Jump to content
308AR.com Community
  • Visit Aero Precision
  • Visit Brownells
  • Visit EuroOptic
  • Visit Site
  • Visit Beachin Tactical
  • Visit Rainier Arms
  • Visit Ballistic Advantage
  • Visit Palmetto State Armory
  • Visit Cabelas
  • Visit Sportsmans Guide

Hit a impasse... Which part goes under the knife?


Recommended Posts

Using a Mega MaTen receiver set, I'm finding out the rail height differences have their drawbacks...


I'm using a Precision Reflex carbon fiber tube and flip up front sight / gas block...  The curve ball is the "height" of the front sight itself...  The combination of the "regular" DPMS forearm and taller (Armalite/DPMS "high") front sight led to this condition...






There's rougly .125" of interference, thus the sight can not lay flat when folded down.  Leaving it alone is way more than enough to drive me nuts!  That said, my options seem to be...  (A) I clearance the forearm (carbon fiber) just enough to accept the sight hood in it's down position...  OR ( B)  I fire up the mill and remove enough material from the sight hood to clear the tube...  Basically transforming the shape into a more of a "HK" style rather than a full hood.  I've tried every different combo of assembly and spacing of the G.B. I can think of and it appears...  Something needs to get cut.


My impasse...  Which way do I go?  Either mod is very do-able...  Which way would you go?  Or am I over looking a way to create the needed room? 

Link to comment
Share on other sites

Not having access to a means of drawing on the photo here from my phone...instead of a square cut, you could slope it towards the front and no one would ever know. It wouldn't look like a relief notch at that point. Just one straight line if you get what I mean.

Link to comment
Share on other sites

In the gunsmithing business, the old axiom is.   Work on the cheapest part. in case you need to replace it. 





I will endorse this - to an extent.  I know what the PRI carbon fiber rail price is.  I know what the PRI front sight cost is.  I've done two builds with those parts.  If you cut up the front sight, you will be working on the cheaper part.  However, even if the front sight were the more expensive part, I wouldn't fuk with the carbon fiber rail.  Don't fuk with the structural integrity of carbon fiber parts.


Don't fuk with the structural integrity of carbon fiber parts should be the new axiom of gunsmithing.  You can't undo that, no matter what.

Link to comment
Share on other sites

Don't fuk with the structural integrity of carbon fiber parts should be the new axiom of gunsmithing.  You can't undo that, no matter what.


Take it from someone who works/has worked on carbon fiber on a regular basis -- you can't fück up the integrity on that carbon fiber tube if you notch it. It'll take a lot to fück the integrity up on that thing. Besides, carbon fiber is easy to repair, IF you know how.  :))


If it's "real" carbon fiber, you can grind it off to form a notch very easily, but given what you have, I'd notch the front sight.  Tom would just take a hammer to it and beat it into submission. 

Edited by shibiwan
Link to comment
Share on other sites

That tube is real carbon fiber.  I've beat people to death with that thing, out here in the real world.  Don't mess with that tube.  <thumbsup>


It's not car fairings, and $hit.  <dontknow> :banana:

Edited by 98Z5V
Link to comment
Share on other sites

Thanks for all the suggestions!


I have contacted PRI and am currently awaiting their response.  Also...  The barrel has been sent out and will be back in a couple weeks so I still have time to formulate a course of action.  I have an idea of where I'd like to take this but it's tough to explain...  I'll hit the Paint program and see if I can make a couple scrbbles for you folks...  Hang tight, it may take a while as I've never been accused of being an artist...

Edited by moose-hunter
Link to comment
Share on other sites

Okay...  Don't laugh!  I know it's not the latest release of AutoCAD or SolidWorks...




Let's see if I can explain my possible plan...


Very basically, the height dim in red ("A") is the amount I need to remove in order for the sight to lay flat with just a bit overlapping the PRI tube.  Without the barrel, I don't have exact numbers but it would amount to removing +/- .095".  Less than half of the "flat" you see on the top of the sight hood.  The raidus at the end of the pass, nearest the hinge, doesn't really matter and will end up being what ever the radius of the tooling is. Or it would end up at 90*...  Depending on the direction of the cut.  With this also being the gas block, I can mount and fit this and the gas tube, then cut the sight to suit.  Finishing the cut will be either with a flat, non-reflective black paint.  I found some that is VERY close to the original color,  OR...  My buddy, who runs a metal coating business, said he'd give it a go and match it as best he could.  Either way, as long as it's close, and uniform from top to bottom, it will only be noticable when when the irons are deployed.  Which hopefully will only be to dial them in.  If they're need after that, I'll have more to worrie about than finishing since the $2K+ piece of glass on top of the rifle has just gone FUBAR...


I hope I explained that correctly...  Your thoughts?



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...