dimpling pinned ar barrel

[Glock702]

new to building an AR upper,

How do I install a BA Hanson AR barrel with a pinned gas block? Do I dimple my barrel and remove the gas block to be able to torque the AR barrel to the correct spec, then finally re-install the gas block back onto the barrel to finish?

 

[boom boom]

new to building an AR upper,

How do I install a BA Hanson AR barrel with a pinned gas block? Do I dimple my barrel and remove the gas block to be able to torque the AR barrel to the correct spec, then finally re-install the gas block back onto the barrel to finish?

Not sure about your question.

Did you buy a bare barrel that needs to have the pinned military style (has front sight etc.) gas block installed? Or do you want to pin a low profile gas block on (these have no front sight installed--may have a piccatinny rail for mounting a front sight or be designed to go under a free float handguard) ?

Some of these use set screws only and there is a gas block dimpling tool to help install these. If you have a drill press and the proper vises etc. to hold the barrel secure, also you can make a jig to accomplish this or even drill a gas block and barrel for taper pins or some other pinning method if you wish.

However, precision is needed and some barrels (those with nitride finishes for example) are extremely tough and slick. These are difficult to drill as their surface hardness may be more than a lot of drill bits can handle. Slipping and scarring the barrel, drilling a hole into a barrel or so close as to make the barrel unsafe, etc., damaging the gas block, not having the gas block's gas hole match up with the barrel's gas port, are all problems that can occur. Unless you are skilled in precision use of tooling, probably need to get a jig to do it right the first time. You do not want to risk ruining a premium barrel because you did not have the right tooling.

Brownells (https://www.brownells.com/search/index.htm?k=gas+block+tools&ksubmit=y) , among others, is a good source for such tools and often they have videos of how to use them.

 

[Glock702]

Not sure about your question.

Did you buy a bare barrel that needs to have the pinned military style (has front sight etc.) gas block installed? Or do you want to pin a low profile gas block on (these have no front sight installed--may have a piccatinny rail for mounting a front sight or be designed to go under a free float handguard) ?

Some of these use set screws only and there is a gas block dimpling tool to help install these. If you have a drill press and the proper vises etc. to hold the barrel secure, also you can make a jig to accomplish this or even drill a gas block and barrel for taper pins or some other pinning method if you wish.

However, precision is needed and some barrels (those with nitride finishes for example) are extremely tough and slick. These are difficult to drill as their surface hardness may be more than a lot of drill bits can handle. Slipping and scarring the barrel, drilling a hole into a barrel or so close as to make the barrel unsafe, etc., damaging the gas block, not having the gas block's gas hole match up with the barrel's gas port, are all problems that can occur. Unless you are skilled in precision use of tooling, probably need to get a jig to do it right the first time. You do not want to risk ruining a premium barrel because you did not have the right tooling.

Brownells (https://www.brownells.com/search/index.htm?k=gas+block+tools&ksubmit=y) , among others, is a good source for such tools and often they have videos of how to use them.

thank you for that helpful insight. I was talking about a barrel with a pinned gas block: see link below
https://www.gunsmidwest.com/ballistic-bbl-5-56-16-hanson-w-lpgb-140069

This is my first upper build and instead of buying the jig, I think I will take it to my gunsmith. Do most gunsmith's have a dimpling jig and are fairly good at dimpling barrels (will not damage the barrel or drill too deep)?

 

[boom boom]

thank you for that helpful insight. I was talking about a barrel with a pinned gas block: see link below
https://www.gunsmidwest.com/ballistic-bbl-5-56-16-hanson-w-lpgb-140069

This is my first upper build and instead of buying the jig, I think I will take it to my gunsmith. Do most gunsmith's have a dimpling jig and are fairly good at dimpling barrels (will not damage the barrel or drill too deep)?

If the gas block is already installed, there is no need really to pin the gas block as it uses set screws to attach either from underneath or at the sides. Essentially it is clamped in place by set screws. IF you need to remove it at this time to add the barrel nut etc., simply loosen the screws, place the barrel nut etc. on it, and then reatttach it. If you do figure that you need it pinned, go to a gunsmith as the tooling to do it right and risk of messing up have to be figured into the cost.

It is not tremendously hard to do the dimpling for the barrel set screws but I would recommend a jig for the first time as it makes placement easier. Here is a video about how to dimple a barrel

Here is an example of a tool that helps--https://www.joeboboutfitters.com/SLR-AR-15-Gas-Block-Dimpling-Jig-750-p/slr-dj7.htm made and sold by these folks too, https://slrrifleworks.com/index.php?route=product/category&path=57_129

Here is one by KAK for $25 https://www.kakindustry.com/kak-drill-jig-750

There are some cheaper ones that work better with the softer chrome moly barrels or else you have to change your dimpling screws as they are not up to dimpling nitrided barrels.

Before reinstallation, I would use some marking fluid to indicate the previous position of the gas block to ease reinstall and to provide a check if the gas block moves. Do the same marking on location with the set screws and some use the weaker loctite that is removable with hand tools on the lock screws or stake them so they do not move. After a bit of use, the carbon generally hardens and makes the gas block fairly immovable over time so much so that people complain about removing them. The low profile gas block in the picture is designed for use with a free floating handguard at a length which covers it to prevent you from burning your hands as it can get hot. The free float handguard is also supposed to give superior accuracy fwiw and allow spots to mount accessories.

One of the reasons that the military used pinned gas blocks, among others, is that the bayonet lug is on the gas block and you really do not want that coming loose. The other was to have a fixed front sight location for the iron sights used in the AR series until optics came along.