SIGforum.com    Main Page  Hop To Forum Categories  Mason's Rifle Room    AR Barrel to Upper Fit Question
Go
New
Find
Notify
Tools
Reply
  
AR Barrel to Upper Fit Question Login/Join 
Life's too short to
live by the rules
posted
My latest rifle build is going to be a takedown rifle using the LEO Takedown system. For this to work correctly, I need a nice smooth easy barrel to upper fit so the barrel can be easily removed. After doing some test fitting last night, the barrel to receiver fit is VERY tight. The barrel will not seat all the way. If this was a normal build, no problem, a little muscle/heat/cold/lube and I would be ok, but in my situation that's not going to work.

So, I need to remove some material to get this to fit correctly. Should I lightly sand the ID of the receiver or the OD of barrel extension or maybe a little of both? Any other ideas? Any help would be greatly appreciated.

Chris
 
Posts: 1546 | Location: Richmond, VA | Registered: August 04, 2004Reply With QuoteReport This Post
is circumspective
Picture of vinnybass
posted Hide Post
I'd say do the barrel extension simply for the ease of doing it on the OD (outside diameter).

But, it might help to know which piece, if any, is out of tolerance.



"We're all travelers in this world. From the sweet grass to the packing house. Birth 'til death. We travel between the eternities."
 
Posts: 4719 | Location: Las Vegas, NV. | Registered: May 30, 2009Reply With QuoteReport This Post
Member
Picture of trebor44
posted Hide Post
Mark it (markon or magic marker) and look for 'tight' spot or just smooth or reduce down as suggested.


--------------------------------

On the inside looking out, but not to the west, it's the PRK and its minions!
 
Posts: 500 | Location: Idaho, west of Beaver Dicks Ferry | Registered: August 22, 2012Reply With QuoteReport This Post
Member
Picture of m499
posted Hide Post
Just ram it in there a couple hundred times 'til it loosens up. Wink Big Grin

All joking aside, I'd personally prefer to smooth out the I.D. of the receiver similar to how people hand lap scope rings. Only doing a couple passes at a time before re-checking fit.


___________________________

Just get the Springfield Pro...
 
Posts: 2569 | Location: USA | Registered: January 30, 2001Reply With QuoteReport This Post
Member
posted Hide Post
I expect that your upper is Anodized, a chemical process that produces a thin and extremely hard layer of aluminum oxide. Opening up the ID on the upper will remove that protective layer. To me the obvious answer is to reduce the OD on the barrel extension. As someone with access to a Lathe it's also the far easier choice.

One thing about your plans does concern me. That is the effect on accuracy. I have always believed that the ideal fit between upper and barrel is one that requires a bit of force to get everything "home". That way there aren't any vibrations going on between upper and barrel while a round is transiting the barrel. With no experience at all with the system that you are using I'm just speculating. Just bringing it up as a talking point. Love the idea of an easy barrel swap and don't know where the pitfalls of building one of these rifles would be.


I've stopped counting.
 
Posts: 4666 | Location: Michigan | Registered: November 07, 2008Reply With QuoteReport This Post
Life's too short to
live by the rules
posted Hide Post
So based on the feedback here and from additional research, it seems there was about of 50/50 split on what part I should take material from so I decided to do little from both parts. I lightly sanded the barrel extension and inside of the upper. I used 800 grit sandpaper and went very slow checking the fit frequently. With just a little bit of sanding on both parts I was able to remove just enough material to get a nice snug fit that easily slides in and out. The anodizing on the receiver is still intact. In fact you can’t even tell it was sanded. On the barrel extension it removed just a tiny bit of the finish. It should be good to go know. Thanks for all the help.

Chris
 
Posts: 1546 | Location: Richmond, VA | Registered: August 04, 2004Reply With QuoteReport This Post
Life's too short to
live by the rules
posted Hide Post
quote:
Originally posted by cmparrish:
So based on the feedback here and from additional research, it seems there was about of 50/50 split on what part I should take material from so I decided to do little from both parts. I lightly sanded the barrel extension and inside of the upper. I used 800 grit sandpaper and went very slow checking the fit frequently. With just a little bit of sanding on both parts I was able to remove just enough material to get a nice snug fit that easily slides in and out. The anodizing on the receiver is still intact. In fact you can’t even tell it was sanded. On the barrel extension it removed just a tiny bit of the finish. It should be good to go now. Thanks for all the help.

Chris
 
Posts: 1546 | Location: Richmond, VA | Registered: August 04, 2004Reply With QuoteReport This Post
  Powered by Social Strata  
 

SIGforum.com    Main Page  Hop To Forum Categories  Mason's Rifle Room    AR Barrel to Upper Fit Question

© SIGforum 2020