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Posted: 7/27/2009 6:08:40 AM EST
I bought a micro gas block. It is a super tight fit to get it on my barrel and I am having problems getting it all of the way down to the gas port. Any suggestions on how to handle this? I considered using a dremmel with a sand paper attachment and grinding it down a little. I just don't want to mess up the finish on the barrel if I can help it!
Link Posted: 7/27/2009 7:04:53 AM EST
I'm assuming you've already tried a plastic mallet of some sort?
Link Posted: 7/27/2009 7:14:19 AM EST

I am just a noob but on crankshafts i assemble to get gears on we heat the gear up and slide it on with welders gloves. cools and is tight. Can that be done on gas blocks? Set on hot plate few minutes.
Link Posted: 7/27/2009 8:11:54 AM EST
If you're going to sand anything, sand the gas block, not the barrel. Always modify the cheapest part. Get a set of calipers and check the OD of the barrel and ID of the gas block. If they don't match up then whichever is defective, return it to get it fixed. If they do match up then try one of the above suggestions.
Link Posted: 7/27/2009 8:20:58 AM EST
[Last Edit: 7/27/2009 8:21:30 AM EST by kchustle]
Originally Posted By Primos:
I'm assuming you've already tried a plastic mallet of some sort?


You know what Assume means now don't you?!? I have not tried the mallet simply because of how tiny the gas block is (cmmg micro) and if there was a better way (one that would screw up the finish of the barrel) I would rather try that first. Keep the ideas coming so that I have some options tonight!!

Link Posted: 7/27/2009 10:44:57 AM EST
Originally Posted By kchustle:
Originally Posted By Primos:
I'm assuming you've already tried a plastic mallet of some sort?


You know what Assume means now don't you?!? I have not tried the mallet simply because of how tiny the gas block is (cmmg micro) and if there was a better way (one that would screw up the finish of the barrel) I would rather try that first. Keep the ideas coming so that I have some options tonight!!



It is probably just the finish on the inside of the gas block that is causing the problem. I would take some fine sandpaper and rap a small piece around your pinky finger and insert it inside the gas block and twist. The dremmel may take to much off of one side or the other and then the gas block is not going to fit right. And as posted above I would not sand or grind on the barrel.
Link Posted: 7/27/2009 12:15:13 PM EST
The absolute last thing I would do is grind/sand it.

Along with what Texjames said:
I'd freeze the barrel and heat up the gas block. Many manual transmissions have extremely tight clearances that require this method for installing gears on the mainshafts
Link Posted: 7/27/2009 12:51:02 PM EST
I've only had one gb that had an interference fit. I just used a hair dryer to apply heat. Just make sure the placement is correct.
Link Posted: 7/27/2009 1:27:13 PM EST
[Last Edit: 7/27/2009 1:27:35 PM EST by texjames]
Originally Posted By raw_power:
The absolute last thing I would do is grind/sand it.

Along with what Texjames said:
I'd freeze the barrel and heat up the gas block. Many manual transmissions have extremely tight clearances that require this method for installing gears on the mainshafts

Yeah its amazing how tight they can get when cool and have to be pulled off with a puller but slip right on hot.

Link Posted: 7/29/2009 5:33:56 PM EST
Originally Posted By JoshAston:
If you're going to sand anything, sand the gas block, not the barrel. Always modify the cheapest part. Get a set of calipers and check the OD of the barrel and ID of the gas block. If they don't match up then whichever is defective, return it to get it fixed. If they do match up then try one of the above suggestions.


I am having this same issue on my first build. I am not a machinist by any means and might be slightly off with my measurements but when I checked the gb, one side of the block was .750 and the other .745. The gb would only slide about 1/4" down the barrel. I sent it back to the manufacturer yesterday. Since I am a noob and don't know any better that was my solution. Hopefully it will come back with the correct diameter.

260
Link Posted: 7/30/2009 6:57:02 PM EST
Victory!. I tried cooling the barrel and heating the block but it didn't help. I think that choosing one or the other might be better but I don't have that kind of patience. So, I wrapped a towel around the block and used my channel lockers to grip the block and then spun the block around the barrel like I was threading it on. It took a little work but it eventually made it there. It will officially go bang (repeatedly).
Link Posted: 7/31/2009 1:28:31 AM EST
Originally Posted By kchustle:
Victory!. I tried cooling the barrel and heating the block but it didn't help. I think that choosing one or the other might be better but I don't have that kind of patience. So, I wrapped a towel around the block and used my channel lockers to grip the block and then spun the block around the barrel like I was threading it on. It took a little work but it eventually made it there. It will officially go bang (repeatedly).



Glad you finally got it on there.
Range report needed
Link Posted: 7/31/2009 3:25:52 AM EST
Originally Posted By Gatorhunt:
Originally Posted By kchustle:
Victory!. I tried cooling the barrel and heating the block but it didn't help. I think that choosing one or the other might be better but I don't have that kind of patience. So, I wrapped a towel around the block and used my channel lockers to grip the block and then spun the block around the barrel like I was threading it on. It took a little work but it eventually made it there. It will officially go bang (repeatedly).



Glad you finally got it on there.
Range report needed


Hoping to sight it in this weekend. I will give you an update.

Link Posted: 7/31/2009 6:10:50 AM EST
I use a 100 watt light bulb in a trouble light to heat up bearings and gas blocks if needed.
Link Posted: 8/3/2009 9:42:32 AM EST
Originally Posted By comp1911:
I use a 100 watt light bulb in a trouble light to heat up bearings and gas blocks if needed.


I used my wife's hair dryer. That didn't go over well. Apparently it is really expensive and it had be on for 15 minutes or so when she heard it.

Didn't do much but sight it in but it ran B E A utifuly (not breaking out the rulers for group sizes because any poor performance would be me and not the gun but I was happy with how it went). Mission Frankenkiller complete. Now to actually do some real practice at the farm!!
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