TitoR

Thanks for the advice. Since I want to avoid removing the handguard for adjustment of the GB, I'll probably have to avoid the loctite 2620. Lucky, should I use the hight temp RTV on the thread instead? Same reason as above, since I drilled a hole on my handguard to put the allen wrench for adjustment, so not much room to apply a dab of RTV.

Just completed adjusting the gas block on my 3gun AR. I've been using blue loctite, but I've found the screw loosens after the block heats up. What loctite product should I use?

OK, I finally got around to do some additional testing and I would like to validate my conclusions. I have three buffer springs, CAR, Rifle and JP Rifle; and two buffers: JP and STD Rifle. I measured the start and final force of the spring in the buffer tube to come up with the spring rate. I used a travel distance of about 1.6 in. Here is the data: CAR. 5.125 lb and 7.75 lb for a spring rate of 1.68 lb/in RIFLE. 6.25 lb and 8.438 lb for a, pring rate of 1.4 lb/in JP. 7.25 lb and 9.813 lb for a spring rate of 1.64 lb/in The JP buffer weights 3.25 oz., while the rifle buffer 5.125 oz. Next, I went to the range to adjust the gas block with all the combinatioms of springs and buffer for reliable lock back with empty mag. For the JP and STD springs I had to open the gas block 4 turns for the JP buffer and 4.5 turns for the Rifle buffer. I was surprised about this since the Rifle spring rate is lower than JP's as well as having a lower starting force, which should have allowed the BCG to cycle with less gas. With the CAR spring I had to open the gas block 3.5 turns for the JP buffer and 4 turns for the Rifle buffer. This makes sense, since the starting force is much less than the JP and Rifle springs, althought the spring rate is higher of the three. My conclusion was that the gas block was only slightly throttling down the gas volume that the barrel gas port was allowing to operate the system, but mainly the barrel port is controlling the rifle cycling. Is my conclusion correct? Thanks in advance for the feedback.

I had he same situation a year ago when I did my build. I essentially have the same setup. Carbon Arms 18" rifle gas barrel, JP adj gas block, JP Low mass BC, and low mass rifle buffer. With JP buffer spring it would not lock back with Tulammo, and was barely locking back with brass 55g factory ammo, with the GB fully open. With a standard rifle buffer spring, is currently working fine with brass ammo, but still can't cycle cheap steel case ammo. My conclusion was that the system needed break in and more gas, but the barrel gas port is optimized for non-adjustable GB, so I am waiting to get to the 1000 round mark before I do any other changes since the rifle is running very well. If you ever decide to drill out the gas port, please post your results.

i used the nordic components speed button on mine, but installation was hard, four drill bits broken. That bolt release is really hard. Have not gone to a match yet with it, so do not have functionality feedback yet.

reported factory muzzle velocity, i do not have a chrono, unfortunately.

Why not a 75 yds zero? With my scope height and .223 55g 3240fps, the bullet is within 2 inches, up or down, from 20 to 235 yds, with a drop of 7" @ 300 yds and 20" at 400 yds. Granted, my local matches never go past 100 yds, so a flatter trajectory is my preference.

Jesse This is how I break down the Pros and cons of WH vs SH SH Pros +More dexterity by using the strong hand +Easier to deal with when a slide lock occurs +Closer to face, so better visual indexing SH Cons -I burn my hand every time, unless I keep WH wrist in awkward position -Mounting SG is less consistent - trigger grabbing at re-mount WH Pros +Closer to belt so faster hand to SG movements +SH never leaves SG grip +Familiar SG mounting movement +Good visual indexing +No hand burning WH Cons -Hard to resolve slide lock loading ( I know I should be counting my rounds) -Dexterity requires more practice I did not consciously put this list together before I started WH, but burning my hand on the barrel during early practice rounds was definitely one of the reasons I started with WH. I never thought of the re-mounting motion or trigger grabbing until you mentioned it, but definitely important.

Ok, i get that load 2/4 is easier to learn, but which hand is more efficient: WH or SH? I personally skipped weakhand caddy reloads and went straight into WH Load 2, been a newbie and having an unmodified JM Pro, but most of the videos here are of strong hand load 4. Am I missing something?

A secondary idle stop screw from Holley works great and is self tensioning in the JP block Where can I buy the idle screw?

2 - 30 rds, 2 - 20 rds & a 30 +18 or 48 rds using Nordic extension. But at the end of the day, stage design dictates what magazine to use. Regards

Built my own, broke it in and it is more than fine. Building your own is like building a Lego set for adults.

18" SS carbon arms w/ rifle gas 1/8 twist Wilde chamber

I had a similar situation with my JP Low mass buffer, BC, GB and tuned spring, combined with Carbon Arms 18" barrel and rifle gas system. With full gas, bolt will not stay open with an empty chamber and occasionally will have double feeds. Fix - changed JP's tuned buffer spring for a regular DPMS buffer spring and avoided TULAMMO, use only brass cartridges. Not a perfect fix in IMO, but now I have a functional rifle. Gas block adjusted to 3/4 open. Hope this helps.

Mack, I am experiencing a similar problem and was wondering if you were able to fix your SG. In my case, if I press the bolt release with the SG loaded, the magazine will spit out two shell jamming the SG. To clear, I have to hold the bolt open, push one of the shells back in the magazine and then release the bolt to load the second shell. Questions: 1. Can this be caused by an extra long magazine spring? What is the correct length for the magazine spring used in the JM Pro 24"? 2. Did the shell catch polishing resolve your issue?

Alternatively, Versmax Tactical available in Bud's Guns for $1183 cash.

Ap customs for carbon fiber, with an w/o top picatinny rail.

Ap customs for carbon fiber, with an w/o top picatinny rail.

Craig, the rifle is cycling and locking back correctly with brass case ammo. With tulammo, the casing does not release from the chamber (Wylde) and the cycle stops and I have to extract the spent casing with the charging handle. This means I have to stick with brass cased ammo for now.

Glad to report that the rifle finally worked with 55g ammo, specifically American eagle FMJ. The trick was the mil spec spring with the JP low mass buffer and BCG. But mostly, I believe it was a lubrication issue. I went to the range with the rifle dropping wet with CLP, and it ran with 55g with the same gas setting as the 69g fed premium, with the mil-spec buffer and spring. Still it won't cycle tulammo. This was a limited test, still need to run several hundred rounds to break the rifle in, but now I can do it with full mags. BTW, any recommendations on best lubricant for competition use?

Heshin, thanks for your reply. I only have the JP LMOS BCG, so I'm stuck with it. So, let me see if I understand. I still want to keep the overall mass low, even though the rifle is showing signs of undergasing which is causing short stroking? And on my test with the mil spec buffer and buffer spring, the real help was the spring and not the buffer? So, if I switch to a "softer" spring by either cutting coils from the mil spec spring or getting a carbine spring for my rifle length tube, it would allow the BCG/Buffer to move all the way back and stop with the magazine catch? BTW, is the carbine spring in a rifle tube a good substitute for cutting coils from a rifle length buffer spring for this issue? I hesitant to start cutting coils. I did not try the JP LMOS BCG with the mil-spec spring and JP lightweight buffer, so I'll add it for my next range session. I'm also buying a carbine spring to use in the rifle length buffer tube, which I'm planning to test too. BTW, I failed to mention that this is my first build and my first 3 gun rifle too, so I can use all the help you can provide. And, yes I am an engineer who likes to DIY.

Ok, here is the latest range report. Changed the JP spring and buffer for mil spec units and was able to adjust the gas block 4 1/2 turns to run with the 69g Fed Premium ammo. Ran out of ammo, so tried the tulammo, but did not work even after fully opening the gas block. Next, buy more ultramax ammo and run test again, but this time I am bringing my dremel to start cutting the spring. Any recommendation on how much to cut at a time or the maximum before I start running into bolt closing issues or feeding issues?

MarkCO Here is a photo of the gas tube at the gas block. Do you consider this carbon sooting abnormal? Thanks

MarkCO, thanks for the advice. Several instance of people suggesting that the rifle needs more momentum (mass) or less resistance (spring). This how I am planning to proceed: 1. Re-check all gas connections: gas block to barrel gas port alignment, gas tube to gas block fit, gas tube to gas key fit, gas key tightness to carrier bolt, verify gas passage through gas key to carrier, and gas rings fit to carrier bolt. 2. Swap JP spring for mil spec buffer spring. Adjust gas and test. If it does not work, keep change and then, 3. Swap JP LMOS buffer for mil-spec buffer. Adjust gas and test. If does not work, keep change and then, 4. Swap my bolt for my brother's bolt. If does not work, revert all changes and then, 5. Star cutting mil-spec buffer spring 1 coil at a time. I am out of ideas after 5 above. Anything else I should try? BTW, is there a Loctite product that could be used to seal gas tube to gas block or the gas key to the carrier? I'm waiting for an order from Brownells to start the troubleshooting again. I'll rout back on my findings, as it may help others.

It's my first build and the bolt has three regular rings, staggered. I am waiting for a Brownells order with a standard spring and buffer to test the "too light" theory.