6.5 Grendel feeding issues ASC mags

[Fox84]

Every ASC mag 10 or 20 fails to feed if you load over 4 rds. The round loads short of battery and the bolt stops clear of rd. Drop mag, pull sticking charging handle back and tilt rifle upwards and rd comes out of chamber and falls out of magwell.

Only happens on over 4 rds in mag. When you drop the mag the bolt don't close. Whats the bolt hanging up on? 5 diferant mags factory or reload.

Bolt hold open lever maybe?

 

[stagpanther]

Any damage to the cartridge--like damaged meplat, gouges, scrapes etc? Does it happen with any cartridge--in other words no matter what type of round?

 

[Fox84]

123 Amax and 107 Smk. Cases have no marks

 

[MagnumWill]

First question... does a different style of mag not induce the same failure? I found out a bunch of HERA mags I bought were junk because they managed to double-feed my PWS upper, which has never done anything other than be perfect. I probably had $100 worth of them, and they went in the garbage.

 

[stagpanther]

123 Amax and 107 Smk. Cases have no marks

Factory ammo or reloads? Any deformation of any kind on the bullets themselves, especially deformation at the tip--or a concentric "ring line" around the circumference of the bullet? Did you measure COL before and after cycling and are they the same? a high percentage of the time I've had a sticky cartridge inside a grendel type chamber it's because the bullet chambered in such a way (my theory is that they get knocked slightly out of concentricity when glancing off the chamber face on feeding) that it jammed the bullet in the chamber's throat. If all of that is perfectly normal--then I would guess your issue lies elsewhere than the magazines. Also, I usually grind feed ramps into my upper that resemble picture two to help feeding (if your upper does not already have them).



Of all the AR builds in different calibers that I've done--grendel and it's progeny are by far the most finicky when it comes to cycling.

 

[tahunua001]

never had feed problems on my grendel but it sounds like feed lips are out of alignment and it's only enough to cause issues if spring tension in the mag is stiff enough to force the mag to sit a certain way(IE the tension caused by more than 4 rounds in a mag)

PS, I also use all ASC mags.

 

[Double Naught Spy]

Sorry I am late to the thread. This is what I found with my ASC mags that sort of matches your issue. I would have the same sort of hangup, but it was more random...

Video...
https://youtu.be/0Axr5m1Daxc

You can grind the front edge or adjust the feed lips. The video only mentions grinding because that is what I was doing at the time, but I got comments from folks that suggested opening the lips a bit.

As an aside, this is not just a Grendel issue, but one that sometimes happens in 6.8 mags as well (according to my 6.8 buddies).

 

[stagpanther]

To add to double naught--here's my old c products 6.5 mag that generally will feed anything in my grendel or 6mm predator up to about 2.280 COL. I filed the feed lips down so the sharp edge was gone, rounded the front off a bit and then used a feed lip tool to put a slight upward pitch to the cartridge.



You can see here how the cartridge is angled up better to not only clear the magazine--but also provide lift to the cartridge that it otherwise won't get because the bullet will engage the ramps before the shoulder starts getting lited by the ramps. This also helps minimize the damage to the bullet from the meplat glancing off the breech/chamber face. The cartridge in the magazine is a dummy one--you can see how the meplat of the sst has been damaged from previous tests.