Pinned gas blocks effect on barrel accuracy/harmonics

[AAMP84]

Came across this post on Criterion's IG page about pinned gas blocks effect on barrel accuracy and harmonics. Curious if this has merit and if so, how much it actually effects accuracy in real world situations.

https://www.instagram.com/p/ByAlJmZg...d=lr3tr2a8q1dz

To pin or not to pin: Pinning the gas block negatively effects barrel harmonics and can result in a tight spot in the bore. When pinning the gas block, a hole is drilled through the gas block and the barrel... a pin is then driven through both. In order for the pin to remain in the barrel, barrel material must be displaced, frequently resulting in a tight spot in the bore which can be felt and measured with mechanical gauges. This increases fouling and bullet deformation resulting in accuracy degradation. Furthermore, barrels are like giant tuning forks that launch bullets… drilling a hole in them and driving a pin through it effects barrel harmonics making them less consistent and therefore less accurate. This practice has been used for years but it is antiquated and detrimental to performance. Recent contracts put out by the military specifically state that this practice should be avoided in an effort to improve accuracy (check out the fourth bullet point under “required Characteristics” in the link below). https://www.thefirearmblog.com/blog/...kly+Newsletter

[themonk]

I have heard .15 MOA. I think the real question is what's the gun used for? If it's for duty use - Mil, LEO, or Civilian there is a reason for the pin. If you are trying to get every little bit out of the gun then it makes sense to sacrifice it.

[Eurodriver]

This was posted here years ago.

Apparently, the dimples can affect it just as much.

https://www.m4carbine.net/showthread...nal-DeflectioN

I shot a 2 MOA target at 996 yards on Saturday with a .223...twice in a row. Under time pressure. With windy gusts.

Guess what didn’t matter?

[mark5pt56]

This was posted here years ago.

Apparently, the dimples can affect it just as much.

https://www.m4carbine.net/showthread...nal-DeflectioN

I shot a 2 MOA target at 996 yards on Saturday with a .223...twice in a row. Under time pressure. With windy gusts.

Guess what didn’t matter?

Well, maybe if you would do 1k it would! haha

I only got out to 627 (MGC) Thursday and was tweaking the 5" plate with the LMT MRP-pinned block

Note it states "taper pin"

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

[Sry0fcr]

Interesting, but I think I'll find something else to worry about. Pinned or dimpled/set screwed serve my practical purposes well enough.

[Clint]

Yes,

The pin type matters.

We generally use spiral coil pins, which have relatively low and consistent radial forces when compared to taper pins.

Note it states "taper pin"

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

[alx01]

Criterion surely knows what they are talking about. It's much easier for the manufacturer to compare different gas block install methods vs an end user. I don't think many people would pin two identical barrels differently just to measure accuracy or have proper tools to do a scientific comparison.

I have one barrel with a pinned (single taper pin) low profile gas block and won't be doing it again.
I'd go with Clint's recommendation and use a coil or c-spring type of pin. They are much easier to install/remove/replace and most 1/8" diameter pins have a shear strength of 1000-2200lb depending on the pin type which is sufficient for any hard use.

Might not use pin at all and just dimple and loctite. I personally doubt I will see much difference either way in practical terms in AR given my skill level.
For me, pinning a gas block using taper or coil pins simply provides more confidence that it was done right.

[ViniVidivici]

This was posted here years ago.

Apparently, the dimples can affect it just as much.

https://www.m4carbine.net/showthread...nal-DeflectioN

I shot a 2 MOA target at 996 yards on Saturday with a .223...twice in a row. Under time pressure. With windy gusts.

Guess what didn’t matter?

Yeah but yer speshul!

I still think the advantages of pinning far outweigh the disadvantages.

Roll pin FTW.

[trauma]

I think when you start critiquing taper pins, you might as well consider barrel profile, chrome lining etc.

I guess if you stay away from chrome lining, avoid taper pins and get a sweet barrel profile all accuracy would improve.

[markm]

I wouldn't think that a correctly reamed taper pin would cause a tight spot. If exactly half the ream is in the barrel it will just pull the block down tight.

Not sure why anyone would taper pin a lo pro block. There's no need for that level of mounting strength. Some of the coil pins that come with the lo pro blocks are so massive, I won't even attempt to remove that much material from a barrel to get in in place. I just set screw them into a dimple.