View Full Version : Adjustable gas blocks
I have an LMT defender 2000 carbine w/ pinned GB, and Troy rail that is my shtf/class/everyday plinker gun. However I have finally come to the conclusion that my first and follow up shots are faster and more accurate w/ lightweight midlength and rifle gas systems compared to the m4 profile/gas system. Plus with my rotator cuffs being torn the lighter and smoother it is, the longer I can shoot it.
So before I replace my barrel w/ a DD or BCM CHF LTWT midlength can anyone tell me about adjustable gas blocks. Is it possible to get the feel and reliability of a midlength gas system with an adjustable gas block? Can I just "dial-it in" and loctite it or is it more for suppressed guns or a POS and I'm way off base?
My thinking is to have an adjustable gas block pinned and have the barrel re-profiled in front of the FSB for about half the money. Reliability is first and foremost, accuracy and speed are my next priorities.
702Shooter
04-15-12, 17:17
I have an LMT defender 2000 carbine w/ pinned GB, and Troy rail that is my shtf/class/everyday plinker gun. However I have finally come to the conclusion that my first and follow up shots are faster and more accurate w/ lightweight midlength and rifle gas systems compared to the m4 profile/gas system. Plus with my rotator cuffs being torn the lighter and smoother it is, the longer I can shoot it.
So before I replace my barrel w/ a DD or BCM CHF LTWT midlength can anyone tell me about adjustable gas blocks. Is it possible to get the feel and reliability of a midlength gas system with an adjustable gas block? Can I just "dial-it in" and loctite it or is it more for suppressed guns or a POS and I'm way off base?
My thinking is to have an adjustable gas block pinned and have the barrel re-profiled in front of the FSB for about half the money. Reliability is first and foremost, accuracy and speed are my next priorities.
An adjustable gas block isn't going to fool the bullet into thinking it's being shot through a mid-length system. A true mid-length will shoot better than a carbine with an adjustable block if for no other reason than the distance from the gas port to the end of the barrel. Better ballistics too.
"An adjustable gas block isn't going to fool the bullet into thinking it's being shot through a mid-length system. A true mid-length will shoot better than a carbine with an adjustable block if for no other reason than the distance from the gas port to the end of the barrel. Better ballistics too."
Wiskey... Tango... Foxtrot...
Ignoring everything stated above and returning to reality reveals that an adjustable gas block can be used to change the recoil impulse by restricting the amount of gas going to the carrier. The gas system employed does absolutely nothing to alter the trajectory of the bullet. If your rifle has a fixed FSB you can replace it with an adjustable JB FSB and dial back some of the gas until you are happy with the result. The carbon from firing a few shots will "lock" the adjustable setscrew in place sans locktite.
everything i have read(no experience)leads me to tell you it is basically for suppressed rifles and will not give you the results you desire.i believe it is simply a on/off switch and the pressure will remain the same.physics would tell me that a full length gas systems would give you your desired results!i hope this helps,but call some barrel manufacturer`s.
So before I replace my barrel w/ a DD or BCM CHF LTWT midlength can anyone tell me about adjustable gas blocks. Is it possible to get the feel and reliability of a midlength gas system with an adjustable gas block? Can I just "dial-it in" and loctite it or is it more for suppressed guns or a POS and I'm way off base?
No, you can't get the feel of a midlength by using an adjustable gas block. You get the feel of a midlength by buying a midlength barrel and installing it, or by buying a midlength upper. An adjustable gas block is a solution looking for a problem for the majority of shooters out there.
Buy a lightweight midlength upper, install it on your lower, and call it good.
An adjustable gas block isn't going to fool the bullet into thinking it's being shot through a mid-length system. A true mid-length will shoot better than a carbine with an adjustable block if for no other reason than the distance from the gas port to the end of the barrel. Better ballistics too.
Huh? :rolleyes:
Care to explain?
Just a FYI to all...
Please continue share your knowledge, but also please remember to remain civil... Just a friendly reminder...
S/F
B
702Shooter
04-15-12, 19:10
Huh? :rolleyes:
Care to explain?
Not really as I'm no pro in that department. I've spent some time researching this topic a bit and made post based on what I've read online and heard from multiple barrel manufacturers.
http://www.03designgroup.com/technotes/carbine-vs-mid-length-gas-system
702Shooter
04-15-12, 19:10
Just a FYI to all...
Please continue share your knowledge, but also please remember to remain civil... Just a friendly reminder...
S/F
B
Didn't know you were a mod here. Nice. :)
See you Tuesday night.
Not really as I'm no pro in that department. I've spent some time researching this topic a bit and made post based on what I've read and heard from multiple barrel manufacturers.
http://www.03designgroup.com/technotes/carbine-vs-mid-length-gas-system
I've read that article too, but it makes no mentioned of a midlength barrel having better ballistics than an equal length carbine barrel. 16" is 16".
And saying that a midlength will shoot "better" than a carbine is a real stretch too. Many people perceive the midlength to have a lighter recoil impulse (myself included), but what a person "feels" and what is actual fact are two very different things.
I'm not trying to attack you, just keep things objective, and not wander into the land of "it feels better to me".
702Shooter
04-15-12, 19:25
I've read that article too, but it makes no mentioned of a midlength barrel having better ballistics than an equal length carbine barrel. 16" is 16".
And saying that a midlength will shoot "better" than a carbine is a real stretch too. Many people perceive the midlength to have a lighter recoil impulse (myself included), but what a person "feels" and what is actual fact are two very different things.
I'm not trying to attack you, just keep things objective, and not wander into the land of "it feels better to me".
Fair enough. I'm just a hobbyist who's still learning.
Here's another thread discussing the topic.
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2323494
I'll research it a little more now that you have me questioning the theory.
Thanks 702Shooter for the interesting reads.
I have never shot through a 14.5" barrel, but from what I'm gathering from the first article it seems that cutting 1.5" off the barrel should give me a little less velocity but about the same recoil as a 16" mid-length.
Did I read that right?
Reliability is first and foremost
Then don't mess with an adjustable gas block.
The only way for most people to know if the adjustment is "reliable" is to shoot it a lot. Don't forget if you make it too close to minimum in the summer there is a good chance it will choke in the winter.
The best method is checking the cyclic rate, but you need an auto lower or high speed camera.
Then don't mess with an adjustable gas block
That is the final word on that then.
But back to the 14.5 carbine gas system vs. 16 in. Midlength. Same recoil or close to it? I have done a lot of reading on here but have never heard this. Sorry to highjack my own thread but did I read that first article by 702shooter correctly?
Robb Jensen
04-17-12, 21:03
Should only be used on "gamer" guns aka 3gun rifles. FWIW on my 3gun rifle I don't use an adjustable gas block but I do use a JP LMOS 6.25oz carrier. Last Friday I was shooting a Warren Tactical target at 15yds that would face me for 2sec and blade away for 4sec from a low ready assuming my reaction time to first shot was was 1 second I was hitting it 7-8 times during the 2 second exposure. This means my split times were .11sec to .125sec I shot 120 rounds this way and had 6 out of the Warren targets A-zone. A timer doesn't work well there because it's an indoor range (NRA Range in FFX VA).
If my reaction time is shorter them my split times are longer but still fast none the less.
But back to the 14.5 carbine gas system vs. 16 in. Midlength.
I can feel the difference, but it's not that much. Do you have a MB or flash hider on it right now?
Right now I have a PWS FSC (Troy comp and A2 prior) but it's definitely coming off. I was beside my wife the other day while she was shooting it and do I need to say more... Comps are too obnoxious for classes and ranges where people are next to you IMO w/limited experience.
I have been doing research lately of FH's and I haven't decided which I'm going to go with. I am leaning more to the closed design like the KX3 because I do take classes and shoot beside other people fairly regularly.
I would want to shoot whatever FH I decide on before pinning it to my barrel.
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