JP barrel doesn't like Hornady Black?

[SuperSneakySniper]

Heya,
Ive got a new AR15 build up and running, uses a JP FMOS BCG, 22in 6.5Grendel Barrel with matching bolt, Aero receivers with a triggertech trigger.
It's got about 50 rounds thru it after doing a "barrel break-in" cleaning (if you can call it that).

Im strictly shooting factory ammo at the moment.

It grouped pretty good with Alexander Arms 123gr Lapua ammo. 5-shot groups averaging about 0.7in, with the best group right at 0.5 exactly.

BUT with Hornady Black/ELDM I couldn't get it to shoot 1moa. I shot 5 different groups yesterday with the ammo, the cold bore shot was great, and 2 or 3 bullets will touch, and then 2 shots will open up the group to about 1.1 to 1.4 inches. What gives? I figured it'd perform better considering ive had great luck with JP barrels shooting ELDM factory 6.5CM.

Other JP owners report good submoa performance with Hornady Black.

Do I just need to shoot it some more and let it wear in? I have been told some barrels need to foul a bit more to get decent results.

Im new to precision gas guns so I figured I'd ask you guys what you think.

Thank you for your time!

 

[Downtown]

I'm afraid you've just learned a lesson about gun barrels. Some barrels don't shoot well with some ammunition. This is true from the cheapest Mossberg .22 to the custom Bartlein. Much has been written why this is. In 40 years of shooting, I've learned to accept this.

 

[brazz04]

Thats an odd one, the Hornady Black ELD-M is the standard for sure in the grendel. I have rarely seen a barrel that doesn't shoot that load extremely well.

 

[Downtown]

I agree, that would be my first choice in that caliber. I've just grown to accept some barrels think different. I even once had a 700 barrel that wouldn't shoot 168 FGMM

 

[Trigger Monkey]

^ I have run head long into this issue myself, barrels are rules unto themselves, some companies do better at consistently putting out a good barrel but stuff happens.

 

[LRRPF52]

My Bartlein .260 Rem barrel shoots everything into .4 to .6 MOA 5rd groups, including 139gr Scenar, 123gr Scenar, 142gr SMK, and 130gr VLD. My 140gr Hornady A-MAX loads would not shoot anywhere near as well as the others for some reason. That was before ELD-M existed.

I’ve had excellent results with 123gr A-MAX, 123gr SMK, 120gr Scenar-L, 95gr Lehigh Controlled Chaos, 123gr American Gunner, and 123gr Scenar in 6.5 Grendel even from several really lightweight Lilja barrels. 123gr Hornady American Gunner shot 5rd bugholes from my LaRue 18” Stealth 2.0.

I’ve noticed that if you don’t really settle-in your position into the Natural Point of Aim each time you move to a different dot or bullseye on a paper TGT, you will often see groups open up with gas guns chambered in larger cartridges than .223 Rem/5.56. This is especially true with lightweight Grendels and AR-10s.

 

[Evintos]

Heya,
Ive got a new AR15 build up and running, uses a JP FMOS BCG, 22in 6.5Grendel Barrel with matching bolt, Aero receivers with a triggertech trigger.
It's got about 50 rounds thru it after doing a "barrel break-in" cleaning (if you can call it that).

Im strictly shooting factory ammo at the moment.

It grouped pretty good with Alexander Arms 123gr Lapua ammo. 5-shot groups averaging about 0.7in, with the best group right at 0.5 exactly.

BUT with Hornady Black/ELDM I couldn't get it to shoot 1moa. I shot 5 different groups yesterday with the ammo, the cold bore shot was great, and 2 or 3 bullets will touch, and then 2 shots will open up the group to about 1.1 to 1.4 inches. What gives? I figured it'd perform better considering ive had great luck with JP barrels shooting ELDM factory 6.5CM.

Other JP owners report good submoa performance with Hornady Black.

Do I just need to shoot it some more and let it wear in? I have been told some barrels need to foul a bit more to get decent results.

Im new to precision gas guns so I figured I'd ask you guys what you think.

Thank you for your time!

What do the groups look like; any pictures? Horizontal or vertical group?

It could be a combination of more lax QC during this ammo crunch, not enough fouling in the barrel which largely depends on how many imperfections there are in the barrel (you'll need a borescope to check), or something like vertical stringing from heat build up affecting temperature sensitive powder (normally increasing pressure and velocity) inside the cartridge.

It could've been you pulling those two shots whether it's fatigue or the opposite (not warmed up). Example, vertical stringing not caused by heat build up could be inconsistent rear bag use while firing.

The 3 shot group touching with final 2 shots increasing group size makes me think that it may be ammo consistency or shooter error rather than barrel fouling/break in.

Something you can do is sort the factory ammo is measure overall length of each round and weigh them, then remove the extreme outliers. Ammo availability being what it is these days, you sometimes gotta shoot what you can get your hands on.

 

[SuperSneakySniper]

What do the groups look like; any pictures? Horizontal or vertical group?

It could be a combination of more lax QC during this ammo crunch, not enough fouling in the barrel which largely depends on how many imperfections there are in the barrel (you'll need a borescope to check), or something like vertical stringing from heat build up affecting temperature sensitive powder (normally increasing pressure and velocity) inside the cartridge.

It could've been you pulling those two shots whether it's fatigue or the opposite (not warmed up). Example, vertical stringing not caused by heat build up could be inconsistent rear bag use while firing.

The 3 shot group touching with final 2 shots increasing group size makes me think that it may be ammo consistency or shooter error rather than barrel fouling/break in.

Something you can do is sort the factory ammo is measure overall length of each round and weigh them, then remove the extreme outliers. Ammo availability being what it is these days, you sometimes gotta shoot what you can get your hands on.

Thanks for the replies everyone!
In my cases, it's not the last 2 that open it up, that was poor wording on my part. The flyers appear randomly. Sometimes it's the 2nd shot, sometimes the 4th etc... And I cannot discern any vertical vs horizontal stringing. Strange as it is, it just opens up wider in both regards. I also switched back and forth between shooting the Lapua vs the Black, the Black just underperformed each time. Weirdest thing.

I've got a pair of pics, the better group is the Lapua, the wider group is the best Black group I could manage (about 1.1moa).

I guess one more thing I could mention was, it was pretty gusty out that day. Much windier than I'd like to be zeroing a gun. Every single one of these shots I had to wait untill the wind died down to pull the trigger, so some inconsistency could be because of that. Though I figured it would affect both loads evenly.

You guys think there is any chance the groups could settle in with another 50 rounds through the barrel? Or would pursuing good Hornady groups just be a waste of time/money and I should just buy the Alexander Arms from here on out?

 

[Tonsofguns]

Your shots are very indicative of variable winds.
Hence why I only shot groups for accuracy indoors or very low wind. Even if you wait out the wind where you are shooting, you might have a little bit of wind between you and the target

 

[Snuby642]

In my 6.5 grendel the hornady custom 123g sst shoots better than the black box.

The gold box has gone just under 1 inch some days and the black box is only usefull to get fire formed brass for my gun.

They all shoot different.

The custom sst hornady is the best factory ammo in my gun so far.

 

[SuperSneakySniper]

Huh, interesting... Well, i'll try and get some more shots thru it with the Black on a day that has less wind. I know the Alexander Arms shoots well so I can keep that in my back pocket, but Hornady is surely more economical. I'll try SST too if I ever find any.
Im lucky if I find any ammo at all though.
Thanks for the input.
I'll update if I can!

 

[diggler1833]

Very, very few barrels shoot most factory loadings the same. Yours seems to have a pretty apparent preference for one of the two loads put through it. You are very lucky in that you found a load right off the bat that shoots 1/2 - 3/4 MOA in a gas gun. You can either beat yourself up trying to get the Hornady ammo to shoot, or you can buy whatever AA ammo you can find and have many more fun days at the range.

Congrats on the shooter.

 

[Evintos]

If you just showed me this picture without any description, I would've assumed 2 different groups. Looks to be about a 0.6-0.7" space in between the centers. The difference between would've been two different powder charges as well as the top group being affected by inconsistent seating depth or strong gusts of wind.

Since you said it was a fairly gusty day, the wind is likely the culprit for the horizontal. However for it to affect vertical, that's only likely if it's also around a 6 o'clock wind (tail wind). So basically strong gusts of wind from roughly 4-7 o'clock could account for both the vertical and horizontal dispersion.

 

[SuperSneakySniper]

View attachment 7612191

If you just showed me this picture without any description, I would've assumed 2 different groups. Looks to be about a 0.6-0.7" space in between the centers. The difference between would've been two different powder charges as well as the top group being affected by inconsistent seating depth or strong gusts of wind.

Since you said it was a fairly gusty day, the wind is likely the culprit for the horizontal. However for it to affect vertical, that's only likely if it's also around a 6 o'clock wind (tail wind). So basically strong gusts of wind from roughly 4-7 o'clock could account for both the vertical and horizontal dispersion.

Interesting you say that, gusts were right at 7-8 o'clock. There was never a moment of "no wind" but I did my darnedest to take advantage of the precious few moments of "as little wind as possible" between the stronger gusts. I will make SURE to make my next range outing on a windless day!

Very, very few barrels shoot most factory loadings the same. Yours seems to have a pretty apparent preference for one of the two loads put through it. You are very lucky in that you found a load right off the bat that shoots 1/2 - 3/4 MOA in a gas gun. You can either beat yourself up trying to get the Hornady ammo to shoot, or you can buy whatever AA ammo you can find and have many more fun days at the range.

Congrats on the shooter.

Also a great point... Thank you for the input!

I'm glad that my worries of having a "bum barrel" aren't true. My OCD brain was beggining to suspect I screwed it up during the break-in process or something lol.

Regardless, as far as finding ANY decent grendel ammo, I'm looking everywhere with no luck, and have very few oppurtunities to actually get my hands on some. So I've decided I'll buy whatever comes my way and just shoot it lol. I'll save any AA ammo I find for my local gas gun match!

Currently I have one last box of Black remaining and that's it. If I find any other boxes, I'll set out on another range trip and post my results.

 

[Dryan910]

I’ll second the Hornady custom SSTs. My 18” JP loves them.