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View Full Version : Clamp on gas blocks? how reliable?



Mr.Goodtimes
06-20-09, 15:34
I have a DD low profile gas block and was wondering, what are the chances of this thing coming loose? this is a fairly hard use rifle, and my only rifle. it gets shot about 5k rds a year and is used as a home defense gun, shtf gun, etc.. i DO NOT want the gas block loosening up, and im rather paranoid about it now because, before the DD clamp on gas block, i had a YHM clamp on gas block installed by spikes tactical. when i went to take the gas block off and install the new one, the screws on the yhm gas block were extremely easy to remove.

I highly doubt that spikes forgot to tighten down the screws properly, as they do good work. however, the rifle had less then 500 rds down the tube since the install, which has me worried.

I tightened the shit out of the screws on the DD block and also used rockset on them, it seems pretty solid but, idk...

my other option (more time consuming) is to get a Larue gas block and send the barrel off to ADCO to get it installed/pinned in place.

FMF_Doc
06-20-09, 15:40
I personally do not trust the clamp on gas blocks, however the ones that the set screws intersect the barrel like the original pin on FSBs in my experience are more stable.

The vertical set screws do not intersect the barrel and are more prone to being moved if bumped hard potentially causing gas leaks and failure of the weapon to cycle.

I am still a fan of the original colt style FSB, it is considered part of the barrel by the manufacturers and is solidly pinned in place.

I read an article in one of the gun rags written by Larry Vickers some time ago and he states almost the same sentiments that I hold, and went on to say that he doesn't consider any rifle with a clamp on block/fsb a serious tactical weapon.

My personal thoughts are on a plinker it's a non issue, but if you intend to do some hard training and actually use the weapon for what it was designed for then anything that could compromise the gas system is a no go, no matter what marketing hype or how "high speed" it looks.

Mr.Goodtimes
06-20-09, 15:51
thanks doc! not exactly the words i wanted to hear but, now i know what i need to do.

i pm'ed robb to see if i can work something out with him, my other route (if it wont take too long) is to order a barrel w/ pinned FSB from anvil arms and ill just shave it down and refinish it.

they have nice barrels w/ fsb for a little over $200 bucks, so id like to give them a try, especially with them being a florida company.

Frens
06-20-09, 16:01
I'm too a fan of standard FSB, anyway I was surprised when I read the torque test MilitaryMorons did on a Vltor FSB :eek:

http://militarymorons.com/weapons/ar.optics2.html

FMF_Doc
06-20-09, 16:10
very interesting read, and confirms my own experiences as well.

5pins
06-20-09, 16:51
I wonder if having it silver soldered would be an option?

Puffy93
06-20-09, 17:44
I use one and have never had any problems with it.

Mr.Goodtimes
06-20-09, 18:03
I wonder if having it silver soldered would be an option?

i was thinking and am considering possibly having the bolt head welded to the gas block.

if i had to get it off i could still cut the thing off, but short of that, with the bolts welded to the gas block, i seriously doubt the the gas block would be moving, ever.

FMF_Doc
06-20-09, 19:25
vltor vst (http://www.vltor.com/vst.htm) this one has caught my interest, I am waiting for the pinned version to come out.


the split ring designs seem better than the others and put a lot of clamping surface around the barrel, so with right attachment method I think for average joe use it would be fine.

Mr.Goodtimes
06-20-09, 20:22
vltor vst (http://www.vltor.com/vst.htm) this one has caught my interest, I am waiting for the pinned version to come out.


the split ring designs seem better than the others and put a lot of clamping surface around the barrel, so with right attachment method I think for average joe use it would be fine.

im not worried about the thing rotating or getting bumped out of place, especially since its covered by a larue rail. what im concerned with is the screws backing out.

i know a good little shop down the street from where i shoot, i think ill have them spot weld the bolt to the gb, that will def. erase any worries i have of the thing moving. if i have to get it off ill just cut it off and buy a new one. i think welding the bolts will be the best thing to do at this point.

RAM Engineer
06-20-09, 20:31
Just send it off to ADCO and have them pin a Vltor set screw gas block in place. Should be around $100 for the work, new GB and shipping.

Mr.Goodtimes
06-20-09, 21:09
Just send it off to ADCO and have them pin a Vltor set screw gas block in place. Should be around $100 for the work, new GB and shipping.

this sounds like a winning idea, ill call them monday and get an exact price and see if they have the VLTOR block in stock. i havent seen them in stock anywhere?

FMF_Doc
06-20-09, 21:32
if it's covered by the rail then it's a non issue.

Thomas M-4
06-20-09, 21:55
I was looking at a pic of the dd gas block http://www.danieldefense.com/?page=shop/detail&product_id=107 could you use different bolts with the shoulder and a extended head then you could safety wire the bolts together.
Looked around a little bit a found this [first pic shows a flush mounted bolt with a hole drilled in it for a safety wire] http://www.bayarearidersforum.com/forums/showthread.php?p=5031512 Does it look like that would work on the bolts for the DD low profile gas block?
If it could that would be better than welding it.

Mr.Goodtimes
06-21-09, 01:11
will jb weld hold up to the heat? im thinking i could drill notches in the heads/gb and then jb weld them together, then if i ever need to get the gb off i could just chip the jb weld off?

chadbag
06-21-09, 01:44
With the ones with the vertical screws, drill a small dimple down the threaded hole into the barrel a small bit, put some rockset in and torque the screw in down into the dimple.

VLTOR guy mentioned that to me when I was at the SAR show last Dec (he did not mention the rockset but I believe did mention some thread locker). I don't think those screws are coming out or the gas blocking is rotating no matter what the abuse.

Mr.Goodtimes
06-21-09, 02:11
With the ones with the vertical screws, drill a small dimple down the threaded hole into the barrel a small bit, put some rockset in and torque the screw in down into the dimple.

VLTOR guy mentioned that to me when I was at the SAR show last Dec (he did not mention the rockset but I believe did mention some thread locker). I don't think those screws are coming out or the gas blocking is rotating no matter what the abuse.

e guns, mine is the DD block, which is a clamp and uses horizontal screws. I think i got it stayin in place though. I first rocksetted the screws and then tightened the piss out of them, i then cut slits in the gas block and bolt heads and filled them with JB weld.

i actually feel pretty rest assured now, especially with the jb weld. this should hold for, well, about ever probably.

just to be on the safe side though, before i slid the rail back on i used a sharpie to draw some locating marks, so if the screws do loosen, ill be able to see.

chadbag
06-21-09, 02:20
e guns, mine is the DD block, which is a clamp and uses horizontal screws. I think i got it stayin in place though. I first rocksetted the screws and then tightened the piss out of them, i then cut slits in the gas block and bolt heads and filled them with JB weld.

i actually feel pretty rest assured now, especially with the jb weld. this should hold for, well, about ever probably.

just to be on the safe side though, before i slid the rail back on i used a sharpie to draw some locating marks, so if the screws do loosen, ill be able to see.

yeah sorry, was just responding to general comments from others.

I actually have the same one (DD) in my gun. It was super tight to get on my barrel anyway. I should put witness marks on mine as well to watch in case anything comes out. I think I just red loctited my screws in and torqued them. So far it has 3-4k rounds through it including a 3-day EAG/Pat Rogers class and a 2 day Vickers class plus practice and stuff and seems ok. I will watch it and see if and when it starts having a problem.

Mr.Goodtimes
06-21-09, 02:24
damn bro, that makes me feel a little better about using the DD gas block. i recon if you got 3-4k through it it probably aint commin loose. this should give me plenty of time to save up for something i can pin in place.

spamsammich
06-21-09, 03:34
If you torque the crap out of those flat socket cap screws and then stake them, they will not back out on their own. I used red loc-tite and lots of elbow grease, then staked them with a nail set. They ain't going anywhere.

Blankwaffe
06-21-09, 04:01
If you torque the crap out of those flat socket cap screws and then stake them, they will not back out on their own. I used red loc-tite and lots of elbow grease, then staked them with a nail set. They ain't going anywhere.

+1
That was the fix my local gunsmith recommended for the Armalite clamp on gas blocks on my 20" A4's.He reinstalled the screws with rockset and then staked the blocks into the screws and back staked the screws into the blocks.No problems so far and I have a couple thousand rounds through one of the uppers already.

spamsammich
06-21-09, 04:46
This hole is how I lined the block up on my gas port after marking the port location before removing the original FSB

http://web.me.com/supermarkus/iWeb/Site/Noveske%20Afghan%20build_files/IMG_1647.jpg

After torquing down well and red loc-tite:
http://web.me.com/supermarkus/iWeb/Site/Noveske%20Afghan%20build_files/IMG_1652.jpg

Staking:
http://web.me.com/supermarkus/iWeb/Site/Noveske%20Afghan%20build_files/IMG_1653.jpg

Finished product:
http://web.me.com/supermarkus/iWeb/Site/Noveske%20Afghan%20build_files/IMG_1654.jpg

STJ
06-21-09, 11:10
Using standard Red Locktie or JB weld on a gas block is about as useful as using Elmers glue. Both breakdown at temp bellow what a gas block reaches after a good amount of sustained fire. IE as seen in a carbine class.

Your best bet for a clamp on gas block, if you are worried, is to use rockset and or staking....just like a gas key.

Something to keep in mind, make sure the gas block is made from the same (or as close to as possible) material as the barrel so that they both expand as the same rate. An aluminum gas bloc will expand more than a steel barrel, and when hot enough will loosen up no matter how you have the bolts fixed.

Mr.Goodtimes
06-21-09, 20:05
its been staked and rocksetted, i dont think its going anywhere. mine appears to be off center on the inside of my rail, however, when using a level, the flats on the side of the gb are perfectly perpendicular to the top rail which is in turn perfectly square with the rail on the upper reciever.

it appears though that the upper portion of the gas block isnt perfectly symmetrical, and i know the bottom isnt anymore as i had to grind it, the bottom split though also appears to be off a little, which puzzles me, because if i move it slightly in either direction it looks like the gas tube is misaligned a little bit.