I love rocksett for set screws. I'll stake my set screws or use rocksett, or BOTH.
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I love rocksett for set screws. I'll stake my set screws or use rocksett, or BOTH.
"You people have too much time on your hands." - scottryan
HMac: Since you don't receive PM's here goes:
As Rayrevolver posted: From what I remember when I first joined M4C in 2006, it was pinned GB and thats it! And then BCM came along without pins and made it work.
As Iraqgunz mentions, the company that he works for, as well as several others, use dimpled and set-screwed gas blocks.
Here's my take:
1. Unless you have a fixture to hold the barrel and gas-block absolutely aligned to mill the roll pin channel, it is necessary to first dimple and then set-screw the gas-block in order to drill the roll pin channel.
2. In terms of production time, in a true manufacturing facility, slapping the assembly into a fixture, boring the channels for the pins, and then using a press to set the pins is probably most cost effective then dimpling and set-screwing.
3. Another alternative would be to spec barrels with the channel for the gas-block roll pin milled. This would add a step to the barrel manufacturing process and, therefore, add cost to the barrel. I know somebody does this because I've purchased several barrels with the channels for gas block roll pins, here is an example: http://www.gmriflebarrel.com/gm-m40-...kout-ar15-1-7/
4. The cost of producing a gas-block held in place by a roll pin would be less expensive than that of producing a gas-block held in place by two set-screws. BUT, aftermarket producers are selling to folks that generally don't have access to to the equipment to install a pinned gas-block, so they produce gas-blocks which the DIY'er can install with a modicum of common sense and simple tools.
5. An assembler that is putting together rifles in the hundreds, rather than the thousands, is probably going to source parts from these suppliers, rather than contract for a run of gas-blocks built to their specs.
So, if you look at the personalities involved, and the advertisers on this site, it is understandable that the bias toward pinned gas-blocks has shifted.
There is no doubted, that a 'properly' installed set-screw gas-block will be robust enough for normal use. Early on in my DIY career I removed an ALG tube which had been installed on a barrel with a dimpled and set-screwed Geissele gas block. I expected the tube to slide off, it didn't. I thought dayum, is it corroded? So I used a hardwood block to tap the tube forward. This initally took more force than I expected, to my embarrassment when the tube slid off I found that I had smeared the end of the rear socket screw used on the m-lok bipod mount installed on the tube. The gas-block hadn't budged.
All that being said, I wore a reserve parachute for over 150 military and civilian jumps, never needed it, didn't think I would, but still wore it. That being said, Geiselle makes their gas-blocks to be screwed and if you want pinned. I'm doing both.
YMMV
Last edited by 26 Inf; 03-09-18 at 13:23.
Owner/Instructor at Semper Paratus Arms
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Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com
Thanks IG, could you please give us your opinion on the correct application of Loctite on set-screw secured gas blocks? You are using Red but only a tiny bit on the dimpled set screw(s) correct?
Does the Red tend to wick and also bond the gas block to the barrel journal?
And how about the Green wicking Loctite? Have you used it and have an opinion on it? Would it be a good choice for those who don't have (or want to) drill dimples for the set screws?
We clean the screws and then apply a small amount to the screw(s) and put them into the block. Both screws receive the Loctite. I am sure there is a little leakage, but we don't bathe them in Loctite.
By green Loctite I am assuming you mean Loctite 609 retaining compound? If so, that has VERY LIMITED applications as it is very difficult to remove anything once applied.
I can't really speak to the efficacy as I do not use it, nor do I recommend the installation without a proper dimple.
Owner/Instructor at Semper Paratus Arms
Facebook: https://www.facebook.com/SemperParatusArms/
Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/
M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141
Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com
Yes, I was referring to Green 609 for cylindrical bonding. There is also Green 620 for even higher temperature applications. This method would be using the wicking properties to bond the whole gas port to the barrel journal, set-screws and all. I noticed that someone else in this thread had a recommendation for Green Loctite but didn't specify which type. He (Outlander Systems) may have been referring to using Green 209 on the set screws only.
Care to comment Outlander Systems?
One of my main complaints to the AP 308 was no dimples on the barrel nor pinned gas block. Through my countless problems with that piece of junk I sent it back and they replaced several parts including the bcg, bolt, barrel and gas block. The bareel was so over gassed I had to install an adjustable gas block and they still did not dimple the barrel, instead... their fix was the green 609. Needless to say it was a bitch to get off.
I would recommend against using locktite 609.
The MK18 cqbr urg built by crane uses colt barrels with the fsb removed, barrel is dimpled and set screw gas block is used. I believe it’s the same for other issued rifles with rails/ lo pro gas blocks.
The uppers I have built with BCM barrels had deep enough dimples that I don’t see the gas block moving without shearing the set screw, which were installed with rockset.
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