MCFooter Posted August 30, 2009 Share Posted August 30, 2009 (edited) I finally broke down and picked up a new JP light weight stainless bolt carrier JPBC-3 and a new JP bolt kit JPBC-BA and it’s not working as expected. Maybe it just needs breaking in, I hoping someone can say before I trouble JP with it… Basically it needs MORE gas to lock the bolt and carrier back with the new SS carrier than it did with the OEM RRA Bolt and Carrier. BEFORE 20” Heavy Barrel RRA OEM RRA 2 Stage trigger JP BC Comp JP Aluminum Gas Block JPGS-1 (Adjustment 2.5 – 3 turns open) Standard OEM Bolt Standard Rifle Buffer Standard Rifle Spring Plain Jane and has ALWAYS functioned and locked bolt back … NOW 20” Heavy Barrel RRA OEM RRA 2 Stage trigger JP BC Comp JP Aluminum Gas Block JPGS-1 (Adjustment 4.5 – 5 turns open) New SS Bolt Carrier JPBC-3 New JP bolt kit JPBC-BA Modified Standard Rifle Buffer (With 5 Aluminum pieces replacing steel) Standard Rifle Spring I tried swapping several parts but around but it simply seems to want more gas to operate. I can put the old bolt and carrier back in turn the gas back to 2.5-3 and it will lock back. Can anyone confirm this can be expected or is there something I’m missing?? Should I have gotten the polished version?? Thanks, Mike Edited August 30, 2009 by MCFooter Link to comment Share on other sites More sharing options...
el pres Posted August 30, 2009 Share Posted August 30, 2009 (edited) Off the top of my head ?? It needs to run "WET", the thing about oil on your glasses is not an exageration, I run the aluminum carrier, I know what "wet" is. You may also have to get the right JP buffer and spring, not sure what the 5 aluminum pieces equal to. Finally, is it not picking up the next round, it could have too much gas ?? as the increased bolt speed can be faster then the mag spring !! once again, wet, make sure the gas rings are not lined up and that the inside on the carrier is dripping oil !! Also a heavy hammer spring could slow it down too far, what trigger ?? Edited August 30, 2009 by P.Pres Link to comment Share on other sites More sharing options...
smokshwn Posted August 30, 2009 Share Posted August 30, 2009 I don't understand why/if you think that more gas is a bad thing. The carrier/buffer combo you have installed is lighter yet working against the same force of spring. It stands to reason that you will need more gas to move it the same distance. I am making an assumption that you are under the belief that more gas=more recoil, but that would not be the case. With the lighter components you should feel a net reduction in the recoil impulse even though you are running slightly more gas. +1 on making sure the bolt is wet, not just the carrier. You have to remember everything on a JP is right on gnat's ass to spec so at times there is a little break in needed for parts to wear in. Link to comment Share on other sites More sharing options...
MCFooter Posted August 30, 2009 Author Share Posted August 30, 2009 Off the top of my head ?? It needs to run "WET", the thing about oil on your glasses isnot an exageration, I run the aluminum carrier, I know what "wet" is. You may also have to get the right JP buffer and spring, not sure what the 5 aluminum pieces equal to. Finally, is it not picking up the next round, it could have too much gas ?? as the increased bolt speed can be faster then the mag spring !! once again, wet, make sure the gas rings are not lined up and that the inside on the carrier is dripping oil !! Also a heavy hammer spring could slow it down too far, what trigger ?? I was running it wet and checked the gas rings. I also tried backing off on the gas so I dont' think it's too much gas. Swapping the steel for aluminum in the buffer is suppose to make the OEM equal to a JP low mass but I haven't weighed it yet. I did try a friends Tubbs Flat wire type spring but no change. The bolt would come back far enough to strip off the next round and I was able to double tap with it. Trigger is a OEM RRA 2 Stage (which I didn't think about) Thanks for the response.... Link to comment Share on other sites More sharing options...
MCFooter Posted August 30, 2009 Author Share Posted August 30, 2009 I don't understand why/if you think that more gas is a bad thing. The carrier/buffer combo you have installed is lighter yet working against the same force of spring. It stands to reason that you will need more gas to move it the same distance. I am making an assumption that you are under the belief that more gas=more recoil, but that would not be the case. With the lighter components you should feel a net reduction in the recoil impulse even though you are running slightly more gas. +1 on making sure the bolt is wet, not just the carrier. You have to remember everything on a JP is right on gnat's ass to spec so at times there is a little break in needed for parts to wear in. I guess I was just making the assumption that more gas wouldn't be required. Still thinking about the balance of forces part. I will admit it seemed to move a little less when I opened up the gas. Does anyone use a lighter/ modified buffer spring?? Thanks for the reply. Link to comment Share on other sites More sharing options...
smokshwn Posted August 30, 2009 Share Posted August 30, 2009 Nothing to think about on the balance of forces...here it is Force = mass x velocity squared If the force (spring) stays the same and mass (bcg/buffer) decreases then the velocity must go up in order to move the carrier against the spring. That means you will need more gas. Link to comment Share on other sites More sharing options...
Big Bore Posted August 30, 2009 Share Posted August 30, 2009 I finally broke down and picked up a new JP light weight stainless bolt carrier JPBC-3 and a new JP bolt kit JPBC-BA and it’s not working as expected. Maybe it just needs breaking in, I hoping someone can say before I trouble JP with it…Basically it needs MORE gas to lock the bolt and carrier back with the new SS carrier than it did with the OEM RRA Bolt and Carrier. BEFORE 20” Heavy Barrel RRA OEM RRA 2 Stage trigger JP BC Comp JP Aluminum Gas Block JPGS-1 (Adjustment 2.5 – 3 turns open) Standard OEM Bolt Standard Rifle Buffer Standard Rifle Spring Plain Jane and has ALWAYS functioned and locked bolt back … NOW 20” Heavy Barrel RRA OEM RRA 2 Stage trigger JP BC Comp JP Aluminum Gas Block JPGS-1 (Adjustment 4.5 – 5 turns open) New SS Bolt Carrier JPBC-3 New JP bolt kit JPBC-BA Modified Standard Rifle Buffer (With 5 Aluminum pieces replacing steel) Standard Rifle Spring I tried swapping several parts but around but it simply seems to want more gas to operate. I can put the old bolt and carrier back in turn the gas back to 2.5-3 and it will lock back. Can anyone confirm this can be expected or is there something I’m missing?? Should I have gotten the polished version?? Thanks, Mike I run the a 20" Rock River Stainless barrel with the JP aluminum gas block, JP trigger, standard buffer spring, the light weight stainless carrier and the Jp low mass buffer also. But I only run it 3.25 turns open and have no issues with my 69 gr. loads or my 55 gr. loads. What ammo are you running?? Link to comment Share on other sites More sharing options...
bigbrowndog Posted August 30, 2009 Share Posted August 30, 2009 check to see if you are losing gas around your gas block, i realize it was not a problem before but sometimes shit happens when you least expect it. I HAD an aluminum one ONCE and never again, also did you follow the installation instructions and use locktite or not. I would still suspect it even if you did, however why did you buy the JP carrier and not the JP buffer??? As Craig says, do not assume that because the gas block is needng more turns on it that it is defeatng the purpose of the lite carrier. Trapr Link to comment Share on other sites More sharing options...
Sako92S Posted August 31, 2009 Share Posted August 31, 2009 My suggestion is that; change the gas tube to new one and replace that RRA trigger group with JP + speed hammer. My similar problem vanished with changing gas tube to new one. Taisto Link to comment Share on other sites More sharing options...
mpeltier Posted August 31, 2009 Share Posted August 31, 2009 I believe you are a bit too light in the buffer, and the bolt is unlocking a tad too soon and dropping pressure. Replace one or two pieces of aluminum with the original weights and see how it acts. and as others have said make sure it is lubed real good. Link to comment Share on other sites More sharing options...
MCFooter Posted September 1, 2009 Author Share Posted September 1, 2009 I appreciate all the responses so far guys. I guess I don’t really care how much gas it uses my main goals are. 1) Maintain reliability 2) Get the most out of the system 3) See/feel a noticeable improvement To answer a couple of the questions above. I always shoot 62 grain Wolf (I know, I know but it’s cheap) The Gas block was installed as recommended ~4 years ago I didn’t get the JP buffer because of the $50 price difference and this thread which gave me the idea. I was able to confirm today that the modified buffer was 3.04oz per my local Food Lion deli. I have installed the original bolt and carrier with the lighter buffer and been able to cut the gas back to 2.5-3 turns open as it was originally. I think this eliminates the gas block and gas tube in the equation. Smokshwn I agree/understand > Force = mass x velocity squared, related to the spring but why does it take more Gas Force to move a lesser mass carrier ? > Force = Mass x Acceleration I’m not here to argue, I just want to understand obviously there are other factors and if it takes more gas, it takes it… Mpeltier I saw in different post where you mention using 2 Steel and 3 Alum pieces in the buffer did your guns seem to want a buffer weight greater than 3oz ? Thanks for the help... Link to comment Share on other sites More sharing options...
ChrisMcCracken Posted September 1, 2009 Share Posted September 1, 2009 (edited) While my recent difficulties in my Firebird are most likely mag and operator error, Jim raised some concern for the Ti carrier I'm shooting being the cause if I can ever prove its not the mags or the monkey behind trigger. Now I read this thread and a couple questions pop up... 1) Like JP's my firebird is damn tight possibly requiring break in 2) maybe the low mass carrier isn't all its cracked up to be. I was a physics major some years ago. This problem just gives me bad flashbacks to poorly worded questions trying to figure out which part of the problem fits which variable in the equation. The spring is a reservoir for energy, to turn kinetic into potential and back into kinetic. Damn, now I'm going to have to go dig out my intro to mechanics just to satisfy my own curiousity. On an aside: should carriers be completely swappable or would I need to worry about fitting a carrier to work in a particular upper? Edited September 1, 2009 by Erucolindon Link to comment Share on other sites More sharing options...
mpeltier Posted September 1, 2009 Share Posted September 1, 2009 I appreciate all the responses so far guys. I guess I don’t really care how much gas it uses my main goals are.1) Maintain reliability 2) Get the most out of the system 3) See/feel a noticeable improvement To answer a couple of the questions above. I always shoot 62 grain Wolf (I know, I know but it’s cheap) The Gas block was installed as recommended ~4 years ago I didn’t get the JP buffer because of the $50 price difference and this thread which gave me the idea. I was able to confirm today that the modified buffer was 3.04oz per my local Food Lion deli. I have installed the original bolt and carrier with the lighter buffer and been able to cut the gas back to 2.5-3 turns open as it was originally. I think this eliminates the gas block and gas tube in the equation. Smokshwn I agree/understand > Force = mass x velocity squared, related to the spring but why does it take more Gas Force to move a lesser mass carrier ? > Force = Mass x Acceleration I’m not here to argue, I just want to understand obviously there are other factors and if it takes more gas, it takes it… Mpeltier I saw in different post where you mention using 2 Steel and 3 Alum pieces in the buffer did your guns seem to want a buffer weight greater than 3oz ? Thanks for the help... One of my rifles liked a tad more weight, the other liked it at 3.0 oz. I have found there are a good many variables and each gun is just a little differant. The one that likes more weight is a mid-length gas. Link to comment Share on other sites More sharing options...
gotm4 Posted September 1, 2009 Share Posted September 1, 2009 Run it very wet. It does need more gas because it has less momemtum when moving thus it runs out of energy sooner. When used in conjunction with a JP gas block and a muzzle brake/comp it does a very nice job of reducing muzzle lift and felt recoil. Link to comment Share on other sites More sharing options...
Sako92S Posted September 2, 2009 Share Posted September 2, 2009 (edited) I always shoot 62 grain Wolf (I know, I know but it’s cheap)I have installed the original bolt and carrier with the lighter buffer and been able to cut the gas back to 2.5-3 turns open as it was originally. I think this eliminates the gas block and gas tube in the equation. I think Wolf is one reason for your problems. That ammo's gas pressure is low level. Change the ammo to 55gr Federal or similar. We have some experience here of Wolff ammo both 55gr and 62gr. Yes, mine worked also fine with normal carrier but with lightened carier it didn't work with any gas settings I used Change the tube, it only costs couple of bucks. Edited September 2, 2009 by Sako92S Link to comment Share on other sites More sharing options...
00bullitt Posted September 2, 2009 Share Posted September 2, 2009 I always shoot 62 grain Wolf (I know, I know but it’s cheap)I have installed the original bolt and carrier with the lighter buffer and been able to cut the gas back to 2.5-3 turns open as it was originally. I think this eliminates the gas block and gas tube in the equation. I think Wolf is one reason for your problems. That ammo's gas pressure is low level. Change the ammo to 55gr Federal or similar. We have some experience here of Wolff ammo both 55gr and 62gr. Yes, mine worked also fine with normal carrier but with lightened carier it didn't work with any gas settings I used Change the tube, it only costs couple of bucks. Listen to what Sako92 is saying. Seriously consider changing your gas tube if you run that much Wolf. Gas tubes are cheap. Get used to changing it every 3000 rounds as a preventaitve. Wolf kills gas tubes. Especially in AR variant 308's. You can try removing it and soaking it in Kroil for about 48 hours but that is still questionable. Link to comment Share on other sites More sharing options...
lefty556 Posted September 2, 2009 Share Posted September 2, 2009 Put a JP trigger/Speed hammer in the gun. If my brain is working correctly, all of the paperwork I ever received with John's alloy carriers said "USE ONLY A JP SPEED HAMMER WITH THIS PART", or something along those lines. Link to comment Share on other sites More sharing options...
Merlin Orr Posted September 2, 2009 Share Posted September 2, 2009 (edited) I run a JP LM SS in my rifle and use a gently massaged stock buffer and spring. JP trigger and a self modded factory hammer. No problems ever unless I forget to oil, oil, oil.... I do change my gas tube just about anytime I tear down my rifle. (about 2 or 3 gas tubes per barrel life - usually at about ~ 2500 rounds per new tube) Make sure your gas block is aligned properly and the tube itself is not hitting or rubbing hard in the bolt carrier. Tubes are cheap. My .02. Edited September 2, 2009 by Merlin Orr Link to comment Share on other sites More sharing options...
bigbrowndog Posted September 3, 2009 Share Posted September 3, 2009 Todd, how many wolf's does it take to kill a gas tube??? i've fired many and never had any problems, of course now I will but thats not the point. what is the basis for your info???? Trapr Link to comment Share on other sites More sharing options...
00bullitt Posted September 3, 2009 Share Posted September 3, 2009 Trapr.......I suppose it will vary on how many wolves it takes based on how hungry they are and their size. On some of the DPMS 308 guns that a few of us shoot.......we shoot alot of Wolf through them. After a couple thousand we started getting short stroking and could not find the culprit. Rob finally pulled a tube off and tried to blow through it and it was quite hard compared to a new tube. So now......we just kind treat it as preventative maintenance. We changed the gas tube on the problem guns and they ran fine again. When I get a more finite number on how many Wolf it take.....I'll holler at ya. Link to comment Share on other sites More sharing options...
jobob Posted September 3, 2009 Share Posted September 3, 2009 (edited) Wolf burns dirty all right, but it isn't loaded light. I chrono'd some 55 gr. recently and it was up to about the same speed as Remington. Faster than PMC and nearly up to Federal AE. This talk has got me thinking. I've been trying to reduce the muzzle jump on my POF. It's piston operated, so maybe adding a JP lightweight buffer may help. Unfortunately getting a light carrier isn't in the cards. Edited September 3, 2009 by jobob Link to comment Share on other sites More sharing options...
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