AlbinLee
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Well JP Enterprises founder John Paul recommends using the old military style brass/steel bristle combo brushes on his $3000+ rifles. He even goes so far as to recommend chucking the brush in a cordless drill and spin at low RPM with the chamber brush in the chamber (soaked with solvent). Then follow up with a mop and/or q-tips to dry the solvent and that's it! This advice can be seen in the Gas Gun Basics DVD (came with my JP-15). While I don't have the balls to run the chamber brush in a power drill, I certainly have no fear of hand spinning the brush. Just push the brush in through the lugs with a good, fixed handle rod (upper receiver guide is nice to have, such as the one J. Dewey provides with their AR-15 cleaning kit). Spin the brush clockwise in the chamber so the attachment doesn't back off the threaded end, maybe 5-10 good rotations. I found that it is easier to pass the steel bristles in and out of the locking lugs by rotating as you push the brush into the chamber, as well as pulling it back out. Don't worry about the steel bristles, they are very soft, and the locking lugs/chamber are extremely hard. You couldn't scratch that steel if you tried. Just be careful while passing the brush through the receiver, and you shouldn't have any problems. I follow this method every time I clean the bore, which is every 200-300 rounds.
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JP Adjustable Gas Block - Technical Question
AlbinLee replied to AlbinLee's topic in Rifle - Technical
It appears you are dead on! I took the rifle back out over the weekend to tune it again, and it only took about 1/8th of a full turn out before the set screw was tightened firmly and function was back to normal. I hadn't considered that the set screw could be reducing the flow of gas, if only by a very small amount. After opening the valve a little and locking the set screw, I had 55 grain factory loads ejecting between 2:30 and 3:30 pretty consistently (PMC around 3:30, AM Eagle at about 3:00, and Hornady Varmint at about 2:30). I believe this variance in ejection is normal considering the difference in powder and velocity of each of the 55 gr loads. The Hornady was considerably hotter than the PMC. Most importantly, all three ammunition types cycled well and engaged the bolt catch on the last round, indicating bolt velocity is within the operational window with each load. Thanks for the tip! -
For those who are interested, I just posted the follow up to my JP build with pics over here: http://www.brianenos.com/forums/index.php?showtopic=213358 I was able to get the gas system tuned up nicely, and have the operating window functioning flawlessly with three different factory loads in 55 gr. Oddly, when I tighten the set screw to lock in the valve screw, the bolt fails to lock on an empty mag. When I back the set screw out a half turn, it goes back to perfect function. According to a phone call I made to JP during my build process, the carbon buildup locks the valve screw in place on the JP adjustable gas block, and that JP only recently added the set screw in response to the onslaught of questions they received about the design. Supposedly, they had adjustable blocks without the set screw for years that functioned well. I plan to give them a call Monday to ask about the set screw, but currently I am just curious if anyone has seen similar issues? I am perfectly content to run the rifle in its current setting and let the carbon lock the valve screw in, keeping the set screw backed off slightly, but I am definitely curious about it. Thanks, Al
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Laser engraving looks awesome And here is my first attempt at any sort of group after the 60 round break in. I was shooting at 50 m because that is where I chose to zero my irons/red dot. This group was 4 rounds (not trying to be official here, just for fun), PMC cheapo, through the unmagnified red dot (2 MOA dot). First shot was a flyer, last three grouped nicely: I would love to put my Leupold VX-2 3x9 on this baby and really see what she can do with the Hornady ammo at 100m! Just need to get a good mount.
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First build concept in GunStruction, before I had chosen to buy from JP... And here she is!
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UPDATE! I picked up the rifle from my FFL about 2 weeks ago, which was awesome... no "further review" so I got to take the rifle home same day. My FFL is a good friend from competition shooting who does transfers and direct dealer sales for friends and folks who contact him. When I went to pick up my JP, we BS'd for an hour and a half about 3-gun and he showed me a few of his AR builds, one being almost identical to mine. The JP rifle is an absolute work of art. Upper/lower fit is perfectly tight, but the pins can be pushed through with finger pressure only (pretty impressive). Every single roll pin is perfectly seated, with no marring around the holes whatsoever, not even a speck. Laser engraving looks awesome! Overall my impression out of the box is that this rifle is well-deserving of the praise it is given from owners. Although I was nervous about the added weight of the dissipator, my assumption of the overall balance was spot-on. The rifle balance point is exactly at the rear of the barrel nut/front of the lower receiver. At 7.5 lbs, the rifle feels a little heavy, but that was a sacrifice I was willing to make for the dissipator. It took two range trips to get the barrel broken in, per the JP Owner's manual. Essentially fire 20 rounds, solvent clean, JB bore compound (5-10 strokes), solvent, then dry patches. Repeat three times for a total of 60 rounds. The barrel is essentially broken in, but JP recommends one final JB cleaning after 300 rounds. I found it a bit tricky to get the adjustable gas setting tuned up though! I am new to the LMOS, and AR's in general, so it was definitely a learning experience. From the factory, they tune with 55 gr ball ammo before sending the rifle. From the beginning, I was getting failures to reliably lock open on an empty mag. I began opening the gas port a quarter turn at a time, but issues continued... I had no idea the rifle was OVER-gassed from the factory! Woops. After finally figuring this out, I turned the gas completely shut, then started over. It didn't take long to find a gas setting that locked reliably with 3 different brands of 55 gr ammo (PMC, AM Eagle, and Hornady Varmint). I am pretty happy that the operating window is wide enough to accommodate three different 55 gr loads of varying velocity. Pictures will be forthcoming!
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Good solutions for dealing with handguard heat in an AR
AlbinLee replied to Nemesis Lead's topic in Rifle - Technical
Well if you don't mind a little extra weight in the front end... (Ref: canon3825, http://www.ar15.com/forums/t_6_23/245336_.html) -
That sounds like it will be a beast. The Armageddon trigger has gotten alot of praise from all of the articles/reviews I have seen. And the 17.25 should look sweet, probably alot like having the 15.5 handguard and a 16" bbl. The ACE skeleton stock was my second choice, but I really do like to have an adjustable length of pull for shooting prone, kneeling, standing, etc. The TI-7 looked like a mix between the CTR and Sopmod, so I am going to give it a shot. Who knows, I may end up with an ACE at some point as well. I plan to shoot limited for starters, so I bought a Primary Arms MD-ADS red dot. Glass is super clear, unbelievable actually for an imported optic. A good friend of mine has an Aimpoint PRO (not the micro, like my MD-ADS), and I have to say the quality compares favorably at 1/2 the price. I would love to get my hands on a Micro T-1 to compare apples to apples. Not saying that the MD-ADS=T-1, but for 1/4 the price it is really impressive.
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Awesome! You should post your final build specs. I made my order on 4/13, and they sent me an estimate on 4/14. I mailed them a check to take advantage of their free shipping offer, and they sent me the official sales order on 4/20. Tomorrow it will have been 7 weeks, and they estimated 6-8 weeks for the build. The only reason I anticipate that my build is reaching the upper limit of their estimate is due to the laser engraving, but that shouldn't put it outside of 8 weeks. Unless you requested a custom Cerakote finish, I would guess you will be looking at a similar wait. It goes by fast when you get over the initial excitement of placing the order...
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Well there are two things to consider. The Rapid Config Mark 3 only comes in 15" max length (as far as I can tell by the JP site?), and the Signature Mark 3 extends to 17.5". The Signature tube is 3.12 ounces heaver in 15" than the Rapid (also in 15"). Extending to the 17.5" Signature adds another 1.56 ounces above that. So assuming you have roughly the same build (butt-stock can be a major variance), your overall weights would come to around 7.9 lbs with the Thermal Dissipator, or 7.5 lbs without. Depending on who you talk to, there are folks who might suggest a slightly heavier butt-stock than the TI-7 (12 ounces) or CTR (9.6 ounces) in order to balance those extra 4.68 ounces at the muzzle. Admittedly, my build may be slightly front heavy with the Dissipator, but I am going to give it a shot. The center of mass of the Dissipator, however, is much closer to the receiver (about 5 inches from chamber). All that being said... It's hard to say how the rifle will balance until you hold and shoot it! I will definitely keep you guys posted on how this weight/balance thing shakes out.
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Well after much research and planning, the order has been placed! I decided to pretty much stick with the original build specs I highlighted in the OP. As for the Thermal Dissipator, I have seen that most folks are pretty split as to whether the benefit is worth the weight/cost. As I mentioned before, my goal was a 7-8 lb rifle unloaded, and I met that pretty easily. I have a pretty involved Excel spreadsheet that lists a variety of parts for each category, and allows me to mix and match them to approximate the build weight overall. With the Dissipator, I am looking at around 7.6 lbs (7.2 without), including BUS but no optic or magazine. I even listed around 10 of the most popular 18" bbl, 3-gun ready builds from various manufacturers (Bushmaster, Stag, Armalite, etc..), and took an average weight. They all clock in around 7.7 lbs average, and obviously none of them have a Dissipator. So overall, I am pleased with the build as a whole. I will keep you guys posted going forward, and maybe throw some pics up in about 6 weeks when the rifle is received. Thanks again for the input!
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This is a wealth of great info from a 2 year JP shooter/owner! Thanks for taking the time to share some of your findings with the build.
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On a semi-related note: Would you guys recommend starting out with a standard set of flip up iron sights? I.E. Magpul, Troy, Diamondhead. My plan was to start out shooting the "USPSA Production" equivalent class in 3-Gun, which I believe is Limited. Should I just buy a set of 45 degree offset sights as my first set, or start with irons and plan to co-witness? You guys seem like you would know.
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Honestly that is probably the best photo on the internet right now showing the Mk3 Rapid knurling. No joke! That is a sweet looking build right there! I really like the blue touches... not overkill. Honestly, I had originally planned to do a complete custom build, maybe 50% JP parts, but the volume of parts on the market right now is super overwhelming. I thought about spending some time at the 3-gun matches (occasionally they run after USPSA on Sunday mornings), but that would be pretty time consuming just to see what manufacturers and parts people trust to game with. It seemed, based on everything I have read and seen, that I could not go wrong with a complete JP build.
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Man that baby looks light with the CF handguard! Have you ever put it on a scale? I was aiming for low 7 lb. range for my build, and with the Mk III Rapid tube and no dissipator it would clock in around 7.18 lb naked. Super impressed with the JP parts coming in that low with mostly aluminum/steel construction!
