Need some help from the AR guys: 6.5 Grendel misfeeds

Status
Not open for further replies.
Legionnaire

Legionnaire

Contributing Member
Joined
Dec 24, 2002
Messages
8,638
Location
Texas
Need a little help. Here's the situation. I have a 6.5 Grendel that I assembled from a PSA lower and a PSA upper bought at different times. The upper has an 18-inch barrel with a rifle-length gas tube. Here's the problem. I have a couple of 10-round ASC magazines. Whether I load them up with 10 rounds, 5 rounds, or even 2 rounds, the second to last round misfeeds. It jams and the shoulder gets crushed in two places, no doubt from the bolt lugs. Looks like this. The dents get ironed out on subsequent firing.

HowaDay1-04.jpg

Weird thing is that it only happens on the next to last round in the magazine. If I took the round pictured above and put it back into the mag on top of one other cartridge, it would jam again. If I put it in on top of two rounds, it would feed fine, and the round immediately following would jam. I'm guessing this is a magazine problem, but I'm not enough of an AR guy to know how to troubleshoot it. Any suggestions?

I do have a few Elander mags I haven't tried yet; I'll take them along next outing.
 
Can we see a phot of the barrel from the chamber end showing the feed ramps please. I would also like to know where those dents are in relation to the barrel lugs and bolt lugs.

While I have zero experience with 6.5 Grendal, I do have AR's in 6.8 SPC and 6mm ARC. And all I use for both is ASC magazines.I have not had any issues with the 6.8 or 6 ARC magazines from ASC.
 
Legionnaire said:
It jams and the shoulder gets crushed in two places, no doubt from the bolt lugs.
Click to expand...
No. You would need to disassemble the gun to touch the cartridge shoulder to the bolt lugs. It's being crushed against the locking lugs in the barrel extension.

When it occurs, look at the jam before clearing it. I believe you will observe a three-point jam: bullet nose up into the chamber or extension, cartridge base too low in the magazine, shoulder jammed down against the lugs adjacent to the feed ramps. This suggests magazine lip geometry (including height) or spring tension as the issue.

Experiment forthwith.
 
@edwardware, that sounds right. Your description of the three-point jam is what I recall it looked like, and if you look closely at the picture, you can see slight deformation of the plastic tip, indicating it got hung up on something. I'll do some experimenting next time out. I'll also take the Elander mags and try them.
 
Those aren't bolt lug marks, they're feed ramp marks.

Don't let these guys talk you into buying a bunch of different magazines. My properly built Grendel won't feed reliably either and I've tried four different brands of magazines.

It will never feed 100%, in my experience and you'll just have to live with that aspect of the cartridge in that platform.

After building mine, I figured it was probably designed to sell a bunch of different mags for someone.
 
Factory ammo ? or reloads ? .. if reloads your OAL "might" be a little to long for reliable feeding ?

And is the bullet crooked in the pic ?
And Yes, the fubared spots are from the barrels lugs.

I have seen mags cause feeding issues like yours. I would try a different brand magazine first.
 
For me, ASC mags have been hit or miss. The fact that you have two and neither works is a bummer. I'll echo what others have said. Try a Duramag. I've seen similar problems with ASC mags in 9mm, 7.62x39, the Grendel and others.

HKGuns said:
Those aren't bolt lug marks, they're feed ramp marks.

Don't let these guys talk you into buying a bunch of different magazines. My properly built Grendel won't feed reliably either and I've tried four different brands of magazines.

It will never feed 100%, in my experience and you'll just have to live with that aspect of the cartridge in that platform.

After building mine, I figured it was probably designed to sell a bunch of different mags for someone.
Click to expand...
I don't know man. If it won't run right with any magazine, I don't think it's a mag problem. Did you use an Anderson lower? In any case, maybe try swapping your mag catch for another, preferably milspec from a good manufacturer, especially if you're running an Anderson. With tolerance stacking and all, it doesn't take much to muck things up.
 
TonyAngel said:
For me, ASC mags have been hit or miss. The fact that you have two and neither works is a bummer. I'll echo what others have said. Try a Duramag. I've seen similar problems with ASC mags in 9mm, 7.62x39, the Grendel and others.


I don't know man. If it won't run right with any magazine, I don't think it's a mag problem. Did you use an Anderson lower? In any case, maybe try swapping your mag catch for another, preferably milspec from a good manufacturer, especially if you're running an Anderson. With tolerance stacking and all, it doesn't take much to muck things up.
Click to expand...
It is built on Wilson Combat components and a Colt LPK with VLTOR rear end. Some mags work better than others, but they all fail to feed reliably enough to trust.

I've built a lot of AR Rifles, many 556 variants and also 450BM - 458 SOCOM - 6.5C all function flawlessly, the Grendel, not so much. Personally, I'm convinced those short fat cartridges will never feed reliably.
p2841517635-5.jpg

p2841517852-5.jpg


Sorry for the thread-jack OP, just answering a question.
 
Last edited:
OP, something else to consider, it may not be your mags, it may be your bolt.

One of the other things I tried was to buy a bolt from Alexander Arms. It made a difference but still not 100% in my case.
 
Status
Not open for further replies.

Similar threads

C
  • Locked
Remington 7400 30-06 misfeed problems
Replies
24
Views
18K
d2wing
d2wing
E
  • Locked
Will the 6.5 Grendel work in my FAB-10 lower?
Replies
2
Views
600
El Rojo
E
geim druth
  • Locked
Remington misfeeds
Replies
4
Views
383
geim druth
geim druth
J
  • Locked
6.5 Grendel AR question
Replies
11
Views
966
TIMC
T
H
  • Locked
CZ527 6.5 grendel varmint
Replies
6
Views
427
rayatphonix
R
Back
Top