Need a gunsmith recommendation for drilling a barrel and gas block.

[Bryson]

I have an SLR GB-7 low-pro gas block and a Daniel Defense barrel that DD no longer sells (16" mid-length S2W). The gas block comes with a roll pin, but I'd like to use a taper pin instead. Is there a go-to gunsmith that the M4C hive mind recommends? Need the barrel drilled for both the set screw and the pin, and the gas block has a starter hole where the roll pin goes but needs to be drilled as well (which is why I'm assuming I can convert this to a taper pin).

Thanks.

(Also, if I'm wrong about preferring a taper pin please educate me.)

[GH41]

I have an SLR GB-7 low-pro gas block and a Daniel Defense barrel that DD no longer sells (16" mid-length S2W). The gas block comes with a roll pin, but I'd like to use a taper pin instead. Is there a go-to gunsmith that the M4C hive mind recommends? Need the barrel drilled for both the set screw and the pin, and the gas block has a starter hole where the roll pin goes but needs to be drilled as well (which is why I'm assuming I can convert this to a taper pin).

Thanks.

(Also, if I'm wrong about preferring a taper pin please educate me.)

IMO... I would be comfortable with just the set screw. There are no forces trying to rotate the GB. To me the adjustable GB is more of a liability than the set screw mount. I am assuming the barrel is new and not drilled.

[RobertTheTexan]

I’m on the other side of the fence. I have set screw GB’s but prefer pinned.
Contact Marvin Pitts. He pins GB’s for $45. It sure if your requirements would impact that or not. He’s an awesome barrel guy. He’s an awesome guy.

nefariousarms@live.com

You can also reach him on Facebook. “Nefarious Arms”

[everready73]

John Thomas is the man. Great work and turn around time. Fair pricing. Much preferred to anyone else I have used
http://www.retroarmsworks.com/

[everready73]

If you email him he will get back to you shortly. Was very responsive when I contacted him

[SiGfever]

I have an SLR GB-7 low-pro gas block and a Daniel Defense barrel that DD no longer sells (16" mid-length S2W). The gas block comes with a roll pin, but I'd like to use a taper pin instead. Is there a go-to gunsmith that the M4C hive mind recommends? Need the barrel drilled for both the set screw and the pin, and the gas block has a starter hole where the roll pin goes but needs to be drilled as well (which is why I'm assuming I can convert this to a taper pin).

Thanks.

(Also, if I'm wrong about preferring a taper pin please educate me.)

My correspondence with Criterion Barrels Tech Support told me that they do not recommend using taper or roll pins, just set screws, and the taper pins displace barrel material and both can affect harmonics. Here is a quote from them...

"From: CBI Customer Service
Sent: Monday, May 14, 2018 1:10 PM
To: 'John'
Subject: RE: Enquiry John

John,

I think that you would be very well pleased with one of our chrome lined barrels. In my opinion they are the finest chrome lined barrels available anywhere and our record speaks for itself. We hold numerous National Match titles and world records that were shot with our chrome lined barrels. Head-spacing is essential to obtain optimal timing, function, and performance. An improperly head-spaced barrel/bolt combination results in inconsistent chamber pressures which leads to premature wear on internal components like the extractor and the chamber walls. Inconsistent chamber pressures result in accuracy issues. Head-spacing directly relates to consistent seating depths which aids in accuracy and consistency. Lastly, I do not recommend pinning of the gas block, ever... When you drill a hole through the barrel and the gas block and then drive a taper pin through it, material is displaced. This frequently causes crimping of the bore, harmonics issues, etc. Although this practice has been used by the military for decades, it is something that they are moving away from in order to improve upon their 4 MOA accuracy requirements. As an example here is a recent article about a contract put out by the Marine Corps. Take note of the fourth bullet point under "Required Characteristics", it specifically stated that gas blocks are not to be pinned.

http://www.thefirearmblog.com/blog/2017/05/17/breaking-usmc-releases-rfi-new-infantry-rifles-uppers-optics-suppressors-targets/?utm_source=Newsletter&utm_medium=Email&utm_content=2017-05-20&utm_campaign=Weekly+Newsletter

Working with a number of firearms manufacturers, I have seen issues occur time and time again as a result of this process. I recommend installing your low profile gas blocks with a small amount of thread locker in conjunction with our set screw dimple. If you snug the screws down (being careful not to over torque) to the barrel your gas block will not move until you want to remove it. I have tested this method under sustained full auto fire and have never had a gas block walk off on me... the only thing separating a hobbyist and a professional is knowledge, skill, and experience (something I work on obtaining every day). Let me know if you have any other questions.

Sincerely,

Michael Ross
CBI Technical Support

W172 N13050 Division Rd.
Germantown, WI 53022
Phone: (262) 628-8749
Office Fax: (262) 677-2554"

[Hmac]

I think gas blocks should be pinned rather than relying just on a set screw and some glue (LocTite). It's cheap and easy, even if you don't do it yourself. I've had gas blocks pinned at Ranier, ADCO, from a local gunsmith, and I did one myself with my good old Sears drill press, all with excellent results. It's a very straightforward process and doesn't require much in the way of sophisticated tooling.

[Wake27]

John Thomas is the man. Great work and turn around time. Fair pricing. Much preferred to anyone else I have used
http://www.retroarmsworks.com/

Agreed. OP, I have post on him from a few months ago with some details about my very positive transaction with Retro Arms.

[Clint]

In terms of absolute strength and clamping force, a taper pin is stronger.

But all that force may be too much of a good thing, as mentioned before.

You'll notice the RFI wording.


– Barrel may include low profile gas block but may not use taper pin

No taper pins allowed, but does not say anything about pins in general.


A Coil Pin is a good option here, as the low forces eliminate concerns around bore deflection while offering good security for a low pro gas block.

https://dqzrr9k4bjpzk.cloudfront.net/images/812059/294749816.jpg

[Aetius]

OP,
I had that same barrel pinned by ADCO a few years back. I had two smiths turn down the job. They said the barrel was too hard. I don’t know how true that is, ADCO had no problem with it

[prepare]

In terms of absolute strength and clamping force, a taper pin is stronger.

But all that force may be too much of a good thing, as mentioned before.

You'll notice the RFI wording.



No taper pins allowed, but does not say anything about pins in general.


A Coil Pin is a good option here, as the low forces eliminate concerns around bore deflection while offering good security for a low pro gas block.

https://dqzrr9k4bjpzk.cloudfront.net/images/812059/294749816.jpg

What size coil pin and drill bit do you use?

[markm]

<snip>
Lastly, I do not recommend pinning of the gas block, ever... When you drill a hole through the barrel and the gas block and then drive a taper pin through it, material is displaced. This frequently causes crimping of the bore, harmonics issues, etc. Although this practice has been used by the military for decades, it is something that they are moving away from in order to improve upon their 4 MOA accuracy requirements. As an example here is a recent article about a contract put out by the Marine Corps. Take note of the fourth bullet point under "Required Characteristics", it specifically stated that gas blocks are not to be pinned.
<snip>

Michael Ross
CBI Technical Support

W172 N13050 Division Rd.
Germantown, WI 53022
Phone: (262) 628-8749
Office Fax: (262) 677-2554"

This isn't the first time I've heard/read this. White Oak said this to Pappabear too if I remember right. The BEST pin jobs are reamed to where just half of the ream hole is in the barrel. COLT, BCM, etc. I've seen shit manufacturers where the pin hole is completely in the barrel. WTF?

(Also, I have an ADCO custom cruiser. Their work is American Mediocrity epitomized. Looks like a high school shop student did it)

[556Cliff]

This isn't the first time I've heard/read this. White Oak said this to Pappabear too if I remember right. The BEST pin jobs are reamed to where just half of the ream hole is in the barrel. COLT, BCM, etc. I've seen shit manufacturers where the pin hole is completely in the barrel. WTF?

(Also, I have an ADCO custom cruiser. Their work is American Mediocrity epitomized. Looks like a high school shop student did it)

I remember that old Bushmaster of Maine used to have the taper pin holes completely through the barrels, though I never had any issues with their accuracy. And just recently (maybe not surprisingly) I received a brand new Windham Weaponry 20" A2 profile barrel and I was miffed to see that the taper pin holes were completely through the barrel. Despite this, I believe their barrels are the best of the commercial grade manufacture's barrels. I just wish they would correct this in future runs of barrels because they've corrected a few things since they were Bushmaster.

My preferred barrels are from Colt and Daniel Defense.

[titsonritz]

This isn't the first time I've heard/read this. White Oak said this to Pappabear too if I remember right. The BEST pin jobs are reamed to where just half of the ream hole is in the barrel. COLT, BCM, etc. I've seen shit manufacturers where the pin hole is completely in the barrel. WTF?

(Also, I have an ADCO custom cruiser. Their work is American Mediocrity epitomized. Looks like a high school shop student did it)

I built a GAU-5A using a Criterion was going to pin because I was a little worried about smacking the end of the tube when putting it together but after talking with them I didn't pin.

[markm]

I remember that old Bushmaster of Maine used to have the taper pin holes completely through the barrels, though I never had any issues with their accuracy. And just recently (maybe not surprisingly) I received a brand new Windham Weaponry 20" A2 profile barrel and I was miffed to see that the taper pin holes were completely through the barrel. Despite this, I believe their barrels are the best of the commercial grade manufactures barrels. I just wish they would correct this in future runs of barrels because they've corrected a few things since they were Bushmaster.

I've used those Bushies in the past with decent luck too. I think my m4 barrel had like 80% ream into the barrel.. still too much.

[556Cliff]

I've used those Bushies in the past with decent luck too. I think my m4 barrel had like 80% ream into the barrel.. still too much.

The old ones I had the FSBs off of were more or less the same, sometimes one of the two pins would be about 80% into the barrel and the other was 100% into the barrel. I also believe that this made the taper pins more of a b!tch to remove than the ones drilled more evenly to be about 50% into the barrel

[markm]

The old ones I had the FSBs off of were more or less the same, sometimes one of the two pins would be about 80% into the barrel and the other was 100% into the barrel. I also believe that this made the taper pins more of a b!tch to remove than the ones drilled more evenly to be about 50% into the barrel

Could be, although Colt and BCM which are reamed much better are both tough to remove too.

[titsonritz]

The old ones I had the FSBs off of were more or less the same, sometimes one of the two pins would be about 80% into the barrel and the other was 100% into the barrel. I also believe that this made the taper pins more of a b!tch to remove than the ones drilled more evenly to be about 50% into the barrel

Drifting them in the correct direction helps substantially. :jester:


Could be, although Colt and BCM which are reamed much better are both tough to remove too.

Honestly, I've never had a problem with either one using IG's technique of a barrel vise jaws, large pin punch and 1" hammer.

[Clint]

We use an 1/8" (.125") pin, which is similar in size to a mil-spec taper pin.

What size coil pin and drill bit do you use?

[georgeib]

Drifting them in the correct direction helps substantially. :jester:



Honestly, I've never had a problem with either one using IG's technique of a barrel vise jaws, large pin punch and 1" hammer.

Only one I've had extreme difficulty with is BCM. Tried everything. Finally bought a Wheeler Taper Pin Removal Tool and it got the pins to move.

[556Cliff]

Drifting them in the correct direction helps substantially. :jester:

Lol! Yes that helps quite a bit. :laugh:

[prepare]

We use an 1/8" (.125") pin, which is similar in size to a mil-spec taper pin.

1/8 X 5/8 ?

[rainman]

Drifting them in the correct direction helps substantially. :jester:



Honestly, I've never had a problem with either one using IG's technique of a barrel vise jaws, large pin punch and 1" hammer.

Got a link to that technique? I need to remove a BCM pinned FSB sometime in the next couple of weeks.

Thanks.


-Rainman

[556Cliff]

Got a link to that technique? I need to remove a BCM pinned FSB sometime in the next couple of weeks.

Thanks.


-Rainman

I mentioned the method in this thread. > https://www.ar15.com/forums/AR-15/Need-to-remove-gas-tube-from-A2-sight-before-removing-it-need-to-know-before-trying-it-/4-770624/

If you scroll all the way down, samuse has a picture of how the barrel should be placed in the vise using barrel blocks. It's really the best method.

[georgeib]

Got a link to that technique? I need to remove a BCM pinned FSB sometime in the next couple of weeks.

Thanks.


-Rainman

Easy button: https://www.amazon.com/Wheeler-Tactical-Sporting-Gunsmithing-Maintenance/dp/B07792P951

All you need is a vice and it will press the pins loose, which you can then punch out easily.

[titsonritz]

Got a link to that technique? I need to remove a BCM pinned FSB sometime in the next couple of weeks.

Thanks.


-Rainman

He describes it here, I've done it multiple times and it works like a charm. I just removed a BCM FSB a couple of weeks ago to replace the Magpul MOE handguard with a Centurion Mlok C4 FSB handguard, not a single hitch.

Remove and reinstall front sight? (https://www.m4carbine.net/showthread.php?172822-Remove-and-reinstall-front-sight&highlight=taper)

[rainman]

Thank you both georgeib and ToR for the replies!


-Rainman

[georgeib]

He describes it here, I've done it multiple times and it works like a charm. I just removed a BCM FSB a couple of weeks ago to replace the Magpul MOE handguard with a Centurion Mlok C4 FSB handguard, not a single hitch.

Remove and reinstall front sight? (https://www.m4carbine.net/showthread.php?172822-Remove-and-reinstall-front-sight&highlight=taper)

That's the thread I originally read when I was trying to remove my BCM FSB. It didn't work for me because I think I got one that was a bit "extra." Even after removing the pins and trying to press them back in (the same slots they came out of, and in the correct orientation), I haven't been able to get them all the way in.


Thank you both georgeib and ToR for the replies!


-Rainman

You got it, man! Let us know how it works out for you.

[GunFighter98]

I have used the Triarc easy pin gas block a couple of times. Super easy and then I dont need to send anything off and wait.