View Full Version : Gas Block Loose Around Barrel
Howdy all,
So I'm having some technical difficulties on my current build. Ive purchased an SLR rifleworks series 7 adjustable gas block that is .750 in diameter, to go along with my seekins precision 8" SS .300 blk barrel, which is .750 at the gas port.
Ive read that there are some variations in the diameter depending on the company, but this is unsettling. The block swings easily around the port without oil, and I can feel the wiggle space.
The gas block is a set screw block, will it tighten up at the port when I tighten these down??
Any help is appreciated
Thanks all!!
Do you have some calipers to measure the barrel and the gas block? If not, I would contact both manufacturers.
Do you have some calipers to measure the barrel and the gas block? If not, I would contact both manufacturers.
Not at the moment, but I'm in need of some and now is as good a time as any to purchase. Recommendations??
This is just an annoyance, considering both manufacturers are held in high regard.
Short story for you. BCM was noticing that their GB's were not being held to the correct sizes (.740 and .625). So they ordered them slightly oversized and hand hone them to the correct dims.
So what your saying doesn't surprise me in the least.
C4
Short story for you. BCM was noticing that their GB's were not being held to the correct sizes (.740 and .625). So they ordered them slightly oversized and hand hone them to the correct dims.
So what your saying doesn't surprise me in the least.
C4
Thanks for that summary, that's interesting.
So how does one fix this??
Thanks for that summary, that's interesting.
So how does one fix this??
Measure the barrel and the GB and double check each part and then contact the manufacturer.
C4
Measure the barrel and the GB and double check each part and then contact the manufacturer.
C4
I guess it's time for me to buy some calipers, I've been needing them anyways.
Thanks for the help, let's hope there are no more spec issues in the build.
You can get away with a decent 30-40 dollar set of calipers. I have one, and it's within .001".. enough to tell you which part isn't right.
My money is on the barrel... Seekins has jumped into the AR realm... and their forged lowers have been less than perfect for sure.
simple solution is the clamp version of the slr sentry 7. locktite and paint mark machine screws, done.
"The gas block is a set screw block, will it tighten up at the port when I tighten these down"
Yes. I am not making excuses for out of spec parts but the screw pull the block down tight to the barrel. I wouldn't fool with lock-tite. 500 degrees and it's history. If the screws are flush or below the block stake them.
simple solution is the clamp version of the slr sentry 7. locktite and paint mark machine screws, done.
I have had a lot of issues with clamp style GB's and no longer use them.
YMMV.
C4
"The gas block is a set screw block, will it tighten up at the port when I tighten these down"
Yes. I am not making excuses for out of spec parts but the screw pull the block down tight to the barrel. I wouldn't fool with lock-tite. 500 degrees and it's history. If the screws are flush or below the block stake them.
Green loctite works well. I would argue that I could green loctite a GB (read no set screws or pins) and it would never move. How do I know? Once in a while I have the mis-fortune of having to remove a GB that I installed. :(
C4
"The gas block is a set screw block, will it tighten up at the port when I tighten these down"
Yes. I am not making excuses for out of spec parts but the screw pull the block down tight to the barrel. I wouldn't fool with lock-tite. 500 degrees and it's history. If the screws are flush or below the block stake them.
It still shouldn't be as loose as he is stating it to be. I wouldn't be comfortable with it.
It still shouldn't be as loose as he is stating it to be. I wouldn't be comfortable with it.
This is how I am feeling, unless the unease is misplaced. I'd love to simply use this block and barrel without calling anyone or getting any refunds, but not at the expense of my rifle.
Should I stake it or not?? I could use green loctite too if need be
Thanks guys
Edit: I'm not feeling a ridiculous amount of wiggle when I move it back and forth, very little actually. But just the fact that I can feel any isn't much good. I'm used to having to almost struggle to get a GB onto the barrel.
BufordTJustice
09-11-14, 19:51
I found that the SLR Sentry 7 actually fit very tightly on my Rainier Arms CHF Mountain series barrel. I'm a strong guy and it nearly took a mallet (but not quite).
As I understand it, RA has their CHF barrels made under contact by FN.
I found that the SLR Sentry 7 actually fit very tightly on my Rainier Arms CHF Mountain series barrel. I'm a strong guy and it nearly took a mallet (but not quite).
As I understand it, RA has their CHF barrels made under contact by FN.
I went with the Seekins because I'd heard good things about their barrels, and it's one of the few 8" barrels for a .300 blk that I'd consider.
(I've used their stuff on other builds)
I'm still unsure of where the problem is, I'll take the new calipers to them when they come in. I also plan on having my GB pinned, and would do it myself if I had the drill press.
+1 that set screw GB will seal well enough to run. had a Larue that rattled around on a BCM barrel, just cranked it down with red Loctite . sold the barrel to my brother, still no problems what so ever. for calipers there's a bunch of choices for inexpensive digital calipers either from Brownells or midwayusa. Frankford arsenal work decently but eat batteries pretty quick
Green loctite works well. I would argue that I could green loctite a GB (read no set screws or pins) and it would never move. How do I know? Once in a while I have the mis-fortune of having to remove a GB that I installed. :(
C4
Yes it does, I had red on my G19 front sight and after a year it loosened, took it off, cleaned and gobbed green on it. If I ever have to replace it, I have pliers. Also have used green on a set screw fronts and zero movement.
Yes it does, I had red on my G19 front sight and after a year it loosened, took it off, cleaned and gobbed green on it. If I ever have to replace it, I have pliers. Also have used green on a set screw fronts and zero movement.
Ya, I have had many a Glock front sight come loose with red loctite.
C4
You can get away with a decent 30-40 dollar set of calipers. I have one, and it's within .001".. enough to tell you which part isn't right.
My money is on the barrel... Seekins has jumped into the AR realm... and their forged lowers have been less than perfect for sure.
Please elaborate markm, I'm running three Seekins forged lowers and all have been 100% perfect. I did a Google search and could turn up nothing.
OP: I would check the gas port size, use a small rod or punch to make sure that the gas port and set screws are aligned, and if everything else matches up, you should be good to go. You may want to shim the gas block a bit if it bothers you. As Grant and others have pointed out - green loctite or even staking the screws would probably be a good idea. If you go the loc-tite route, you should be sure to have a dremel in your toolkit in case you ever want to change the GB out and strip your set screws.
Please elaborate markm, I'm running three Seekins forged lowers and all have been 100% perfect. I did a Google search and could turn up nothing.
Magwells were tight on many of them. They did repairs on these for people. I didn't send mine in because their repair was pretty crappy... file and paint it from what I saw. Also the buffer detent holes aren't right on mine. The RE will just barely hold the detent down. I can also turn the RE another full rotation, but then it's too far into the receiver.
Little stuff that irritates me... and why I'm very picky about selecting a stripped lower anymore.
Interesting... I must have gotten mine from a different batch... My Seekins forged lowers actually drop mags better than any of my others.
That is strange. I was under the impression that they were very high quality. I did a build a little while ago using one of their proprietary uppers and the keymod rail to go with, and it's a great set up.
But I agree with you markm about the little things.....
Nothing really gets me more than an out of spec part that causes issue.
Sort of like another build I did forever ago that I'm trying to fix right now, I just can't isolate the issue.
I think in the end, I'll try keeping the barrel and the GB because a couple of you guys recommended it. I'll pick up some green loctite to go with.
OP: its hard to say without having your parts in hand, but the set screw should tighten it down. I prefer the clamp on blocks.
As Grant and others have pointed out - green loctite or even staking the screws would probably be a good idea. If you go the loc-tite route, you should be sure to have a dremel in your toolkit in case you ever want to change the GB out and strip your set screws.
Green Loctite isn't used on the screws, it's used between the gas block and barrel. Loctite also makes a primer that's applied before the green Loctite
Green Loctite isn't used on the screws, it's used between the gas block and barrel. Loctite also makes a primer that's applied before the green Loctite
Is there a particular reason not to use it on the screws, but on the GB instead??
Green Loctite has the added feature of being a wicking threadlocker and is best used on parts that are pressed together or have a close fit. It will wick to coat the entire surface and fill in the nooks and crannies. It can be used on screws, but it's a medium to high strength thread locker. Combine that with it's wicking properties (it will flow to coat the whole of the threads) and you'll have screws that are particularly hard to remove. You don't want to use a thread locker that makes it impossible to remove the fasteners without damaging them. You just want to keep a properly installed fastener from vibrating loose. That's why blue Loctite is a better choice for firearms than red.
It's also why anti-seize is sometimes a better choice than using an anaerobic adhesive (which is what Loctite threadlocker is). The anti-seize reduces the stiction between the threads so a true torque can be achieved while protecting the mating surfaces from corrosion.
If installing the gas block with Loctite, use green between the block and barrel and either stake the set screws, or install them with purple or blue Locktite
Does the green loctite not burn out from the hot gases?
What about this stuff?
http://www.amazon.com/Permatex-81878-Maximum-Temperature-Silicone/dp/B0002UEOPA/ref=sr_1_6?ie=UTF8&qid=1410552143&sr=8-6&keywords=high+temp+adhesive
Clamp on blocks are not nearly as secure and I have seen the clamping screws break.
OP: its hard to say without having your parts in hand, but the set screw should tighten it down. I prefer the clamp on blocks.
This is pretty simple. Either the barrel is not to spec, or the gas block is not to spec. So something needs to go. I use 3 different gas blocks on most everything I build. Geissele, BCM or Sadlak. In almost every case there is a little resistance during installation. When I doubt, I will use Loctite 609 under the block. The barrel is always dimpled and the screws get Loctite 271. Once it cures, the weapon is test fired.
Clamp on blocks are not nearly as secure and I have seen the clamping screws break.
That may be true, but I have never had either come loose. As stated, I prefer the clamp on.
Notice I didn't say come loose. I said screws break. In any case it is not as secure as a dimpled barrel with set screws put together correctly.
That may be true, but I have never had either come loose. As stated, I prefer the clamp on.
Notice I didn't say come loose. I said screws break. In any case it is not as secure as a dimpled barrel with set screws put together correctly.
Actually, you didnt SAY anything. What you typed was that the clamp ons werent "nearly as secure AND I have seen the clamping screws break." I apologize for assuming that not "nearly as secure" meant that they came loose. I would assume that if the screws broke, the block would come loose. I havent experienced any screws breaking either. I understand that you like the set screw blocks. I still prefer the clamp ons.
I see you want to be obstinate. Got it.
Actually, you didnt SAY anything. What you typed was that the clamp ons werent "nearly as secure AND I have seen the clamping screws break." I apologize for assuming that not "nearly as secure" meant that they came loose. I would assume that if the screws broke, the block would come loose. I havent experienced any screws breaking either. I understand that you like the set screw blocks. I still prefer the clamp ons.
JBecker 72
09-12-14, 23:42
What specifically makes you prefer the clamp on gas block? They typically don't have the best track record compared to other attachment methods.
Heavy Metal
09-13-14, 00:43
Green Loctite has the added feature of being a wicking threadlocker and is best used on parts that are pressed together or have a close fit. It will wick to coat the entire surface and fill in the nooks and crannies. It can be used on screws, but it's a medium to high strength thread locker. Combine that with it's wicking properties (it will flow to coat the whole of the threads) and you'll have screws that are particularly hard to remove. You don't want to use a thread locker that makes it impossible to remove the fasteners without damaging them. You just want to keep a properly installed fastener from vibrating loose. That's why blue Loctite is a better choice for firearms than red.
It's also why anti-seize is sometimes a better choice than using an anaerobic adhesive (which is what Loctite threadlocker is). The anti-seize reduces the stiction between the threads so a true torque can be achieved while protecting the mating surfaces from corrosion.
If installing the gas block with Loctite, use green between the block and barrel and either stake the set screws, or install them with purple or blue Locktite
There are two types of green Loctite. One is permanent and high-temp, the other is the med strength wicking.
There are two types of green Loctite. One is permanent and high-temp, the other is the med strength wicking.
Loctite 290 (Green)
https://tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/3184021E8BB54341882571870000D626/$File/290-EN.pdf
Loctite 294 (Green)
https://tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/CD64A4E5A766C9BE882571870000D627/$File/294-EN.pdf
How To Application Guide
http://datasheet.octopart.com/26221-Loctite-datasheet-61062.pdf
This is pretty simple. Either the barrel is not to spec, or the gas block is not to spec. So something needs to go. I use 3 different gas blocks on most everything I build. Geissele, BCM or Sadlak. In almost every case there is a little resistance during installation. When I doubt, I will use Loctite 609 under the block. The barrel is always dimpled and the screws get Loctite 271. Once it cures, the weapon is test fired.
Could I try this using the loose GB and then fire it until I become confident that it is secure, or would you recommend calling a manufacturer and getting sorted?
I'm leaning towards the former
Personally I would attempt to discover the problem and address it. The first place I would start is to try and locate some other gas blocks to see how they fit. Of course, one could measure the barrel and the block (and then ask the respective companies) what their specs are supposed to be.
Could I try this using the loose GB and then fire it until I become confident that it is secure, or would you recommend calling a manufacturer and getting sorted?
I'm leaning towards the former
I have had a lot of issues with clamp style GB's and no longer use them.
YMMV.
C4What sort of problems? Broken bolts like Iraqgunz?
http://www.militarymorons.com/weapons/ar.optics2.html#torque I was linked to that when I questioned clamp on at one point.
If people have only seen problems on other peoples guns, it's entirely possible that they didn't get the barrel and FSB clean enough first.
I'm relatively new to ARs. I have a 5.45 gun with a Ballistic Advantage barrel and a lopro block of unknown brand, set screw style. It's fairly tight, I ended up using a small dead blow to get it in place. However, I end up with significant powder residue in the area. Is that most likely the gas block or the tube? I've been considering picking up a V7 Ti gas block, don't really see any downsides other than that it lightens my wallet more than my gun.
What sort of problems? Broken bolts like Iraqgunz?
http://www.militarymorons.com/weapons/ar.optics2.html#torque I was linked to that when I questioned clamp on at one point.
If people have only seen problems on other peoples guns, it's entirely possible that they didn't get the barrel and FSB clean enough first.
I'm relatively new to ARs. I have a 5.45 gun with a Ballistic Advantage barrel and a lopro block of unknown brand, set screw style. It's fairly tight, I ended up using a small dead blow to get it in place. However, I end up with significant powder residue in the area. Is that most likely the gas block or the tube? I've been considering picking up a V7 Ti gas block, don't really see any downsides other than that it lightens my wallet more than my gun.
I have seen broken screws from over torquing or from poor quality screws. My main issue came when something was out of spec (either barrel wasn't at .750 or the GB wasn't at .750). The clamp would tighten down and give the illusion that it was on the barrel, but in reality, it wasn't. After so many rounds, they would typically move just slightly (and you would lose gas pressure). I have never had this issue with a set screw GB (barrel dimpled) even if something was out of spec.
I guess in a perfect world where the barrel was exactly at .750 and the GB was honed to that size as well, it would work. Note that BCM does not make a clamp on GB. Clue? Not fully sure.
In your instance, my guess is that it isn't aligned properly (didn't put the correct space between the GB and the barrel shoulder)? For me, there is a only ONE GB I will use on my personal guns (as I know how they make them).
YMMV.
C4
I used .040 worth of feeler gauges to space it out, but I wouldn't expect being right at the shoulder to cause a gas leak. Then again, that's me talking out of my ass.
What brand GB do you like? Have you tried the V7 ones?
I used .040 worth of feeler gauges to space it out, but I wouldn't expect being right at the shoulder to cause a gas leak. Then again, that's me talking out of my ass.
What brand GB do you like? Have you tried the V7 ones?
Ya, it can as the gas has no where to go. The clue is that it either covers the GT or GB.
C4
I have seen broken screws from over torquing or from poor quality screws. My main issue came when something was out of spec (either barrel wasn't at .750 or the GB wasn't at .750). The clamp would tighten down and give the illusion that it was on the barrel, but in reality, it wasn't
These are known problems with clamping parts and not just with gas blocks. Screws stretch and break, the clamp will stretch, the hole the screw passes through will either wear or stretch at the wall. Clamps can be useful when designed, made right and installed right, but they can be very problematic
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