AR Sponsor
Posted: 7/13/2014 11:14:56 AM EDT
|
I have been given the following dimensions for the depth to use. Are these correct for a .308?
The rear takedown lug portion .625 deep The rest is to be 1.250 deep Thanks |
|
Thank You very much!! I have been looking for a drawing that spelled it out for me. I saved the drawing to my desktop and enlarged it there.
There is a big difference for the rear takedown lug portion @ .625 deep vs. the .530 called for on the drawing. and mentioned elsewhere. Thanks once again. |
|
The rear lug pocket is .520" deep minimum to .530" Max.
The FCP is 1.250" -.000"/+.005, don't go less than 1.250" especially if you plan to coat/anodize/cerakote the FCP area. Also, if you plan to a drop-in trigger module like a Timney, CMC, or some other brand, they are very sensitive to having the correct FCP depth (minimum of 1.249") for proper function... I really like the drop-in trigger modules that will give you really nice and crisp 3-4.5 lbs. trigger pulls (most are single stage)...with the Wilson Combat/Wilson Tactical TTU models giving you the best and safest drop-in AR trigger modules made today in both single stage and 2 stage versions available thus far. Good Luck. |
|
Quoted:
Are you using a jig. I as because I have three different prints. And depending on the jig used will determine the location oof the pocket. And all of them have .630 depth and 1.250 for the dpms pattern I the above looks like is for a Armalite AR10 pattern The .525"/.530" rear lug pocket depth is the correct depth for both the AR-10 and AR-308 (DPMS Pattern) lower receivers with a .500" wide pocket...I have seen a few with a .630" depth but those are Incorrect... |
|
the three prints i have are all different pin locations and selector positions and pocket dimensions.
just saying if someone is using a jig they better know the dimensions of the pin holes prior to machining the pocket yes .530 is acceptable but .630 is rdias so i go .630 |
I just checked my RDIAS drawing, and it is .630 +- .005, so .630 it is 
Quoted:
the three prints i have are all different pin locations and selector positions and pocket dimensions. just saying if someone is using a jig they better know the dimensions of the pin holes prior to machining the pocket yes .530 is acceptable but .630 is rdias so i go .630 |
|
If one is specifically looking to use or has a DIAS, then a .630" depth is appropriate and yes the AR-15 lowers will
function just fine using the same .525" depth of cut, as a matter of fact many private builders are using this depth of cut for their AR-15 lowers for added strength...Again, the OP was asking this for the AR-308 DPMS pattern lower which of course use .276" diameter pivot and take-down pins, which are located .250" below the top deck center-line (Y Axis) ...Good luck. |
|
Had a lot of fun yesterday. Finally had the opportunity to mill my lowers.
The rear takedown lug portion on both came out @.528-.529. The trigger pocket on both came out @ 1.251-1.252. As I will be anodizing the lowers so I was pleased with the depths. I did come away with 2 questions. 1. The drawing above shows a thin bench on the side at .530 depth leading from the takedown pocket to the trigger pocket. My jig did not produce this bench. Is this a problem? 2. For some unknown reason on one of my lowers the pre-drilled hole for the detent spring and pin was opened up when I was milling the takedown pocket. I was using the jig and it did not happen on the other one. How big of a problem is this? Thanks for all your help, all the information provided guided me through this process. |
|
Actually I made a mistake on the description of the second problem:
2. For some unknown reason on one of my lowers the pre-drilled hole for the detent spring and pin was opened up when I was milling the takedown pocket. I was using the jig and it did not happen on the other one. How big of a problem is this? The actual problem is with the selector detent pin hole. It has opened up from the 3/8" hole down to the floor. Sorry for the confusion. The 80% lower and Jig came from Quentin Defense. |
AR Sponsor