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Posted: 6/28/2013 10:32:32 PM EDT
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I'm switching out my FSB for a BTE micro gas block. Since I'm not running a handguard cap does someone make a spacer, or is there a trick to getting the right amount of space to line up the gas block?
Also any tips for lining up a clamp on gas block? Thanks! |
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I'm switching out my FSB for a BTE micro gas block. Since I'm not running a handguard cap does someone make a spacer, or is there a trick to getting the right amount of space to line up the gas block? Also any tips for lining up a clamp on gas block? Thanks! When I got my ARMS 41B-L folding FSB/gas block, it came with a spacer. Not sure if these are common. A video I saw (he made one in that case) said it was either .024" or .025" I think. I'd initially thought of using a feeler gauge. |
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I'm switching out my FSB for a BTE micro gas block. Since I'm not running a handguard cap does someone make a spacer, or is there a trick to getting the right amount of space to line up the gas block? Also any tips for lining up a clamp on gas block? Thanks! When I got my ARMS 41B-L folding FSB/gas block, it came with a spacer. Not sure if these are common. A video I saw (he made one in that case) said it was either .024" or .025" I think. I'd initially thought of using a feeler gauge. I use a pencil to marke the center of the gas port in relation to the back side of the gas block where it meets up to the barrel shoulder. I mark the barrel shoulder at the center mark of the gas port and then align the two ref marks when I install the gas block. As for the postion of the block in relation to the shoulder of the barrel, I use a cheap HarborFreight Micrometer to measure the depth of the center of the gas port and use that measurement to postion the gap at the shoulder. You could also use a small piece of paper and center it on the gas port opening inside the gas block then mark where the gas block ends. That will tell you how far in the gas port is. |
| Feeler gauge would be an easy way to do it but may not be needed. The hole is your gasblock is probably larger than the gas port in the barrel. I've never spaced any of mine and havn't had any problems with being undergassed from a miss aligned gasblock. Guess I could just have been lucky so far. |
| Check out this post: ARFCOM Archive Post. Essentially, your block will show you how far back to mount it. |
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Armalite sells spacers, as long as you have a .750 gas block journal. It's not real obvious when you look at the website to find the part, its just listed as a washer or something. I'll look for it tomorrow. http://www.armalite.com/ItemForm.aspx?item=EU0335 ID = .750" OD = .850" Thickness = .030" |
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I'm switching out my FSB for a BTE micro gas block. Since I'm not running a handguard cap does someone make a spacer, or is there a trick to getting the right amount of space to line up the gas block? Also any tips for lining up a clamp on gas block? Thanks! No need, most lo pro gas blocks are made for that already |
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I'm switching out my FSB for a BTE micro gas block. Since I'm not running a handguard cap does someone make a spacer, or is there a trick to getting the right amount of space to line up the gas block? Also any tips for lining up a clamp on gas block? Thanks! No need, most lo pro gas blocks are made for that already You don't know that until you measure. |
| I had a similar issue when installing my JP adjustable block on my 3Gun build. I put the BCG into the upper with it in the closed position. Then I put my air compressor blowgun down the muzzle and shifted the gas block around until I felt the maximum amount of air blowing through it. |
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Use the LP tool, it will automatically register the block properly regardless of whether it is designed to ride right up to the shoulder or have the gap.
The first setscrew hole is always directly under the gas port on any gas block (that's how they drill the gas port). |
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You could always use a dremel tool to cut a slot on the handgaurd cap you are removing so that you could place the cap between the barrel and the block on assembly and the pull/tap it out once you have the gas block locked down. Lube the modified cap spacer with some gun oil and use a brass hammer.
Wes |
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I'm switching out my FSB for a BTE micro gas block. Since I'm not running a handguard cap does someone make a spacer, or is there a trick to getting the right amount of space to line up the gas block? Also any tips for lining up a clamp on gas block? Thanks! I keep an extra handguard cap around just for checking spacing, also invest in (my opinion) the Rainer gas block dimple tool, easy to use, and really does a great job when it comes to gas block installation. |
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One more question... Gas tube roll pin, any tricks to getting it started? I tried to put it in off the barrel, I tried to put it in on the barrel, no luck. I'm assuming they make some special tool, but can I get by without it? I use roll pin punch starter, then finish with roll pin punch. |
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One more question... Gas tube roll pin, any tricks to getting it started? I tried to put it in off the barrel, I tried to put it in on the barrel, no luck. I'm assuming they make some special tool, but can I get by without it? I use roll pin punch starter, then finish with roll pin punch. This. These are one some of the few tools I consider essential to building. The starters are hollowed out and surround the end of the pin to prevent it from deforming outward while starting. And the roll pin punch itself matches the diameter of the pin, then has a bump or dimple in the center that prevents the pin from collapsing inward when being driven. Mangling a roll pin while driving is one of the pitfalls of trying to "wing it" without the right tools. No fun for anyone there. Much better to have them on hand (while you're at it, a few spare roll pins of the appropriate size is still a good idea). They can be build stoppers if not dealt with properly. |
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So you're saying my build is on hold until I order these. Would you happen to know what sizes I need? Any recommendations? I'm assuming I can't find these locally and I'll have to order them online. Brownells roll pin punch starter, while you are on their website pick up a set of Grace roll pin punches. Those 2 sets of tools are well worth the money and excellent for building. |
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Well,
Ive built many of ar's And I don't own roll pin starters at all...never seen the need... Now I've been driving on roll pins or coil pins for a long time...on many other things than ar's Two things to check...before you buy or even before you try to start a roll pin... 1-is the roll pin bevel there There should be a small bevel on the roll pin where in machining it left a burr and it is taken off usually with a sanding wheel or belt. This leaves a small bevel or lead on the roll pin...if not touch it up... 2-is the hole your going to drive this pin into clean, and it should be free from burr as well...if not touch it up... Well maybe one more...make sure your using the right size roll pin... Given the above I've never used a starte...now I do use the roll pin punches every time... Can't think of a time I ruined a roll pin in many years...and just FYI...never reuse a roll pin... Bret |
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If you dimple your barrel with a dimpling jig, the rear set screw will force the gas block into alignment.
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Plus, secure the FSB or gas block so it doesn't move on you. You can get by starting that pin using a pair of pliers to (lightly) hold the pin while tapping it into the base or block, but that's a lot clumsier. The real biggie is getting the barrel and base or block to stay still while you work, not just not bouncing off the bench, but not moving so that the energy you put into the pin goes in the direction you want it to.
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One more question... Gas tube roll pin, any tricks to getting it started? I tried to put it in off the barrel, I tried to put it in on the barrel, no luck. I'm assuming they make some special tool, but can I get by without it? I use roll pin punch starter, then finish with roll pin punch. |
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Feeler gauge would be an easy way to do it but may not be needed. The hole is your gasblock is probably larger than the gas port in the barrel. I've never spaced any of mine and havn't had any problems with being undergassed from a miss aligned gasblock. Guess I could just have been lucky so far. Agreed. The ports on the low pro style steel gas blocks I have used are large enough that placing it against the shoulder still gives full coverage of the barrel gas port. |
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Feeler gage or Armalite has spacers, if you have access to a laser table cut your own.
Pencil lines on the barrel and block for alignment. Roll pin starter punches are like having a third hand. These threads have a life of their own, obviously you do not need to dimple the barrel for a clamp on. |
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Feeler gauge would be an easy way to do it but may not be needed. The hole is your gasblock is probably larger than the gas port in the barrel. I've never spaced any of mine and havn't had any problems with being undergassed from a miss aligned gasblock. Guess I could just have been lucky so far. Agreed. The ports on the low pro style steel gas blocks I have used are large enough that placing it against the shoulder still gives full coverage of the barrel gas port. This has been my experience as well. I have placed the gas block all the way back and had no issues. In all cases this was with a YHM gas block. I have done the low pro and the one with a flip up front sight built in and one with the clamp on Piccitany gas block. |
| YHM's instructions for their low profile gas blocks call for leaving 1/32" space between the rear of their blocks (except the YHM-9383) and the shoulder on the barrel. They do not mention dimpling for their setscrew blocks, but as you can see, there is some extra work involved in making sure the thing is properly aligned. Dimpling avoids this, and makes positioning the block repeatable. |
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