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

[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.

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.

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.



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.