View Full Version : Should I pin over set screw?
So I'm at the stage in my build where I am assembling the upper -specifically the gas block.
One of my barrels is a LaRue* Stealth which has three dimples and I have the matching gas block. Beefy.
Should I get this pinned? Thoughts? *sidenote: I am having an multi-month ongoing CS issue with them right now.
Another of my barrels is a Ballistic Advantage Hanson. Comes with a pinned gas block, but no dimples. Should I send it off to have it dimpled?
Lastly, I have a GMR barrel with no dimples or pins. I originally wanted a FSB install, but I can't find someone who will do it because the barrel is nitride'd. Should I dimple & pin? On this one I am using a nitride low-pro Brownell's gas block. Weird set spacing at .415.
What's the thoughts on dimpling? Pinning? Is it a must? - All of these rifles could potentially be duty use.
How can I make sure the gas block is properly aligned without the barrel being dimpled? Can I do any of this work myself -I haven't found anyone in the mid-Michigan area I trust anymore.
Sorry if my thoughts are varied and scattered -ADHD like a mother.
While I'm not the definitive authority on gas blocks, I've not ever seen a properly installed gas block set-screwed under a hand guard come loose. In fact, it's difficult to take off some factory installed gas blocks such as BCM.
I used to pin mine on no matter what; and while it's the most bomb-proof way to install it, it's overkill.
All exposed gas blocks or FSBs need pinned, no exception.
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Thanks for the advice.
A guy I know and whom I trust advised that a pinned gas block would allow less gas to escape than a set screw. I'm not sure if this makes sense to me?
I've never heard such a thing, myself. I don't know how that could be possible. A quick search doesn't come up with anything to verify that.
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Could be your friend is thinking that the pressure from the set screws would pull the block tighter against the barrel contour thus providing a better seal. Don't know if that is true or not, just an idea.
Reference your original post - if the gas block is pinned it does not need to be dimpled, so that BA Hanson barrel should be good to go.
Dimpling the barrel for a gas block is not that difficult. I've posted these instructions for installing a Geissele Super Gas Block several times in the past, they explain the process:
https://geissele.com/media/files/super-gas-block-ai.pdf
You can also by a dimpling jig from SLR Rifleworks: http://slrrifleworks.com/index.php?route=product/product&product_id=579
Use the search function for 'barrel dimpling' and you'll find several threads.
Rayrevolver
09-19-17, 06:30
I believe ADCO will dimple opposite the gas port when installing the GB prior to drilling the pin.
It wasn't long ago that this forum was adamant about pins, but that has softened probably based on BCM performance. I have had a few BCM uppers without pins and no issues.
For me, I had ADCO pin my set screw GB. Belts and suspenders!!!
I've never heard such a thing, myself. I don't know how that could be possible. A quick search doesn't come up with anything to verify that.
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Geissele
Superlative
Ballistic Advantage
Syrac
If you own a drill and bits then just buy a jig and dimple your own barrel, they cost less than $40. I paid $35 for my SLR dimple jig, on one side it lines up on your gas port hole so on the other side the dimples are drilled in the perfect spot.
Geissele
Superlative
Ballistic Advantage
Syrac
Could you explain further?
How important overall is dimpling or pinning?
Also, I might give a shot at ADCO. I'm only an hour and half drive away.
If you own a drill and bits then just buy a jig and dimple your own barrel, they cost less than $40. I paid $35 for my SLR dimple jig, on one side it lines up on your gas port hole so on the other side the dimples are drilled in the perfect spot.
Cool. I need to buy a drill press soon. Either way I would go BRD or SLR.
Renegade04
09-19-17, 10:04
So I'm at the stage in my build where I am assembling the upper -specifically the gas block.
One of my barrels is a LaRue* Stealth which has three dimples and I have the matching gas block. Beefy.
Should I get this pinned? Thoughts? *sidenote: I am having an multi-month ongoing CS issue with them right now.
Another of my barrels is a Ballistic Advantage Hanson. Comes with a pinned gas block, but no dimples. Should I send it off to have it dimpled?
Lastly, I have a GMR barrel with no dimples or pins. I originally wanted a FSB install, but I can't find someone who will do it because the barrel is nitride'd. Should I dimple & pin? On this one I am using a nitride low-pro Brownell's gas block. Weird set spacing at .415.
What's the thoughts on dimpling? Pinning? Is it a must? - All of these rifles could potentially be duty use.
How can I make sure the gas block is properly aligned without the barrel being dimpled? Can I do any of this work myself -I haven't found anyone in the mid-Michigan area I trust anymore.
Sorry if my thoughts are varied and scattered -ADHD like a mother.
On that LaRue Tactical Stealth barrel with their gas block, there is no need to pin it. Just use the supplied Loctite and you are good.
Furthermore, if I was to have the gas block pinned but then change the block to another in the future, would the pin hole size be applicable to other gas blocks?
LookAtYourself
09-19-17, 10:21
i was told by a fairly well respected gunsmith that pinning a low profile gas block is completely unnecessary.
Geissele
Superlative
Ballistic Advantage
Syrac
Any links that have data? Would be an interesting read.
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Ned Christiansen
09-19-17, 11:03
Just my opinion but pinned is better, always. Screws come loose, Loctite makes it less likely but not impossible.
Not saying "if it can come loose it will", but I will say "if it can come loose it might".
The good thing about a lo-pro GB is that it doesn't need to be so elaborate as two tapered pins-- because you don't have a 2 1/2" steel lever (front sight base) to attach. There's no big lever in place to get bumped. many lo-pro GB's will be well protected under the hand guard.
For me the set screws are there to hold it in place while I cross-pin it. A 1/8 or 3/16 split pin is adequate.
jataylor11
09-19-17, 11:09
I pin all mine. Just too easy to do. Granted I dont taper-pin them I just use a coiled stainless roll pin I pick up from BRDEngineering. My go to lo-pro block is the SLR GB7-PIN with a pinning flat already on the block ready to go.
Rainier Extended .750 on a Spikes Optimum Profile Barrel
47536
47537
So if I get a BRD for SLR jig, do I need a drill press or a vise + hand drill?
Also, I emailed Jake Carlson of BRD and asked if it matters which dimpling jig I get if I only intend to drill one dimple -making sure it's the same profile width. He replied, "No sir, all of the jigs do one dimple under the gas port."
jataylor11
09-19-17, 13:22
So if I get a BRD for SLR jig, do I need a drill press or a vise + hand drill?
Ive only used a good drill, bit, vise, NO-MAR vise jaws, low drill speed, patience and some cutting oil.
So if I get a BRD for SLR jig, do I need a drill press or a vise + hand drill?
Also, I emailed Jake Carlson of BRD and asked if it matters which dimpling jig I get if I only intend to drill one dimple -making sure it's the same profile width. He replied, "No sir, all of the jigs do one dimple under the gas port."
Yes, I would use a vice. Lots of dimple jigs out there, I use the SRL because I already had an SRL gas block and my SRL jig does two dimples not just one.
https://www.youtube.com/watch?v=m203m8jMYOk
Wasn't there a thread here a while back where pinning, set screws, and clamp on blocks were compared? I want to say dimpling the barrel had some affect on the bore, where pinned had much less of an affect. I can't remember if the difference was enough to even matter, but I decided to pin the Geissele gas block on my most recent SPR build anyway due in part to the info posted in that thread.
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Anyone stake screws in the gas block? I'm guessing it's a bad idea as I've never heard of anyone doing it.
Or maybe it's just overkill?
Anyone stake screws in the gas block? I'm guessing it's a bad idea as I've never heard of anyone doing it.
Or maybe it's just overkill?
I did on my PSA chf by FN. Got curious about it after reading reviews and found the barrel was not dimpled for a set screw which has been the only thing I have found not so hot with Palmetto State's higher-end parts. So I dimpled where the screw (Or screws...really seems like 2) was digging into the barrel, high temp thread locker, followed by staking the tightened screws with an automatic center punch.
Could you explain further?
How important overall is dimpling or pinning?
Also, I might give a shot at ADCO. I'm only an hour and half drive away.
Did ya read the comment I was replying to?
Anyone stake screws in the gas block? I'm guessing it's a bad idea as I've never heard of anyone doing it.
Or maybe it's just overkill?
I'd prefer a pin over set screws.
I have not had a gasblock that was installed with Rockset loosen. All were dimpled as well.
Have not heard of anyone staking, but it could work.
Did ya read the comment I was replying to?
Yeah. I didn't understand your reply.
SomeOtherGuy
09-19-17, 22:09
One of my barrels is a LaRue* Stealth which has three dimples and I have the matching gas block. Beefy.
Should I get this pinned? Thoughts? *sidenote: I am having an multi-month ongoing CS issue with them right now.
I would trust the Larue setup without much concern.
Another of my barrels is a Ballistic Advantage Hanson. Comes with a pinned gas block, but no dimples. Should I send it off to have it dimpled?
No, entirely pointless, the pin is far stronger.
Lastly, I have a GMR barrel with no dimples or pins. I originally wanted a FSB install, but I can't find someone who will do it because the barrel is nitride'd. Should I dimple & pin? On this one I am using a nitride low-pro Brownell's gas block. Weird set spacing at .415.
I'm amused each time I read that no one will pin on a nitride-treated barrel. All you have to do is grind off the exterior nitride layer with an aluminum oxide wheel, then you're back to the base steel at typical hardness (RC maybe 26-28, nothing super hard). From there you drill and pin as if it's an untreated barrel. I have personally done this on three nitride treated barrels, including a Daniel Defense CHF/nitride S2W. With sharp bits of the right type (cobalt steel or carbide) you could probably drill just fine without the preliminary step of grinding off the nitride layer, but that step eliminates any issue.
If you're going to build regularly I suggest standardizing on one quality type of low-pro gas block. I like the Geissele SGB, but there are some other good options like Black River Tactical. You could also use a common set-screw style block (like YHM or Troy) if you have a jig for drilling the pin-hole or access to a mini-mill.
What's the thoughts on dimpling? Pinning? Is it a must? - All of these rifles could potentially be duty use.
How can I make sure the gas block is properly aligned without the barrel being dimpled? Can I do any of this work myself -I haven't found anyone in the mid-Michigan area I trust anymore.
Set screws seem adequate, but I don't like building something that fails, so I pin my builds if I can't find a barrel like that has a factory pinned gas block - which is pretty easy to do now.
Duty use is a bit of a thread veer, but I don't like the idea of amateur homebuilds for duty use. I would buy a fully assembled quality upper for any on-duty use and keep the personal builds for personal use.
Ned Christiansen is in lower (SW) Michigan and has a great reputation, and he already posted in the thread, but it appears he isn't taking on custom work right now per his website (http://www.m-guns.com/). If you go on MGO forums you should be able to find some other options. There are people in SE Michigan with good reputations who do this work, but I haven't personally used their services so I won't post any names.
Yeah, if I had planned it out better I would have used the same gas block across my rifles. First time building though, so.
I will lurk around the Michigan forum and see what I can shake loose. I also know that I am a new builder, but I have a hard time thinking a factory rifle can be much better than one I can build. Yeah? Out-of-the-box reliability is one thing, but I will def buy a rifle next time. Just would like to see the differences between a factory spec'd rifle and my frankenguns.
Yeah, if I had planned it out better I would have used the same gas block across my rifles. First time building though, so.
I will lurk around the Michigan forum and see what I can shake loose. I also know that I am a new builder, but I have a hard time thinking a factory rifle can be much better than one I can build. Yeah? Out-of-the-box reliability is one thing, but I will def buy a rifle next time. Just would like to see the differences between a factory spec'd rifle and my frankenguns.
Not worth it at all to buy factory, my first was factory built and the rest are all assembled by me. You can easily assemble a factory clone like BCM, DD or Noveske a lot cheaper than buying a complete factory rifle.
My Daniels Defense M4V11PRO I put together for about $500 cheaper than buying a new unfired factory V11PRO, But it has all the same parts. Same for my 16" BCM, found a cheap complete factory lower and then a cheap complete upper and now its all BCM but $400 cheaper than buying new.
I'm amused each time I read that no one will pin on a nitride-treated barrel. All you have to do is grind off the exterior nitride layer with an aluminum oxide wheel, then you're back to the base steel at typical hardness (RC maybe 26-28, nothing super hard). From there you drill and pin as if it's an untreated barrel. I have personally done this on three nitride treated barrels, including a Daniel Defense CHF/nitride S2W. With sharp bits of the right type (cobalt steel or carbide) you could probably drill just fine without the preliminary step of grinding off the nitride layer, but that step eliminates any issue.
Yeah that bug up the asses of some seems to be based on fantasy instead of reality.
https://youtu.be/pyenwL7DSMU
Renegade04
09-20-17, 10:18
Furthermore, if I was to have the gas block pinned but then change the block to another in the future, would the pin hole size be applicable to other gas blocks?
Not necessarily. This is where pinning a gas block becomes an issue. This is where set screw gas blocks have an advantage. As long as they are installed properly, there is not an issue.
Thanks for all the tips, tricks, and advice.
I am def enjoying building these rifles. Buying tools I never had. Learning about the platform. It's great.
We offer the option for pinned gas blocks with our barrels.
I was finally able to get my barrel today and used the SRL dimple jig to line up the spots on my barrel, came out perfect.
Here is a pic of the top were the gas port is in the barrel, the screw sets into the the port hole to make sure its perfectly lined up.
https://farm5.staticflickr.com/4514/37345942242_8eec68f0cb_h.jpg (https://flic.kr/p/YU8HvU)IMG_9005 (https://flic.kr/p/YU8HvU) by hd_rolling (https://www.flickr.com/photos/22585324@N07/), on Flickr
Here is the bottom where the dimples go, two holes. You just drill the first hole and then move the guide bolt to the next hole and drill that one. After I dimpled both and set my gas block on everything lined up perfect.
https://farm5.staticflickr.com/4364/37328542456_1848c3aec3_h.jpg (https://flic.kr/p/YSAxaA)IMG_9004 (https://flic.kr/p/YSAxaA) by hd_rolling (https://www.flickr.com/photos/22585324@N07/), on Flickr
https://farm5.staticflickr.com/4413/37328542126_6da6635508_h.jpg (https://flic.kr/p/YSAx4U)IMG_9006 (https://flic.kr/p/YSAx4U) by hd_rolling (https://www.flickr.com/photos/22585324@N07/), on Flickr
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