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I was reading a post where SOCOM42 stated that the Brookfield Precision Tool gas piston -2 would stop the blowback of gas with a suppressor.(see linked thread below) What is technically different about this gas piston compared to a Sadlak or USGI piston that it is able to do this? (For what it is worth I noted that SEI has a new “patent pending” gas piston that is supposed to be designed for suppressor use) I am curious because I have followed the XM25 build threads for a long time and I always see mention of the -1 and -2 gas pistons and I never understood “why” they were different until I read SOCOM42’s post. Now I am curious about “what” is different between them.


For what it is worth, it is unfortunate that SOCOM42 is not posting on the site anymore because I would just ask him to clarify. I read through a lot of his old posts and I liked his simple and direct approach to questions.
 

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I was reading a post where SOCOM42 stated that the Brookfield Precision Tool gas piston -2 would stop the blowback of gas with a suppressor.(see linked thread below) What is technically different about this gas piston compared to a Sadlak or USGI piston that it is able to do this? (For what it is worth I noted that SEI has a new “patent pending” gas piston that is supposed to be designed for suppressor use) I am curious because I have followed the XM25 build threads for a long time and I always see mention of the -1 and -2 gas pistons and I never understood “why” they were different until I read SOCOM42’s post. Now I am curious about “what” is different between them.


For what it is worth, it is unfortunate that SOCOM42 is not posting on the site anymore because I would just ask him to clarify. I read through a lot of his old posts and I liked his simple and direct approach to questions.
Read the entire conversation that you linked to, the piston didn't help the original poster with his blowback issue.
 

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Discussion Starter · #8 ·
Read the entire conversation that you linked to, the piston didn't help the original poster with his blowback issue.
Thanks. While it was interesting, I was not so interested in the original posters problem. It could be several things and as you say it was some other reason than the piston. I was interested to see the mention of the purpose of the BPT -2 gas piston. This forum has been great in giving that knowledge and again proves to be fantastic. I have not seen a piston specifically mentioned for sale in the market now as a suppressor rated gas piston. I am surprised that Sadlak doesn’t market one given the increasing popularity of suppressors.
 

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Thanks. While it was interesting, I was not so interested in the original posters problem. It could be several things and as you say it was some other reason than the piston. I was interested to see the mention of the purpose of the BPT -2 gas piston. This forum has been great in giving that knowledge and again proves to be fantastic. I have not seen a piston specifically mentioned for sale in the market now as a suppressor rated gas piston. I am surprised that Sadlak doesn’t market one given the increasing popularity of suppressors.
There are just too many barrel and suppressor combos too keep track with what works and what doesn’t.
 

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What do people do when they want to run a suppressor? Do they make a custom gas piston to ensure proper functioning or do they just accept poor performance of the system?
Rev-2 pistons are collector items, the smart guys (including myself) drill the off side of the spindle valve with a smaller hole and work up until the rifle functions regardless of the barrel and suppressor or load combo. Remove the can, turn the spindle valve too the full open position and bang away, slide the can on and twist the spindle too the reduced position.
 

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Rev-2 pistons are collector items, the smart guys (including myself) drill the off side of the spindle valve with a smaller hole and work up until the rifle functions regardless of the barrel and suppressor or load combo. Remove the can, turn the spindle valve too the full open position and bang away, slide the can on and twist the spindle too the reduced position.
And those of us smart enough to know that we can’t be trusted to do that sort of work can buy the modified spindle valves from Art at shootingsight.
 

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Discussion Starter · #14 ·
Rev-2 pistons are collector items, the smart guys (including myself) drill the off side of the spindle valve with a smaller hole and work up until the rifle functions regardless of the barrel and suppressor or load combo. Remove the can, turn the spindle valve too the full open position and bang away, slide the can on and twist the spindle too the reduced position.
Everyone seems to agree that next to bedding that unitizing the gas cylinder is the biggest improvement in precision of the rifle system. From my reading on this forum it also seems to be a consensus that the “screw and glue“ method of unitizing is the preferred method with even some armorers saying they won’t unitize with welding. The XM25 from my reading utilized the welding process for unitizing. Does this mean the the “screw and glue” unitizing precludes the occasional use of a suppressor?
 

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I agree on the importance of the unitizing of the gas system. I have been using the weld method on dozens of my rifles. May be a bit crude in the eyes of some perfectionists, but function is the same. Haven't had one of my farmer's welds break as of yet.
As far as suppressors and back blasts go, this is very easy to overcome. I use OSS HX-QD Ti suppressors on all lengths of my M14s and ARs from 16.5" to the full 22" with no significant smoke in the face or the need to make any modifications to the rifle. They just work. I stopped using the old fashioned suppressors years ago when OSS came out with their forward venting units. Whatta Hobby!




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from 16.5" to the full 22" with no significant smoke in the face or the need to make any modifications to the rifle. They just work. I stopped using the old fashioned suppressors years ago when OSS came out with their forward venting units. Whatta Hobby!



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Everyone seems to agree that next to bedding that unitizing the gas cylinder is the biggest improvement in precision of the rifle system
Actually the quality of the barrel is often the top slot in my opinion. Those other mods ensure accuracy by providing a consistent platform for the barrel to operate from, but without a good barrel, it’s kind of a waste to tweak the rifle. I would also offer a nice 4.5 lb trigger job in the top 4 or 5 slots.

The AMU style drill-tap-screw method renders the gas spindle inoperable. The screws are typically threaded into the spindle part, so one can not use the spindle valve modification with an AMU type unitized gas cylinders. (US Army M21 sniper rifles therefore couldn’t fire rifle-launched grenades, but that was acceptable).
 

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Rev-2 pistons are collector items, the smart guys (including myself) drill the off side of the spindle valve with a smaller hole and work up until the rifle functions regardless of the barrel and suppressor or load combo. Remove the can, turn the spindle valve too the full open position and bang away, slide the can on and twist the spindle too the reduced position.
I'm looking at this as an option. Do you have any more on specifics using the modified spindle valve? Op rod speed? Ejection pattern? Blow back with the suppressor attached?
 

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I'm looking at this as an option. Do you have any more on specifics using the modified spindle valve? Op rod speed? Ejection pattern? Blow back with the suppressor attached?
I don’t have a can so I can only give you a best guesstimate….. Op-rod speed would only be slowed or delayed as the gas cylinder is getting a reduced amount of gas, after all it is now restricted at the spindle and load depending. This would increase can pressure a slight amount making blow back a little higher as the gas cylinder and the can, can only vent so much gas so fast.

Personally, I would also include a grooved piston as well as the later M-25‘s gas cylinder vent mod for some continuous and additional pressure reduction, this would also aid blow back on the shooter but not eliminate it. Suppressed guns also run filthy, this mod would also knock down piston crud buildup.

Ejection, as long as the case cleared the action and picked up the next round from the mag I would be happy as a clam. But I don’t see fired cases flying off into the stratosphere.

FYI, I use my mod spindle valve for shooting heavy off book loads for Long Range.
 

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I tried to get Sadlak to either make some copies of the rev.2 bpt pistons, or even make me some gas pistons without the gas port drilled. They were not interested. This just leaves the diy method of welding up the gas port and re drilling it to the desired size. Sadly, i do not have a welder or the skills to do fine, precise welding and then cleaning it up. The gas valve mod seems like a good answer. An adjustable gas cylinder for the m14 with 6 or so settings would be the cat's meow. Maybe Art at shooting sight will tackle this?
 

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An adjustable gas cylinder for the m14 with 6 or so settings would be the cat's meow. Maybe Art at shooting sight will tackle this?
Art can drill spindles any size you like but there just isn’t enough area for more than two passages in it, this is a M14/M1A not a FAL. I think Art does make a adjustable too play around with I would go that direction find out what works best for your set up using your best load combo and then having a dedicated spindle made for it.

Only you can decide if the juice is worth the squeeze, I’m just talking out loud here a giving the direction I would head in if I were in this situation.
 
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