Lage 10/31 Upper Won’t Lock Open

[cbritt15]

New to me 10/31 just came in today. Went to function check and I am unable to get the bolt to actually lock back in the open position.

It goes far enough rearward to pick up a round, so if I went to live fire I am sure the entire mag/drum would be emptied.

Anyone ever seen and/or fixed this problem?

I haven’t run into this issue with any other upper (factory, Lage 10/9 mk2, Practical Solutions Fat Ghost), so I am at a loss.

Picture for attention

 

[Deerhurst]

Any VBS buffers? How far from being caught by the sear does it stop moving?

 

[cbritt15]

Any VBS buffers? How far from being caught by the sear does it stop moving?

Forgot to mention- no VBS installed. Seems like its either right at the cusp of being caught by sear, or already past and not being caught

 

[cbritt15]

After some additional tinkering, appears the bolt is hitting the outer edges of the double feed feed lip. Odd the mk2 upper doesnt have the same affect considering both are double feed bolts.

We’ll see if i can get the carbon locked feed lip removed for grinding, otherwise looks like ill just be grinding while attached

 

[cbritt15]

Update- grinded off maybe 1/16 of an inch total on both sides of the feed ramp ears. Took about 9 grind and test fit sessions to make sure i didnt remove too much. Polished it off and am now good to go and upper test functions fine.

Also tested on all other uppers so no issue there either.

 

[oziner399]

Had the same issue on my Fat Ghost build, turned out the buffer was just a hair too long and short-stroking the bolt. Swapped in a slightly shorter one and it locked back like a champ

 

[cbritt15]

Had the same issue on my Fat Ghost build, turned out the buffer was just a hair too long and short-stroking the bolt. Swapped in a slightly shorter one and it locked back like a champ

In this case where I stated it was close, if not already passed the sear, was wrong- the stroke length of the 10/31 is evidently significantly longer than I was anticipating. Once I cleaned up the feed ramp edges, the bolt was able to travel another 3 inches or so to actually catch the sear.

Would have been nice if that was the case for this one, unfortunately modifying the gun was the only option instead of modifying the bolt. Luckily it is just a feed ramp that can be removed (didn’t say it would be easy LOL) and replaced!

 

[cbritt15]

Speaking of the feed ramp, in my limited experience I have only seen the weld in style feed ramps offered, but never a bolt on option like is installed in my receiver.

You can see (ish)- it is a hex head bolt going through (red indicating direction) into a threaded plate (blue indicating the plate). Does anyone know where a spare bolt on ramp can be acquired? Any removable/replaceable part, I’d like to have spares of.

Unless that is of course, one of the weld on styles that the previous owner drilled and tapped.

Thanks!

 

[m11stuff@hotmail.com]

I’m pretty sure that is not an OEM feedramp. As far as I am aware, the M-10 feedramps are thinner gage steel and welded in. Looks like a DIY repair job.

 

[brenbuilds]

I have never seen a feed ramp bolted on. That is wacky.

 

[cbritt15]

I have never seen a feed ramp bolted on. That is wacky.

Nor have I - it’s has been so carbon fouled i hadnt even noticed it until now.

I guess I’ll bust out the elbow grease later to clean it up and take better pictures for documentation!