AA barrel + Gas Block question - need help

[warp9764]

So I purchased the AA 18" barrel - looks beautiful. I'm planning on using a Sentry7 Titanium adjustable gas block on it. Issue is, it appears that the AA barrel has a slightly smaller diameter (maybe ~0.25mm) in the middle of the gas block landing area on the barrel. You can zoom in on the gas block area to see what I'm talking about:

http://www.shopalexanderarms.com/DIY_Parts_Components-6_5_Grendel_16_Lite_Barrel.html

Measurements of the gas block landing area (total 46mm)
First section - (0.750" barrel diameter) gas port landing = 14mm long
Middle section (~.25mm smaller barrel diameter) = 18mm long
3rd section (0.750" barrel diameter) = 14mm long

Looking at AA's site, their low profile gas block looks to match up perfectly with this "valley" (and is exactly 46mm long):

http://www.shopalexanderarms.com/DIY_Parts_Components-Low-profile_750_Gas_Block_1.html

But the SLR Sentry7 might not:

http://slrrifleworks.com/index.php?route=product/product&path=57_125_169&product_id=496

Has anyone used an adjustable gas block on the AA barrels? Am I just S.O.L. and need to use the AA block (boo!)? Or is there a way to shim the SLR block? Or should I not worry, and the set screw under the gas port will hold it just fine (assuming the other set screw hits the "valley" area cleanly)?

Thanks again for any help/comments!

[Bowhntr6pt]

So I purchased the AA 18" barrel - looks beautiful. I'm planning on using a Sentry7 Titanium adjustable gas block on it. Issue is, it appears that the AA barrel has a slightly smaller diameter (maybe ~0.25mm) in the middle of the gas block landing area on the barrel. You can zoom in on the gas block area to see what I'm talking about:

http://www.shopalexanderarms.com/DIY_Parts_Components-6_5_Grendel_16_Lite_Barrel.html

Looking at AA's site, their low profile gas block looks to match up perfectly with this "valley":

http://www.shopalexanderarms.com/DIY_Parts_Components-Low-profile_750_Gas_Block_1.html

But the SLR Sentry7 might not:

http://slrrifleworks.com/index.php?route=product/product&path=57_125_169&product_id=496

Has anyone used an adjustable gas block on the AA barrels? Am I just S.O.L. and need to use the AA block (boo!)? Or is there a way to shim the SLR block? Or should I not worry, and the set screw under the gas port will hold it just fine (assuming the other set screw hits the "valley" area cleanly)?

Thanks again for any help/comments!

I have the 16" barrel and a Seekins Adj. gas block, fits fine.

[warp9764]

Whew! Thanks, Bowhntr6pt!

[Bigs28]

I have aa barrel and use a syrac adjustable gas block. Np

[rabiddawg]

I have aa barrel and use a syrac adjustable gas block. Np

My 16” is set up like this^

[TKO]

I have a Superlative Arms adjustable gas block on my 16" AA barrel. No issues.

[growling dog]

I also have an 18" AA barrel and used the Midwest Industries low profile non-adjustable gas block. This gas block is 1.8 inches in length and intended to cover the tapered pin holes from the standard AR fixed front site. It has three screws. The middle screw is in the "valley" area. I know you want an adjustable block, but the MI block works good for me. My 18 " AA barrel is accurate. I think any extended length gas block that contacts both "high" areas would work best.

[Redomen]

I built the 16” AA for my wife and used a JP adjustable gas block and I works fine.

[LRRPF52]

I've built several uppers with both the 16" and 18" fluted barrels with that gas journal profile, no issues at all.

To be honest, they run very smoothly as-is. I've used Sadlak low profile gas blocks, and I bedded them with Red Loc-tite after test-fitting.