Aero M5 Doesn't Cycle M80

[Sureshot732]

Hey everyone. I am having some issues with a new M5 and I was curious if anyone had any insights into the issue.

New M5, Stock complete upper with a 20" barrel and a rifle buffer system.

It doesn't like M80 for some reason. I put about 100 rounds of M80 through it and it wouldn't lock back or cycle. After some heavy oiling and hand cycling, I picked up some .308, and it started to cycle. Once I put a couple of boxes through, I tried to go back to the M80 to see if it was a break-in thing, but as soon as I put the M80 in I started having the same issue.

Any thoughts on why this thing isn't liking the NATO rounds? Is it just a break-in issue? I think the .308 is a higher pressure round, so I was thinking it just needed that extra oomph because it's still a little stiff. The gas block is not adjustable and it was installed at the factory, so I am thinking it's good. When I run it with .308, there are zero issues. Cycles, locks back on empty, and shoots great, but I would like to have the option to use M80 if needed.

I have been digging into this issue for weeks and I just thought I'd reach out here. Thanks in advance!

 

[wade2big]

Seems like you figured it out already. You can check the gas block to make sure it is aligned correctly with the gas port in the barrel if you hadn’t already.

 

[greg1147]

I had the same issue with not locking back, but I am running a carbine stock buffer. It turned out that the buffer spring is a coil shorter that the regular carbine spring and the buffer is smaller/lighter maybe because of the weight of the BCG but now it runs fine. Little over gassed with a suppressor but that just an adjustment in the AGB. BTW this is a 6.5 CM 18" barrel

 

[gixxer822]

Welcome to the club or aero/ BA issues.

 

[hlee]

Lighter buffer and/or lighter spring. The JP SCS builder kit is designed for these kinds of "issues..."

 

[RUTGERS95]

Lighter buffer and/or lighter spring. The JP SCS builder kit is designed for these kinds of "issues..."

bingo

I had the same issue and actually cut a 1 1/2 coil off a power spring and bam, problem solved. Was using surplus 308 as well

 

[bfoosh006]

When you say M80, do you mean USGI / LC M80 ?

Or another brand ?

I guess I should just ask , What specific brand M80 ?

 

[RUTGERS95]

When you say M80, do you mean USGI / LC M80 ?

Or another brand ?

I guess I should just ask , What specific brand M80 ?

LC M80 for me