I have a BCM barrel that is dimpled. I am using a larue gas block and red loc tighted the set screws. I have/will run the carbine hard and the barrel deff gets very very hot. Will the heat from the barrel loosen the red loct tite?
|
||||||||||||||||||||||||||||||||||||||
I have a BCM barrel that is dimpled. I am using a larue gas block and red loc tighted the set screws. I have/will run the carbine hard and the barrel deff gets very very hot. Will the heat from the barrel loosen the red loct tite?
How are you guys lineing up the gas port? I installed a 2 piece gas block on my SPR build. I made up a pin that fit snug in the gas block top and tapered it to fit in the gas hole to get proper alignment before I installed a set screw. I also had to dimple the barrel. That is not possible with the Voltor gas block. I am thinking about installing a pinned gas block and did not know how this was done.
Jk
If you are doing an Vltor and using the dimpling jig it has a set screw that aligns it automatically with the gas port. That is the easy way. I have the jig on order but in the past I just marked a line on the barrel forward of the gas port and marked the front of the block in line with the gas port. I assembled the block, tightened down the set screws (not dimpled) and test fired the rifle. If it functions fine they are aligned and you can check easily by taking the block back off and looking at the top of the barrel. There will be a dark ring around the port where the port in the block was and you can see how well centered it is. The port in the block is significantly larger and there is some room for error, they don't have to be perfectly concentric.
If it fired fine and the ports were aligned by checking the carbon deposits I will turn the barrel over and dimple it where the set screws scratched the barrel, reassemble, and loc-tite the set screws. Test fire again and if all is well, drill and pin it. I would never pin the block until I knew the rifle was functioning because once the pin hole is drilled you are done adjusting.
ETA: If you are installing a railed gas block with a railed free float quad rail you can use the rail alignment tool from Brownells. I have one and love it. I use it to install the quad rail perfectly in line with the upper and then the block perfectly in line with the quad rail. I've never had the gas ports off after doing this but as mentioned before, pull it off after shooting to check the carbon circle around the gas port.
Last edited by Altair; 11-07-10 at 10:57.
Advanced techniques are the basics mastered.
Excellence is an art won by training and habit. We are what we repeatedly do. -- Aristotle
Pistol/Shotgun/Rifle Instructor
Sig/Remington/RRA/Sabre Armorer
Makes perfect sense. Thank you.
Jk
Update:
I haven't done an Vltor gas block yet (or any close enough to use the dimple and drilling jig) but I have now done 3 pins in railed gas blocks (all on my rifles, so if I screw up it isn't someone elses gun). In all three cases I had to drill an angled surface first but was able to get it to work by putting the bit almost all the way into my press with just about 1/8" sticking out of the press. I'd drill down just under 1/8" then reset the bit to 1/4". Did this increasing the length of the bit until I drilled all the way through and it worked fine. The holes aren't 100% straight (slightly angled from the 90 degree ideal) I think from very minor drill bit flex but you have to measure each side of the block to tell and all three were clean and just grazed the barrel by about half the size of the bit so I'm very happy with the result.
I reamed them using the Brownell's 2/0 reamer. It has a screw driver handle and doing it by hand was cumbersom but I found a deep well 15mm socket slipped over the handle and held well, making the reaming much easier. After that I just hammered in the taper pins.
Now all three blocks have pins and are rock solid. I checked by taking out the set screws and trying to move the block. None would budge. Of course I put the set screws back in (with locktite) just because.
I did learn that doing this with a .750" gas block seat is much easier than a .625". I measure and marked and then measured and marked and sweated drilling the .625" because there isn't a large margin for error. I got it right the first time, but I would hesitate to do someone elses rifle with a .625" seat without some sort of jig.
Last edited by Altair; 11-27-10 at 16:02.
Advanced techniques are the basics mastered.
Excellence is an art won by training and habit. We are what we repeatedly do. -- Aristotle
Pistol/Shotgun/Rifle Instructor
Sig/Remington/RRA/Sabre Armorer
NECRO-post!
Where are you folks sourcing your taper pins when you pin a gas block? I see that 87ind has a nice splined taper pin that I would LOVE to grab for my next project. Thanks in advance.
"That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892
"The body cannot go where the mind has not already been."
If I was going to install it myself I'd just buy one of the Geissele gas blocks that includes the taper pin:
http://geissele.com/supergasblock.aspx
That was my other option. Either drilling a BCM .750 block (or equivalent) or getting a geissele. However, as good as the roll-pin appears (and I"m sure it's more than adequate for the task), a taper pin like that found in this kit by 87ind seems stronger and....well...more "bombproof":
https://www.rainierarms.com/?page=shop/detail&product_id=3939
My searches have turned-up nothing so far, so the GA gasblock is prolly gonna get the nod. I'm using an RA Mountain series 18" barrel with rifle gas. It isn't dimpled, so I need to do that as well. Gonna be on a patrol upper, so I definitely want it to be pinned.
Also, going to use the McMaster-Carr knurled GB screws as rec'd by IG after I dimple the barrel:
http://www.mcmaster.com/#90289a337/=pj95k2
Then gonna use either Rocksett, Red Loctite 271, or Resbond 907TS and a dab of green Loctite between the GB and the barrel as rec'd by Grant.
Yes, it's overkill. Nobody every complained of a gas block that was secured "too well". However, I've seen plenty of guns go down because one wasn't secured well enough. Lil-bit of OCD about this as well.
Last edited by BufordTJustice; 11-25-13 at 15:11.
"That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892
"The body cannot go where the mind has not already been."
If anyone needs 303 stainless steel #2/0 x 5/8 in. taper pins shoot me a PM.
Bookmarks