Which Jp Barrel Profile? Rifle Advice?

[Zak Smith]

I'll hopefully have the wampum on hand in a month or two to order a JP CTR-02, so I'm trying to figure out exactly what I want.

This will be in .223, and I'm not yet sure if I want the .223 chamber or 5.56 chamber.

The rifle will be used for local 3Gun matches in Colorado, RM3G, SMM3G, the ITRC in Gilette (if I can find a partner), and maybe NA3Gun or MGM if I can get the time off.

It will be set up for "Modified/Tactical" class most often, using a TA11, will have the BC comp installed, and the low-mass bolt carrier assembly.

My question is primarily in regard to the barrel profile. JP offers three barrel choices appropriate for a 3Gun rifle: the Ultralight 18" (.500 under handguard, .750 at gas block to muzzle, about 6lbs), the Lightweight "Medium" 18 and 20" (.750 under handguard, .936 at gas block, .875 to muzzle, about 7.5-8lbs). I think you can only get the 1-in-8" twist on the 20" barrels.

Which would be the best choice for a 3Gun AR to shoot those matches? I don't mind length necessarily; I am probably more sensitive to mass. I would prefer to be able to shoot the 75/77gr bullets if the need arises.

Those of you with experience with the JP barrels, which length/contour do you prefer and why?

How about experience mounting a TA11 on a CTR? I'm currently using an ARMS #19S on my Rock River.

thanks much,

Zak Smith

[kurtm]

Zak:

The next time you are down to Denver for a Rocky Mountain 3-gun, hook up with either Blane West or Jimmie Holdsworth, and ask to try out one of thier rifles for a few rounds. We all shoot for J.P. so you can try befor you buy! The quick answer is get what ever you like as J.P.'s quality is second to none, and this is true!!!

I think for what you want to use the carbine for, I would stay with a 20" barrel in the light weight profile. You can get it in 1 in 9 and 1 in 8, and if you are going to use that heavy of a bullet get the 1 in 8. Part of the reason to stay with 20" is that most bullets will match your BC in the TA-11 if pushed fast. The matches you want to shoot push long range shooting, and that wieght seems to be about the best. As an aside J.P. has found that the light weight barrel is a bit more accurate than the bull barrels for some unknown reason.

We all love the J.P. upper reciever already milled for the Trijicon scope. No extra base needed! although I'm not sure I would reconfigure the rifle to much as the matches you have mentioned all recognise "tactical" class so leave that thing mounted!! the ARMS mount would also work on the J.P. upper so no worries there!!!

I have found that to light a rifle tends to over swing a target, as well as a to heavy. The light weight seems about right, especially with the low mass carrier ( as Mike45 says... top shelf!!!) You can't go wrong anyway you go, but that is my recomendation.

By the way say Hi to my brother next RM3G you shoot, Eric Miller! Good luck Zak, and I wish I were back in Colorado to meet you, also say Hi to Hung Dang and Dean Culver, all great people!!! KURT

[George]

Hi Zak,

I have the 1:8 20" "Lightweight/Medium" with the SAAMI .223 chamber size and I love it and it loves the Sierra 69 & 77 grain projectiles. It holds 1.25-1.5 MOA with most good 55 grain ball, 3/4 MOA with the S69 and 1/2 MOA(or better) with the S77 (non Moly).

I like the slightly heavier barrel option for heat stability reasons and the little extra mass because as Kurt mentioned this does indeed make for a rifle that is less twitchy when holding. My 20" JP has been through 2 MGM Iron Mans and it still holds 1/2 MOA with my good 77gr fodder. I attribute this hardiness to the heavier profile, the Cryo treatment that they do at JP and to the Tubbs FinalFinish rounds that I use every 4-500 rounds to clean up barrel throat erosion. I am at just over 6k rounds on my barrel and the freebore is still about the same as when it was new so the Tubbs rounds are performing as advertised in reducing throat erosion and extending accurate barrel life. I never broke the barrel in, just started shooting it because that is what John Paul said to do with it.

The .223 chamber dimension is most desireable if you load your own for the utmost in accuracy. The NATO 5.56 chamber size is just a little larger in a couple dims to accomodate ammo variances and fouling buildup and I would avoid it unless you are gonna shoot a lot of cheap surplus ball and don't care about the nth degree in accuracy compared to fodder tolerance.

BTW, also get a JP ammo drop gauge that is cut from the same chamber reamer as your rifle. the JP chambers are tight enough that normal SAAMI gauges (L.E. Wilson for example) will pass cases that are tight or a no-go in the JP gauge.

You will love your JP, they are really fine tools.

Regards,

[Zak Smith]

Thanks for the info, Kurt and George.

That's two votes for the 20". Does anyone prefer the 18" barrel, and why?

Anyone have some direct data on typical loads from 20" vs. 18" barrels?

How about twist? If 1-in-9 is good for the SMK69's, is that good enough, or is 1-in-8 really better (so >= 75's can be used)?

thanks

Zak

[kellyn]

My favorite AR (an Accuracy Speaks) has an 18 inch barrel with a 1 in 9 twist w/ a medium contour with cool go fast fluting. It will shoot Hornady 75s but I don't know about Sierra 77s. It really shoots 69 Sierras and 40 VMax. But if you really want to shoot 75/77s get a 1 in 8. I really like the feel of the 18 incher but Kurt makes a good point about getting the most velocity you can to match the BDC, especially with the heavier bullets. But I have not had a problem with my TA11 on that rifle shooting 69s. I have not REALLY played around with any other bullet in my TA11 so I will have to defer to Kurt who is the TA11 guru.

I have a JP 20 incher that I really like, it is a heavier contour. It shoots like a house a fire with 40s to 75s too. It is also a 1 in 9. That rifle feels good but not as much as the 18.

I have to agree with the comment about the ACOG "mount" milled into the JP receiver, that's %$^)# cool!

I really don't think it makes much difference at all but theoretically, I'd prefer an 18 in gun for NA3Gun and MM3G (closer shots/more contorted postions) and a 20 for RM3G (some real rifle shooting). In the end, a good zero, sight picture, and trigger squeeze is what's going to win, not a "X" barrel with "Y" bullet.

[lucas]

I went with the 18" LW 1/9.I like having a little lighter gun than the 20" and dont think i give up that much FPS as compared to 20.The 1/9 223 chamber didnt bother me because i planned on not shooting heavier than 69gr .

[Zak Smith]

The 18 LW/Med is only about 5oz lighter than the 20 LW/Med, right?

[lucas]

The intermediate/LW 18" is 7 3/4 Ib.

LW 20" is 8 Ib

[dirtypool40]

Glad I found this thread, you guys ahve answered most of my questions before I could even ask them!!

The one I still have is making minor. No one mentions it, and I am 99% sure I want an 18 LW, but do they make minor?

I am planning on the USPSA 3-gun nats this year, and want a cool JP AR. BUT!! I DO NOT WANT TO MINOR.

They tell me it will make it, but I want to hear from you guys.

Thanks in advance...

[Zak Smith]

dirtypool40,

With what ammo?

Out of my 16": Black Hills 68gr is about 180PF; South African "M193" 55gr is about 168PF, IMI M855 62gr is about 184PF. Black Hills 55gr was only 155PF, however.

The concensus is that any "real" M193 will make minor out of a 16". All factory loads for 68gr or heavier will make minor.

So with 18", it'll be even easier.

-z