Hey guys, new to the 6BR world and mag tuning. I’m running an Impact, TCS, prefit 6BR barrel, MDT 12rd BR mags, and factory Lapua ammo. New out of the box, the bullet tip is hitting the barrel just below the bore. I try and tweak it and get a variety of feeding, bullet tip too high, bullet tip too low, and/or rounds pop out early. Does anyone have feed lip measurements that work for them, or mag tuning advice in general?
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6BR mag tuning
- Thread starter mercracing
- Start date
Different action, but can't hurt to try... try the feed lips at 0.430 in the rear and 0.420 in the front.
Here is another idea if that doesn't work - strip your firing pin out of your bolt to be safe and setup your phone/camera next to the action so you can video it while you run a few rounds out of the mag and see what's happening in there - nose up, nose down, round popping up, etc. Load just 1, 3, 5, etc. You can get different effect based on the round count. Look at the back of the round and see how high it is sitting up based on the primer - lips closer = round higher, lips further apart = round lower.
Good luck - this is frustrating as hell, but once you get it note down your measurements and it is 100% transferrable to extra mags of the same type - don't buy a bunch of different brands or types. Get one that works and buy more of that and set it up the same way.
Here is another idea if that doesn't work - strip your firing pin out of your bolt to be safe and setup your phone/camera next to the action so you can video it while you run a few rounds out of the mag and see what's happening in there - nose up, nose down, round popping up, etc. Load just 1, 3, 5, etc. You can get different effect based on the round count. Look at the back of the round and see how high it is sitting up based on the primer - lips closer = round higher, lips further apart = round lower.
Good luck - this is frustrating as hell, but once you get it note down your measurements and it is 100% transferrable to extra mags of the same type - don't buy a bunch of different brands or types. Get one that works and buy more of that and set it up the same way.
No. It’s cut for aics.
You used to be able to get them in aics or aw.
Now they just do the one aw option.
Op, measure your lip widths so you can go back to a baseline and just play with it from there. My aics br mags I flared the front to work well, the guy above went tighter. Just takes trial and error in my experience. My creed I had to make tighter. Seems counter intuitive but it’s what worked so I took it.
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I’ve ran a couple 6CM barrels through this action without issue. Didn’t have to mess with those mags at all. I currently have 2 12 rounders, one I haven’t touched just so I have base measurements.
Do all 12 rounders from MDT have the new style followers?
I have a impact / 6br, suppose to be cut for aw mags. Don’t know how to tell…
MDT mags with the new followers feeding perfectly without any adjustment out of the box.
Two old 10 rounders let the rounds “nose dive” intermittently. I will get updated parts for these.
3 new aw / hrd kit mags I have will not feed at all, bolt rides mostly over and when not rounds nose dive.
Have not tried to adjust them yet.
It’s in a MDT ACC if this helps.
I have a impact / 6br, suppose to be cut for aw mags. Don’t know how to tell…
MDT mags with the new followers feeding perfectly without any adjustment out of the box.
Two old 10 rounders let the rounds “nose dive” intermittently. I will get updated parts for these.
3 new aw / hrd kit mags I have will not feed at all, bolt rides mostly over and when not rounds nose dive.
Have not tried to adjust them yet.
It’s in a MDT ACC if this helps.
I don't measure mine typically, but make small iterative tweaks to open/flare out the front part of the feed lips until they feed smoothly. Small changes can make a decent impact on how it feeds.
No big changes, just small iterative steps until you find the sweet spot.
No big changes, just small iterative steps until you find the sweet spot.
A lot of times running MDT mags you need a longer magazine latch on your bottom metal. Ask your bottom metal manufacturer for the Long or AW latch. They hold the MDT mags up higher and seem to cure most feeding issues with MDTs.
