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12/6/2019 7:27:02 PM
Posted: 12/15/2016 6:25:34 PM EST
How do I know which diameter gas block I need? Looking to replace a mid length hand guard on a del-ton mid length upper with a keymod rail. I will have to remove the front sight base and need a low profile but not sure how to determine it.
Link Posted: 12/15/2016 6:32:23 PM EST
Link Posted: 12/15/2016 6:35:16 PM EST
Use calipers to measure the barrel immediately in front of the current block/sight base. That should be the gas block diameter required. Most likely .750".
Link Posted: 12/15/2016 6:38:53 PM EST
Thanks! Wasn't sure the right place to get that measurement.
Who makes the best budget friendly keymod? I like the utg, but didn't know if there were other good options at a reasonable price.
Link Posted: 12/16/2016 1:16:06 AM EST
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Originally Posted By Circuits:
Use calipers to measure the barrel immediately in front of the current block/sight base. That should be the gas block diameter required. Most likely .750".
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This. More than likely .750. Just look at your barrel specs.
Link Posted: 12/16/2016 2:23:22 AM EST
If you have any mechanical abilities... don't replace the gas block/A2! That's the most secure gas block there is. If you're mechanically inclined, shave the tower off of the FSB. You'll be left with a twin pinned, SECURE gas block (WAY more secure than any aftermarket gas block... even if it's pinned on with single pin). It's free, there's nothing to align, and it's the best/most rugged set up there is. It boggles my mind how quick people are to replace the A2 FSB for a (inferior) low pro when they already HAVE a more rugged version of it (as said, just shave off the tower). Cost - $0. Benefit - puts any aftermarket low pro gas block to shame. Time - about 15 mins with a dremel.
Link Posted: 12/16/2016 6:54:26 AM EST
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Originally Posted By MaverickAA:
If you have any mechanical abilities... don't replace the gas block/A2! That's the most secure gas block there is. If you're mechanically inclined, shave the tower off of the FSB. You'll be left with a twin pinned, SECURE gas block (WAY more secure than any aftermarket gas block... even if it's pinned on with single pin). It's free, there's nothing to align, and it's the best/most rugged set up there is. It boggles my mind how quick people are to replace the A2 FSB for a (inferior) low pro when they already HAVE a more rugged version of it (as said, just shave off the tower). Cost - $0. Benefit - puts any aftermarket low pro gas block to shame. Time - about 15 mins with a dremel.
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This is what I would do, but you have to find a rail that works with a GI barrel nut. Troy makes a couple because I have one. There are some others. Won't be the cheapest, but you save the money from gas block purchase to put towards it.
Link Posted: 12/16/2016 7:21:23 AM EST
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Originally Posted By MaverickAA:
If you have any mechanical abilities... don't replace the gas block/A2! That's the most secure gas block there is. If you're mechanically inclined, shave the tower off of the FSB. You'll be left with a twin pinned, SECURE gas block (WAY more secure than any aftermarket gas block... even if it's pinned on with single pin). It's free, there's nothing to align, and it's the best/most rugged set up there is. It boggles my mind how quick people are to replace the A2 FSB for a (inferior) low pro when they already HAVE a more rugged version of it (as said, just shave off the tower). Cost - $0. Benefit - puts any aftermarket low pro gas block to shame. Time - about 15 mins with a dremel.
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I purchased a 1-6 scope not thinking of the fsb, but on 6, it's all I can see. So instead of putting this on my go to AR for home defense, I'm going to keep the red dot on it, and install the 1-6 on a different AR, but in order to get the full use of the scope I need to eliminate the front sight base.


Link Posted: 12/16/2016 7:56:49 AM EST
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Originally Posted By cgrubb1:I purchased a 1-6 scope not thinking of the fsb, but on 6, it's all I can see.
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Are you using an especially low mount or something? I just threw a 1-6 on a rifle (rifle gas) and I can see a small shadow at the bottom of the reticle at 3x, at 4x it's gone. You're zooming onto the spot between the ears and at the top of the post so you really shouldn't see anything at all. I just checked it with a midlength and carbine gas system and got the same results.
Link Posted: 12/16/2016 8:54:05 AM EST
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Originally Posted By Keyst0ne:
Are you using an especially low mount or something? I just threw a 1-6 on a rifle (rifle gas) and I can see a small shadow at the bottom of the reticle at 3x, at 4x it's gone. You're zooming onto the spot between the ears and at the top of the post so you really shouldn't see anything at all. I just checked it with a midlength and carbine gas system and got the same results.
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Originally Posted By Keyst0ne:
Originally Posted By cgrubb1:I purchased a 1-6 scope not thinking of the fsb, but on 6, it's all I can see.
Are you using an especially low mount or something? I just threw a 1-6 on a rifle (rifle gas) and I can see a small shadow at the bottom of the reticle at 3x, at 4x it's gone. You're zooming onto the spot between the ears and at the top of the post so you really shouldn't see anything at all. I just checked it with a midlength and carbine gas system and got the same results.


I Used the aero precision ultralight scope mount. The scope is the primary Arms with the ACSS reticle. I can see the center of the reticle pretty well, but the ears of the sight block the bdc marks and ranging feature enough to make it difficult to use
Link Posted: 12/16/2016 9:04:23 AM EST
Really weird, I've never experienced that -- usually it only takes a little magnification to move the focal point of the focus WAY out ahead and anything in the rifle just blurs. Same way you can hold your finger over the lens of a pair of binoculars and still have a dimmer but unobstructed view. Have you adjusted the diopter adjustment in the eyepiece?
Link Posted: 12/16/2016 10:51:35 AM EST
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Originally Posted By Keyst0ne:
Really weird, I've never experienced that -- usually it only takes a little magnification to move the focal point of the focus WAY out ahead and anything in the rifle just blurs. Same way you can hold your finger over the lens of a pair of binoculars and still have a dimmer but unobstructed view. Have you adjusted the diopter adjustment in the eyepiece?
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I will try to get some photos tonight and post them up.
Link Posted: 12/17/2016 2:58:11 AM EST
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Originally Posted By cgrubb1:

I purchased a 1-6 scope not thinking of the fsb, but on 6, it's all I can see. So instead of putting this on my go to AR for home defense, I'm going to keep the red dot on it, and install the 1-6 on a different AR, but in order to get the full use of the scope I need to eliminate the front sight base.
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Anything more than 3x will prevent you from witnessing your front sight (it's optically impossible).
Link Posted: 12/19/2016 2:06:40 PM EST
Typically .750 unless it's a lightweight or pencil barrel. Just an FYI, you can shave your front sight a bit to allow clearance of a new hand guard. Cheap and it works.
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