03-07-2017, 12:02 AM
Originally Posted by Toban
Towards the end, I stop moving the bolt and carrier as the bullet rises at the front. Prior to cleaning up the sharp edges on the bottom of the bolt, the round would occasionally flip up at a 35 or so degree angle, yet it was still caught by the base between the feedlip and the next round (or the follower) beside it. When the bolt came forward, it would catch the corner of the casing and smash it upwards into the chamber. A specific dent would then be visible where the feed ramp impacted the side of the case, and depending on how far the cartridge was actually driven into the chamber (how bad the angle up was), the bullet may or may not be rammed into the case.
If this doesn't quite make sense, compare your bolt to mine and you'll see a squared off spot instead of a slope where mine has been filed down. It's that notch that catches the extractor groove of the next shell.
I staged this picture in an effort to explain what the retraction of the bolt causes. The dent on this casing is the dent I describe earlier, caused by the bolt attempting to chamber the cartridge at an extreme angle.
Last edited by Toban; 03-07-2017 at 12:08 AM.
The Following 2 Users Like This Post By Toban
ESnel (03-07-2017), harbl_the_cat (03-07-2017)
03-07-2017, 08:18 PM
I wonder if that is why I had two rounds out of the last 300 get mashed into the feed ramp to the point that the set bullet was pressed another 3-4mm into the casing. I'll check mine next time I'm out.
03-07-2017, 08:46 PM
Wait until you drive 'em so far in the powder spills out everywhere. This especially sucks if it's raining.
Originally Posted by shootemup604
I'd be curious to see pictures of where harbl_the_cat has adjusted his T97s. I really haven't screwed with my feedramp yet.
03-07-2017, 09:08 PM
This would exacerbate the issue I described with the bolt. If you push up on the mag past where it should seat, the top round is even more likely to get caught on the bolt when it cycles.
Originally Posted by harbl_the_cat
03-19-2017, 12:12 AM
I haven't had a chance to look at my T97's, but Toban, I think you are really onto something with this discovery.
In particular, I have had intermittent problems with steel beowulf mags through my T97 with the misaligned bullet setback FTF you identified.
I think it would make sense, since mag lips are much shorter on the beowulf mags than they are on normal LAR or AR-15 mags.
Definitely something I'm going to test next time I'm able to check out my guns.
03-20-2017, 08:43 PM
Can you post some extra pictures and maybe a video of your bolt, Toban?
03-21-2017, 05:27 PM
Originally Posted by Toban
Carve out that notch in the back of the mag more.
Make it square.
These are not made for the polymer mags but if you look at the stock ar metal ones you will know what I mean.