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Posted: 6/7/2008 8:23:35 AM EDT
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I think PRI and JP Enterprises offer adjustable gas blocks, has anyone used them? Do they offer a complete shut off of the gas system? I'd like to completely seal the gas off when I'm shooting 22LR from a Ceiner kit so I don't have to worry about any gas tube fouling and not have to switch out bolts and run a few mags of 5.56mm. I've been thinking about setting up a 22LR/M193 upper running a 1/12 twist for mostly shooting 22LR but having it be flexible enough to also shoot M193. I'll probably be going with the 16" CMMG 1/12 midlength barrel and a VTAC Handguard system so would like to know which adjustable block would be most ideal as well. Is there an easier system if I just want ON/OFF on the gas system? |
I have the JP one on two of my AR's. It is not a complete shut off system, as I was hoping to have that option. I have no idea about the PRI one. I do think Noveske had developed/was developing an adjustable gas block as well that actually did look like it was off/30%/60%/100% or something like that. I also know that there has been several attempts from different companies to put the adjustment in the tube instead of the block. No idea on success with that either. |
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I had an adjustable gas system on a similar type of 5.56 rifle: a Mini-14. Though it doesn't exactly answer your question of what is available for AR's, on this point I think there is similarity between what can be done with the Mini's adjustable gas system and an AR system. On the Mini, you can turn it all the way down to the point that the cases do not even eject from the rifle, in effect giving you a bolt gun. This is actually handy if you're in a situation where you're sitting at the bench and required to single load (as with certain kinds of matches), or if your range requires it, or if you don't want to throw your brass. One thing to note about adjustable gas systems is they typically affect your point-of-impact. If you can get one with settings that can be indexed, you will want to figure out the ideal settings for your favorite loads, and record those. |
I have experience with JP. JP does not completely shut off the gas. When screwed all the way down, the bolt will still move slightly rearward, not so far as to eject a round or pick up one. I feel the bolt carrier bump. At two revolutions out, from dead bottom, it will cycle the bolt. As I kept shooting, it worked its way back in. I am not a fan of this design. It did not work well for me. This was on a customer's .204 Ruger upper. FAL had the best gas adjustment system. If someone would copy it, it may work for the AR, but why? I have not seen a use for an adjustable gas system. On/Off I can see. Matt and I built several prototypes, and they worked flawlessly (2 moving parts), but we decided that the market was not there to go into production. We shelved our piston design too: worked great, NO accuracy lose, and TWO moving parts (bolt carrier and piston). |
One version is full open, part open, just a little open Second version is full open, half open, off Third version is on - off, low profile. http://www.ar15.com/forums/topic.html?b=3&f=12&t=377518 |
So is there a version for a 5.56mm barrel? |
Thanks for clearing that up Marty... Do you have anymore low profile in .875? I have a buddy that wants one,also I need one in .750... |
Inside diameter of the barrel is not what matters  As long as your barrel has one of the standard ODs (0.625, 0.75, 0.875 and 0.936) we have blocks. We can custom make them as well. |
Which version - three position (version 2) or 2 position (on/off)? I have a limited selection but EMail me and I can get you in contact with Tom who makes these. Tom's contact info should also be in the thread listed above. Feel free to get with him direct. |
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