barrel dimpling?

[BoilerUp]

The dimple is irrelevant to indexing, that's like saying you need the dimple to index.

No, it's not "like" saying that at all. A properly dimpled barrel simplifies indexing a set screw gas block as you simply have to index the rear set screw. Of course, a dimple is useless if you are pinning or using a clamp on gas block.

I do agree that a dimple will improve the mounting of a set screw gas block, but a properly torqued set screw gas block on a non-dimpled barrel isn't going anywhere under normal use and if you've got it tucked under a handguard then you'd have to be doing something pretty weird to knock it out of alignment.

[Axlnut]

A lot of posters are discussing dimples/set screws and taper/straight pins like they are mutually exclusive and that is not the case.

Set screws into a dimpled barrel are far stronger than set screws biting into a non-dimpled barrel, and don't require as much torque on the small fasteners to be effective. I don't want to oversimplify and say it's common sense.. but it is.

A pinned gas block (aside from fixed FSB) in the AR world is typically also dimpled, and this is an area where the MECHANICAL indexing of the set screw becomes hugely beneficial - that's the word missing... mechanical indexing. You can index anything, and hope it stays indexed through the next operations (pinning, etc) but when you mechanically index via a set screw, then set up a rigid fixture for pinning.. nothing can move, life is good. After pinning you can do whatever you want with the set screw, leave it, remove it, etc.

An example that almost everyone knows well where there is no mechanical index prior to pinning: AK platform.

Google search "AK canted fsb" and check how easy they are to get straight with no mechanical index (based off the gas port location).

Dimples and set screws are fine, 1 or 2. Slather everything in loctite and it's likely never going anywhere.

Pinned is fantastic. Pinning without dimples and set screws is a royal PITA to jig up.

No dimples, no pins.. meh. Lazy. The hole is already in the gas block by default, take advantage of it.

[Stone]

No, it's not "like" saying that at all. A properly dimpled barrel simplifies indexing a set screw gas block as you simply have to index the rear set screw. Of course, a dimple is useless if you are pinning or using a clamp on gas block.

I do agree that a dimple will improve the mounting of a set screw gas block, but a properly torqued set screw gas block on a non-dimpled barrel isn't going anywhere under normal use and if you've got it tucked under a handguard then you'd have to be doing something pretty weird to knock it out of alignment.

Agreed, "A properly dimpled barrel simplifies indexing" But the other post said it was "solely for indexing" Implying that indexing couldn't be achieved without dimpling. Which is what I got from reading it. Besides it being a direct contradiction to my original post I felt I needed to defend my statements. Its all good. I think we are, for the most, debating towards the same end result. In my mind I saw a gas block exposed past the rail which kind of tied into my original post which is what I was alluding to. I failed to mention that in the last post. I dimple before pinning as well which holds the block in place so I know nothing will shift while going through the pinning process.

[JoshAston]

Agreed, "A properly dimpled barrel simplifies indexing" But the other post said it was "solely for indexing" Implying that indexing couldn't be achieved without dimpling. Which is what I got from reading it.

I didn't say indexing can't be achieved without dimpling. But the reason for dimpling is most definitely to simplify indexing.

[alamo5000]

Alright alright! It's used for indexing!

My opinion on it is yes that's 100% correct but it does also allow the set screws more territory to bite into. But if those set screws are not loctited or whatever into place repeated fire and recoil (not brute force directly on the block) can rattle those screws loose. Dimple or no dimple if the screws back out the block comes loose.

Everyone though seems to be in agreement that pinning is sure fire though.

[BoilerUp]

Alright alright! It's used for indexing!

My opinion on it is yes that's 100% correct but it does also allow the set screws more territory to bite into. But if those set screws are not loctited or whatever into place repeated fire and recoil (not brute force directly on the block) can rattle those screws loose. Dimple or no dimple if the screws back out the block comes loose.

Everyone though seems to be in agreement that pinning is sure fire though.

Yeah, but do you loctite the cross pin?

[cjd3]

Yeah, but do you loctite the cross pin?

Hell no, Rocksett.

[Stone]

Just arc weld it...

[din]

Not dimpling will get you killed on the streets.

[doubletap]

So I see some barrels offered with the gas block pinned on. Do they come with the gas block attached and you have to knock the pin out, install the barrel nut and out the block back in or do they come with the barrel drilled for the pin and you put the barrel nut on the the gas block and put the pin in?
The reason I ask is because I've read the pins can be a bear to take out.

[BoilerUp]

So I see some barrels offered with the gas block pinned on. Do they come with the gas block attached and you have to knock the pin out, install the barrel nut and out the block back in or do they come with the barrel drilled for the pin and you put the barrel nut on the the gas block and put the pin in?
The reason I ask is because I've read the pins can be a bear to take out.

For BA it comes installed so you have to knock the pin out to remove the block to install the barrel nut. It's not that difficult assuming you have the right tools.

[fledge]

My latest BA barrels did not have the pin installed. It came in a separate bag.


Removing pins is not as difficult as installing. You don't need a starter punch. :)

[BoilerUp]

My latest BA barrels did not have the pin installed. It came in a separate bag.


Removing pins is not as difficult as installing. You don't need a starter punch. :)

They must have gotten tired of getting calls from newbs asking how you get the barrel nut installed on a barrel with a pinned gas block