ArmaLite AR-10(T) - Initial Thoughts / Questions

[BigNate]

So - I've recently picked up an ArmaLite AR-10(T) and I got out this weekend and put a few rounds through it.  The glass that came with it is pretty basic and I'm pretty rusty -  and given these things I'm really happy with how it shot.   For whatever reason I took a photo of the first group but no others.    Anyway - the first 100 yard group is posted below - and I knew the flyer was a flyer when I let it go...  

So - one question... The cam from the BCG has a noticeable groove in it (see the red oval).   I know in the auto engine world anything that can "catch a nail" is a problem - and I can catch a nail in this thing.   I'd guess it is a few thousandths deep.   I've never seen this sort of groove in an AR-15 platform cam - not sure how worried I should be? 

 

Edited June 14, 2021 by BigNate
Extra info

[mtrmn]

I would replace that. JMO

I'm assuming this is a used gun? That particular part needs to be well lubed. Probably best with grease. I've replaced a few of those in AR15's and it made a difference in smoothness of movement when cycling by hand.

Edited June 15, 2021 by mtrmn
extra info

[jtallen83]

8 hours ago, BigNate said:

not sure how worried I should be? 

I'll let you worry for me. Somewhere north of 3,000 rounds on this cam pin from a 10-B, always kept it greased, didn't always put it back in oriented in the same way but I figured if I just put it in at random it would even out the wear, it's pretty evenly worn anyway. I have spares so I should really swap it out but my dumb arse just put it back in the gun after these pics, maybe next time.........

[98Z5V]

11 hours ago, BigNate said:

So - one question... The cam from the BCG has a noticeable groove in it (see the red oval).   I know in the auto engine world anything that can "catch a nail" is a problem - and I can catch a nail in this thing.   I'd guess it is a few thousandths deep.   I've never seen this sort of groove in an AR-15 platform cam - not sure how worried I should be? 

That's probably carbon buildup.  Scrub the hell out of that ring with a good brass-brush and some solvent, and I'll be that it "disappears."  That's not a groove in the cam pin - that's old shiit left over, from firing.  Your nail isn't catching on a groove - it's catching on a ridge of carbon...  

If I'm wrong, I'll buy it from you as a spare. 

[BigNate]

8 hours ago, 98Z5V said:

That's probably carbon buildup.  Scrub the hell out of that ring with a good brass-brush and some solvent, and I'll be that it "disappears."  That's not a groove in the cam pin - that's old shiit left over, from firing.  Your nail isn't catching on a groove - it's catching on a ridge of carbon...  

If I'm wrong, I'll buy it from you as a spare. 

Pretty sure that it is an indentation - but I'll pull it apart tonight and be sure.   Sounds like I'll replace it - and keep it as a spare... 🙂

[BigNate]

10 hours ago, jtallen83 said:

I'll let you worry for me. Somewhere north of 3,000 rounds on this cam pin from a 10-B, always kept it greased, didn't always put it back in oriented in the same way but I figured if I just put it in at random it would even out the wear, it's pretty evenly worn anyway. I have spares so I should really swap it out but my dumb arse just put it back in the gun after these pics, maybe next time.........

Thanks sir... same pattern.   and it looks like yours is deeper.   As noted in the other reply - I'm guessing I'll buy a replacement and keep this one as a spare... 

[edgecrusher]

While it looks bad it’ll be ok

[Cliff R]

+2

It's probably good for 60,000-70,000 more rounds thru it before it's worn deep enough to cause any issues.......IMHO....

[Sisco]

The AR10T’s tend to be tighter tolerances then a standard 308AR to maximize accuracy. Tighter tolerances=things wear out faster. I looked at mine and it isn’t quite as pronounced, but it is there.