Out of spec lowers etc

[mtrmn]

Just skimmed over the thread titled "Buffer made of brass" and saw a few posts arguing over the proper placement of the buffer retainer. I'm not getting into that argument but I do have a cheap fix for the problem that has worked for me in both of my past builds that chewed up the buffer face due to contact with the buffer retainer while firing. This is an AR15, but there's no reason it won't work with any AR variation.

You don't have to scrap your lower or upper, nor do you have to buy a whole bunch of added expensive parts to change the geometry of your effed up gun. All you need is access to a lathe or get a machinist to make one simple cut on the easiest-to-replace part involved. The pictures tell the tale much better than I can word it. I see no reason whatsoever that this won't fix the problem 100% of the time.

[jtallen83]

That looks like a pretty good solution. Not knowing a machinist that won't charge me it is cheaper to buy the offset retainer for me.

[mtrmn]

Didn't know an offset retainer even existed. Back when I was dealing with this problem everybody told me my lower was trash and I needed to go with a BCM or whatever their favorite brand is.

[jtallen83]

2 minutes ago, mtrmn said:

Didn't know an offset retainer even existed.

This retainer and the Tubbs carrier weight are solutions, can't find the Tubbs anymore though. 

https://gallowayprecision.com/offset-buffer-retainer-for-AR-15-rifles

[98Z5V]

Great idea for the machining of the buffer face - and that defilitely solves the issue, and gets the buffer in contact with the back of the BCG, and pushes it off the retainer, just like it's supposed to.

I'm with Jim, though - David Tubb doesn't make the CWS anymore, the the offset pin is a very easy solution.

Despite what anyone argues - the design of the lower is a 6* forward offset for the pin, and lowers that are drilled straight-up vertical for the pin are not right, and will cause issues. 

[mtrmn]

Thanks for the Galloway link. Didn't have time to browse much, but looks like they got a LOT of interesting stuff like Ruger LCP short stroke triggers etc. Def bookmarked that site.

When I had my buffer problems was back during the Obama years and AR lowers were hard to find. I got a few Superior Arms lowers through my LGS and 2 of them had this problem. Only info I could find on the net was people saying the lower was worthless and would have to be thrown away and replaced with whatever the flavor of the week was.

I started experimenting and figuring out how to save these trash lowers and make them run 100%. Went through a lot of trial and error and finally realized the buffer needed to be further forward in order to be further back when the gun was assembled. I had access to a lathe at work and turned a buffer down just to see. Since then both of the problem guns have run 100%.

As for the design specs, I didn't know the specs at the time. I just knew the specs weren't right. All I cared about was fixing the problem so as to NOT have to trash the serial-numbered part of an otherwise perfectly good gun. "Po' folks got po' ways" is how the older generations around here put it.

[98Z5V]

9 hours ago, mtrmn said:

Thanks for the Galloway link. Didn't have time to browse much, but looks like they got a LOT of interesting stuff like Ruger LCP short stroke triggers etc. Def bookmarked that site.

When I had my buffer problems was back during the Obama years and AR lowers were hard to find. I got a few Superior Arms lowers through my LGS and 2 of them had this problem. Only info I could find on the net was people saying the lower was worthless and would have to be thrown away and replaced with whatever the flavor of the week was.

I started experimenting and figuring out how to save these trash lowers and make them run 100%. Went through a lot of trial and error and finally realized the buffer needed to be further forward in order to be further back when the gun was assembled. I had access to a lathe at work and turned a buffer down just to see. Since then both of the problem guns have run 100%.

As for the design specs, I didn't know the specs at the time. I just knew the specs weren't right. All I cared about was fixing the problem so as to NOT have to trash the serial-numbered part of an otherwise perfectly good gun. "Po' folks got po' ways" is how the older generations around here put it.

How far did you turn that buffer face back?  The Tubb CWS pushed the buffer back another 0.080", and it fixed ALL of these problems. 

Just curious how far you went, and it solved it.  0.080" was the answer, on the old-school CWS. 

[mtrmn]

According to the date on those pics it's been almost 9 years. I know it wasn't much at all. Looking at the first picture very closely it looks to be maybe 20 to 25% of the diameter of the buffer retainer tip. I still have and use the guns, I can measure tomorrow.

[98Z5V]

5 minutes ago, mtrmn said:

According to the date on those pics it's been almost 9 years. I know it wasn't much at all. Looking at the first picture very closely it looks to be maybe 20 to 25% of the diameter of the buffer retainer tip. I still have and use the guns, I can measure tomorrow.

That's still good stuff - solving that problem from way back in the day - and that solves it.  I love it.  

[mtrmn]

I turned down about half a dozen of those buffers although I only needed 2. Just in case of future problems.

Measured 4 of them and the depth of the step is only 0.035".

The width of the cut into the diameter is 7/64" or 0.10938" . Just enough to clear the tip of the retainer and still have enough contact surface for the bolt carrier to push against.

Remember, this is for an AR-15, not a .308 if it makes any difference.

Edited April 19, 2021 by mtrmn
add info

[98Z5V]

14 hours ago, mtrmn said:

I turned down about half a dozen of those buffers although I only needed 2. Just in case of future problems.

Measured 4 of them and the depth of the step is only 0.035".

The width of the cut into the diameter is 7/64" or 0.10938" . Just enough to clear the tip of the retainer and still have enough contact surface for the bolt carrier to push against.

Remember, this is for an AR-15, not a .308 if it makes any difference.

Dimensions would be identical for a .308AR - same buffer diameters, same receiver extension diameters, same buffer retaining pins.   That's some damn good info, right there, man!