hired_gun Posted May 15, 2015 Report Share Posted May 15, 2015 I bought a new DPMS .308 barrel in the carbine style profile. It came with the A2 style sight and that was about it. The sight was pinned on. When I removed the sight to install the handguard end cap the sight won't go on properly; that is, the pin holes don't line up because of the width of the handguard cap. Shy of putting on some sort of floating handguard is there another "fix" I can use? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2015 Report Share Posted May 15, 2015 Pics are damn near mandatory on this one. What was it stock, what did you take off, what did you put on, what doesn't fit now? Throw us a bone here, and help us out. Pics. Pics. Pics. Or GRAPHIC explanation. Your call. Manufacturer of said barrel - is it really DPMS, or is it someone else, but "DPMS Patterned?" You need more details, or this is helpless. I'm just sayin'... Quote Link to comment Share on other sites More sharing options...
hired_gun Posted May 15, 2015 Author Report Share Posted May 15, 2015 Typical 18 inch carbine profile barrel. The only thing it had was the A2 style front sight. No sight post, spring pr detent. The sight was pinned to the barrel with 2 tapered pins. I was obvious when the sight came off that it was on when the barrel went into the finish tank as the metal was white under the sight. It was just a barrel that was purchase with plans to make a weapon, so no other "parts" were with it. I will try to upload pictures if needed later today Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 15, 2015 Report Share Posted May 15, 2015 (edited) Sounds like the hand Guard cap is keeping the Tapered Pin holes from lining up . Most likely the Barrel Manufacturer did not leave room for the Hand guard cap for std A2 hand guards , when they turned the Barrel for a gas block . If you plan on using the A2 type sight /gas block , Remove the sight & remove some material from the face of the sight where the HG cap sits against , that will let the Pin holes line up & enough to keep the Cap snug against it . Edited May 15, 2015 by survivalshop Quote Link to comment Share on other sites More sharing options...
hired_gun Posted May 15, 2015 Author Report Share Posted May 15, 2015 I considered that. I also considered removing some of the shoulder of the barrel. In reality that would be a lot less area. Sound like a plan? Quote Link to comment Share on other sites More sharing options...
blue109 Posted May 15, 2015 Report Share Posted May 15, 2015 was the barrel nut on there already? Another option if you want to keep a fixed front sight...armalite sells a clamp on fsb. I think they are around $40 Quote Link to comment Share on other sites More sharing options...
GRA Posted May 16, 2015 Report Share Posted May 16, 2015 WOW ... Glad I saw this thread on here. I was considering one of these barrels. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 16, 2015 Report Share Posted May 16, 2015 I considered that. I also considered removing some of the shoulder of the barrel. In reality that would be a lot less area. Sound like a plan? If you have a lath to turn the barrel , would be easy . I always tend to alter inexpensive , easily replaceable components , though another A2 gas block , the pin holes may not line up with the one on now . I would have the A2 sight gas block milled or the flat part of a fine grinding wheel , would make short work of it , being careful & not too aggressive , it won't need much , ether way . Quote Link to comment Share on other sites More sharing options...
GRA Posted May 16, 2015 Report Share Posted May 16, 2015 "I would have the A2 sight gas block milled" +1 ... to add to this you can also have whoever is doing the milling also knurl the back side of the sight (I mean the part that faces you when you're sighting down the barrel) to help reduce glare. This seem to be getting popular these days. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 16, 2015 Report Share Posted May 16, 2015 I'd cut the sight back, and not the barrel - just measure the thickness of the handguard cap, and that's what comes off the sight back. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 17, 2015 Report Share Posted May 17, 2015 I know these guys are trying to fix your situation and keep your rifle as near as possible to original, but.... You have an 18" carbine length barrel. That should have been a mid length or even a rifle length barrel. Now it is highly likely that your rifle is going to be over gassed. My opinion would be to ditch the FSB and get yourself something adjustable. An adjustable GB will greatly enhance your shooting experience later, and costs a lot less than a heavy buffer system. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 17, 2015 Report Share Posted May 17, 2015 Seems the OP wants to use A 2 hand Guards <dontknow> I can spend his $$ as good as you ! Free Float Hand Guard , Aj. Gas Block ,& BUIS & still get a Heavy Buffers , Buffer / Spring <laughs> Quote Link to comment Share on other sites More sharing options...
mrmackc Posted May 17, 2015 Report Share Posted May 17, 2015 Pictures please or how far off are the pinning holes on the fsb/gb? Inches? Millimeter? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 18, 2015 Report Share Posted May 18, 2015 The pin holes in the barrel will be off be exactly the thickness of the handguard cap. Someone around here knows the standard thickness measurement. It ain't inches, but it's in thousandths. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 18, 2015 Report Share Posted May 18, 2015 (edited) The pin holes in the barrel will be off be exactly the thickness of the handguard cap. Someone around here knows the standard thickness measurement. It ain't inches, but it's in thousandths. Probably the shoulder on the Barrel was not cut back far enough . 0.030" . Kinda makes you wonder , I would think they would have the Gas system or Gas Port , to the correct spec.? Edited May 18, 2015 by survivalshop Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 18, 2015 Report Share Posted May 18, 2015 If the gas port is out of spec, this could cause issues with the gas tube later. That fraction of an inch could mean the tube gets smashed in the gas key. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 18, 2015 Report Share Posted May 18, 2015 One would hope its just the Gas block shoulder on the Barrel that's not cut back far enough . <dontknow> Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 19, 2015 Report Share Posted May 19, 2015 I have a more sickening presumption that whoever drilled the taper pins on this barrel, bottomed out the FSGB without thinking. Now the taper pins are in the wrong spot. A new barrel, sold with a preinstalled A2 style FSGB, should ALWAYS include an installed handguard cup (round or triangle) as well. That's just common sense. Personally... send it back to the company with a polite request to unfuck their mess. Quote Link to comment Share on other sites More sharing options...
blue109 Posted May 19, 2015 Report Share Posted May 19, 2015 I have a more sickening presumption that whoever drilled the taper pins on this barrel, bottomed out the FSGB without thinking. Now the taper pins are in the wrong spot. A new barrel, sold with a preinstalled A2 style FSGB, should ALWAYS include an installed handguard cup (round or triangle) as well. That's just common sense. Personally... send it back to the company with a polite request to unfuck their mess. This. That's why I asked if it had the barrel nut on it. A pinned FSB is suppose to be a somewhat permanent install. Why would you ship that without a cap? You are requiring the user to remove the sight no matter what they want. Quote Link to comment Share on other sites More sharing options...
GRA Posted May 19, 2015 Report Share Posted May 19, 2015 I spoke with a tech on the phone yesterday about just such a barrel. I was told they were informed that some of these barrels were done in this manner (without the hand guard end cap) on purpose as they expected the top post portion to be cut off so the remaining portion could be left intact and used as a low-profile gas block for a quadrail setup that still afforded the use of a bayonet mount. I've seen an article once in a magazine about doing this but I've never seen it. Who knows ... it may work. Personally I prefer the A2 front sight gas block as it was originally intended. I'd send the barrel back if this was indeed what I wanted. Quote Link to comment Share on other sites More sharing options...
blue109 Posted May 19, 2015 Report Share Posted May 19, 2015 I did that on my first AR. works in a pinch if you don't want to buy other parts...but to ship one like that is stupid. Why go through the added expense of drilling and pinning? You can buy clamp on low pro blocks dirt cheap. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 20, 2015 Report Share Posted May 20, 2015 I did that on my first AR. works in a pinch if you don't want to buy other parts...but to ship one like that is stupid. Why go through the added expense of drilling and pinning? You can buy clamp on low pro blocks dirt cheap. I think they screwed some of them up & its their explanation to cover their A$$'s . Ya , we did that on purpose , ya , right ! Quote Link to comment Share on other sites More sharing options...
GRA Posted May 21, 2015 Report Share Posted May 21, 2015 I think they screwed some of them up & its their explanation to cover their A$$'s . Ya , we did that on purpose , ya , right ! Very likely I have to agree also Quote Link to comment Share on other sites More sharing options...
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