWard79 Posted April 2, 2016 Share Posted April 2, 2016 I run an egw high mag catch on my 40 SS to bring the round a little closer to the chamber with wilson and Tripp 10mm magazines. When fully loaded the wilson magazines hold the round nose high, and the Tripp's are either neutral or nose low. It may be worth looking at the clearance between the slide stop and loaded magazine. Different bullet profiles, magazine profiles, and spring strength can affect the slide stop clearance. I had a slide stop that would occasionally contact the top round resulting in a nosedive, but it only occurred with a full Tripp mag on a slide lock reload (no issue with wilson). After fitting a new slide stop this issue has gone away. Link to comment Share on other sites More sharing options...
Gmckinney626 Posted April 2, 2016 Author Share Posted April 2, 2016 No short (factory length) ammo in STI 1911s. I bent the front of the feed lips out and it seems to cycle rapidly by hand. I guess I'll try it tomorrow at a match. Will post up tomorrow. Thanks Link to comment Share on other sites More sharing options...
ParaGunner Posted April 2, 2016 Share Posted April 2, 2016 High mag catch and tune mag feed lips to .388 wide +/- .003. Link to comment Share on other sites More sharing options...
fishsticks Posted April 3, 2016 Share Posted April 3, 2016 Atlas Gunworks has a number of videos on YouTube about tuning magazines and fixing feeding problems. While they are directed more at the 2011 platform I would think that the information on feeding angles and magazine feed lip set-up would be useful. Fortunately for me when I had this issue merely loading longer (1.2") and using Tripp Cobra 10 mm magazines cured the problem. I will say that bullet profile is also a factor. Berry's makes a round shoulder 180 gr that worked the best in my case. Any of the flat points I tried jammed. Link to comment Share on other sites More sharing options...
CHARLES D Posted April 3, 2016 Share Posted April 3, 2016 My Trojan did the same as 'fish stick'. Flat nose bullets nosed dived. Switched over to Berry's rounded shoulder and solved the problem. Link to comment Share on other sites More sharing options...
mach1soldier Posted April 3, 2016 Share Posted April 3, 2016 What's the feed ramp angle? I always recut mine to 30 degrees and feeding becomes smooth as butter. A raised EGW mag catch is very helpful as well. A normal (not raised) SVI mag catch is also raised quite a bit and helps. Round nose bullets do feed better. What recoil spring weight are you using? I have tried nearly 12 different kinds of mags in my two .40's. I found the mags didn't seem to make any difference. Link to comment Share on other sites More sharing options...
cbrconst Posted April 3, 2016 Share Posted April 3, 2016 I run an egw high mag catch on my 40 SS to bring the round a little closer to the chamber with wilson and Tripp 10mm magazines. When fully loaded the wilson magazines hold the round nose high, and the Tripp's are either neutral or nose low. It may be worth looking at the clearance between the slide stop and loaded magazine. Different bullet profiles, magazine profiles, and spring strength can affect the slide stop clearance. I had a slide stop that would occasionally contact the top round resulting in a nosedive, but it only occurred with a full Tripp mag on a slide lock reload (no issue with wilson). After fitting a new slide stop this issue has gone away. This... High mag catch and tune mag feed lips to .388 wide +/- .003. and this. Solved my same problem. Link to comment Share on other sites More sharing options...
andrewtac Posted April 3, 2016 Share Posted April 3, 2016 I used a higher mag catch, profiled the slide stop (it was hitting) and trimmed the ramp a little (it overhung into the magwell). I did some ramp polishing as well, not sure it helped. When the gun gets really dirty and I stuff 10 rounds in it STI happens occasionally, but rare. Link to comment Share on other sites More sharing options...
dons Posted April 3, 2016 Share Posted April 3, 2016 Someone already asked what weight recoil spring you are using. Sometimes the recoil spring is too heavy and will begin to strip the round from the magazine before the magazine spring has a chance to fully lift the round into feeding position. I've seen this happen in many 1911/2011s, reducing the recoil spring weight has solved the nosedive problem in most of the cases. YMMV. Link to comment Share on other sites More sharing options...
andrewtac Posted April 3, 2016 Share Posted April 3, 2016 Recoil spring too, forgot. I think I ended up with a 12 or 13 progressive. Link to comment Share on other sites More sharing options...
Scrmblr Posted April 3, 2016 Share Posted April 3, 2016 I run an egw high mag catch on my 40 SS to bring the round a little closer to the chamber with wilson and Tripp 10mm magazines. When fully loaded the wilson magazines hold the round nose high, and the Tripp's are either neutral or nose low. It may be worth looking at the clearance between the slide stop and loaded magazine. Different bullet profiles, magazine profiles, and spring strength can affect the slide stop clearance. I had a slide stop that would occasionally contact the top round resulting in a nosedive, but it only occurred with a full Tripp mag on a slide lock reload (no issue with wilson). After fitting a new slide stop this issue has gone away. I do the same (EGW higher mag catch). Positioning the mag, and round a little higher makes the angles better enough to keep the nose dives from happening. Link to comment Share on other sites More sharing options...
zipper046 Posted April 3, 2016 Share Posted April 3, 2016 I had this EXACT same problem with my Springer Loaded 1911 in .40s&w, but didn't know about the high mag catch you can buy. I actually had a spare Wilson .45acp Bulletproof SLIDE STOP I installed and the nosedive problems went away. (I also polished the feed ramp). try the high mag catch...or if you have a spare .45acp slide stop, try that. Z- Link to comment Share on other sites More sharing options...
Aircooled6racer Posted April 3, 2016 Share Posted April 3, 2016 (edited) Hello: Tune one mag to 0.395" feed lips front to back. See if will cycle by hand with dummy rounds. Test with live ammo and see how it does. Then tune the rest. I load to 1.180" OAL. Try this first before getting a higher mag release. I forgot to add this is for 45acp mags. Thanks, Eric Edited April 3, 2016 by Aircooled6racer Link to comment Share on other sites More sharing options...
Gmckinney626 Posted April 4, 2016 Author Share Posted April 4, 2016 Well, shot a match today after widening the front of the lips. It did better, but I still had quite a few dives. I've got a high catch ordered. Can anyone offer a reason why Tripp 10mm mags will make a difference? I hate to drop $200 more on mags. Is there an overshadowing difference in the tubes, or is it just the springs and followers? Was thinking about trying the flex followers first, although I have no idea if that provides more support in the front of the mag to prevent the dive. As for recoil spring, I'm running 13lb. Feed ramp is highly polished at whatever angle STI manufactures. Ramp on the barrel is set back .020" from top of the frame ramp. It's diving below the barrel ramp. I did run truncated cone CMJ 165gr bullets so far. I'm going to load up and try some RNFP to see if that helps. The slide stop is not making contact, so I haven't felt inclined to try any changes there. What about cutting some coils off mag springs to lower upward pressure? It just seems that the problem was primarily the first 2 rounds out of the mag. Link to comment Share on other sites More sharing options...
andrewtac Posted April 4, 2016 Share Posted April 4, 2016 I run bayou 200 RN. Might try them. Also there is a post on here on how to determine best OAL for your gun. Something about marking the ramp area with sharpie, run several rounds at a given OAL. Then add a little to the OAL repeat with fresh sharpie. The OAL with the least wear on the sharpie is best. I think I was 1.19 ish Link to comment Share on other sites More sharing options...
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