JP rifles

[m77mkii]

Just wondering what the guys who own JP's have found to be their most accurate load? I myself am having trouble finding a sub 1 inch load.

[StoneHendge]

How does yours shoot 123 Hornady Black? My 22" barrel kit does about 5/8" with it. if your not getting sub MOA with black, there's a problem somewhere......

[Herodrh]

Just wondering what the guys who own JP's have found to be their most accurate load? I myself am having trouble finding a sub 1 inch load.

Hello there, I'm the owner of a JP-15 18" medium contour build. I have shot only the Hornady 123 grain SST load of which it hold 1/2 inch easily. I'm told the Amax load would essentially duplicate this performance in a non expanding match type bullet. I just received a 200 round case of the new Hornady Black 123 grain ELD M loads and can't wait to try them. Honestly as another poster stated, if your bases and rings are tight and fundamentals are good there might be a problem with your rifle. I can't speak to handloads -bullets/powders etc since I don't reload. These factory loads should go 3/4 inch all day from a well built rifle - even a lightweight rig. I will tell you though that a heavy and or gritty trigger pull will increase the size of your groups with any load. Of course handloaded rounds add endless variables. Tighten all mounts, possibly lap in your rings then torque everything down. Then address that trigger and you should be in the hunt!

[Herodrh]

JP rifles: loads,accuracy applicable to JP Grendel builds

As a JP grendel owner and other JP calibers/builds I have another comment germane to this discussion. All of my JP's share the same characteristic which some of the purists may decry: they like to shoot dirty and hot. After doing your barrel break in you will find that the JP supermatch barrels will not shoot consistently or to zero right after a thorough bore scrubbing (especially with copper remover or JB compound). I find it takes 20-30 shots to foul the barrel in order to return to zero and consistent grouping. I can't tell you how many range sessions I would chase my zero until I discovered this. John Paul at JP suggests a 200 round interval between bore cleaning probably with this in mind. My theory as to why this holds true is (although extremely tight land dimensions) the bores are just glassy smooth and foul very slowly. My guess is that uniform fouling 360 degrees around the bore is necessary to release the bullet consistently. There are probably better and more informed theories on this. They also seem to shoot very well when they are good and hot. These are cryo treated barrels so some metallurgical magic may come into play. If you are constantly cleaning and shooting your JP you will be chasing gremlins with a very low satisfaction quotient. Just sharing my personal experience with my JP's in hopes of benefitting others. RHH

[hikfromstik]

Is this a JP complete factory bought rifle or a build or just a JP barrel in another manufacturer upper ? If not complete JP rifle then check gas tube to see if it's free floating and not touching the sides of the gas key , check muzzle device for tightness, check gas block to make sure it's not too tight and squeezing barrel and causing pressure points , make sure barrel nut is properly tightened , check scope/site mounts for tightness , study your shooting technique and trigger-finger contact . It's probably optic/mounts related or your technique , but check out every thing else just to be sure .

[acourvil]

I have a 22' JP-15. It has shot sub MOA with most of the ammo I have tried, except it doesn't seem to like lead-free ammo, where I get maybe 1 to 1-1/2 MOA. My favorites are the Berger 130 AR Hybrids, but it shoots 123gn scenar, 120gn scenar-L, 123 AMAX and 123 SSTs l better than MOA.

[m77mkii]

will go through all of these ideas one at a time,that dirty barrel one is very intriguing.Have another rifle like that.Your replies are greatly appreciated.

[Herodrh]

I'm glad you liked my post. Most of us go out and punch paper on saturdays or sundays and shoot some steel or whatever. Then when dialed in with our chosen loads, some of us even venture forth into the wilds to harvest some game with our fav AR build. But, if you talk to match shooters who compete for scores at distant tiny target bulls you will hear even more about these fouled bores. Most I have spoken with would not dream of cleaning their bores prior to a match once zero has been established for a particular load. I have even spoken to a few who won't clean for a season. These guys are shooting high power over the course at 600 yards and some even Palma match shooter (which of course we are talking about 1000 yard competition). Of course there is a middle ground but honestly I have personally chased my own zero around until I figured out what the rifles want. Fouling in the bore is not necessarily a "dirty bore" per se but terminology is fungible. Speak to military snipers about this and you will get eye opening replies. None of these guys will go out with a scrubbed clean bore in their long range sniping rig. The ability to make a cold bore 1st shot is paramount for them - not going to happen with a clean, oiled rifle bore. Now then, that said I am particularly describing the conditions which are present in match grade top tier rifle barrels - not production hunting rifles you buy at the sporting goods store. Match grade bores are uniform in land and groove diameters in the extreme and usually hand lapped to glassy smoothness. Fouling forms slowly and evenly as a rule. That is why they shoot the way they do. Production guns have bores that have variations in land and groove diameter as you move through the length and they may be rough to one degree or another and foul (both copper and powder residue) quickly. With the latter, cleaning may be required more often to maintain accuracy. The match grade barrels are a law unto themselves but of course your mileage may vary. If you really want to get into the weeds, do some reading up on the phenomenon barrel makers and match shooters speak of as copper equilibrium and its effect on accuracy and zero! Just food for thought.

[Bruw]

That is interesting. I was shooting my 18" JP barreled 6.5 Grendel yesterday and had a similar result. The first 18 rounds were shooting groups that were about 1.5" with an occasional flyer. Not bad, but nothing like what I hoped for from this barrel. After a fair bit of cussing and trying to figure out what I was doing wrong, changed my target and banged out a 5 shot sub 1" group. In thinking back, I had the exact same results the first time I took that rifle out. I cleaned it very thoroughly, thinking it was a good idea for break in, and then yesterday had the same experience. Unfortunately, I cleaned the crap out of it again last night. I will play close attention to how it handles the first 20 rounds or so next time out and how things go after that. Thanks for the observation. I would have beat myself up for quite awhile assuming it was me before ever thinking the barrel just doesn't like being shiny clean.

I will try to remember to update this thread after I shoot it next time.

[SightedIn]

My only JP barrel is an 18". When I first got it I was quite disappointed in its accuracy. Then I stopped cleaning it, and yep accuracy improved dramatically. I would find out later its a known thing with competitive shooters, not cleaning barrels too often. Powder used has a lot to do with it.
I suspect that's why I never had good luck with CFE223 powder( could never get a better than 1.50moa load), I didn't give the barrel enough time with the new powder.

My most accurate load for that rifle bty is 28.0gr of XBR8208 pushing 123 Amaxs', averaging .80MOA, sometimes better.
If I clean the barrel it jumps to 1.25" for a bit before it settles back in.

[Kilco]

https://youtu.be/GcmuSXqmKjs

I'm a stickler on powder fouling, but careful not to remove copper fouling until accuracy starts to degrade.

[m77mkii]

I spoke to a friend of mine who was a army team shooter long ago,he said to wet patch the rifle till nothing comes out.Let some "dirt" build up in the barrel and it will get tighter.Meaning grouping.Just gonna have to try this advice ,coming from different places.

[Vilk]

Dear JP fans,
me and my wife we have two custom 22" made by JP Grendels. With heat dissipators.
These are most difficult ARs we ever had to tune/reload for. And we are experienced F-Class and semi shooters >20 yrs.
When cold,the POI will walk 3-4" vertically to warm zero.
When clean and cold, for 20 shots it will just shoot everywhere (with top quality reloads).
To get a cloverleaf,we need min 20 rounds to foul/get warm.
When they cool off,POI walks again. We keep scratching our heads.
Will try your no clean advice!

[Bigs28]

I would call jp first