Testing the 142 LR Accubond

[alf]

So yesterday the brown truck dropped off a few boxes of Nosler 142 LR Accubonds. I sat down and compared measurements from an older box of 140 VLD's.....

Berger:

1.395" OAL
.200" boatail length
.455 bearing surface

Nosler:

1.440" OAL
.240" boatail length
.525" bearing surface

After measuring, I threw 200 in the vibrator to give 'em a shiny new moly plating, then proceeded to load up a few for testing. Nothing elaborate, 52-55 grains of H-4831-SC, 3 shots for each, and seated them for a square mark on the ogive.

The platform is a S/S 700, 26" Bartlein 3B contoured 5R barrel, McMillan Sporter stock, and a NF 5.5-22x50 in Seekings rings & bases, weighing in at 10 lbs 12 ozs, chmbered in a 6.5x284 with a .290" neck, .188" freebore.




I set the target up at 270 yards and set up the bench, gun, and chronograph. Temp was 80 degrees, light swirling wind from any/all directions, and mirage up the whazoo. I shot round robin style, one shot at each bull at each charge weight, three times, keeping to 2-3 minute intervals per shot.





Nothing spectacular, but considering the conditions, it wasn't too bad, with 53 and 54 being under 3/4 MOA

Came home, cleaned the gun, and loaded up 30 with 54 grains, and seated them into the lands, to shoot them today at distance.

 

[alf]

So I got out to my "range" this AM, and set up the targets and steel. I backed off to 200 to double check my zero, and shot a decent 1 3/8" group, then moved back to 600.



I dialed in 8 1/4 MOA, knowing it was not enough, but I was hoping to print below the bull, so I could spot them better. The only problem with that, was the flies were drawn to my target so bad, I had 3 dozen moving bullet holes. So I drove down to check it out, and found this group:



Not too shabby, 4 1/2" exactly 12" low. I came back, dialed in two more MOA, and shot one on the steel: (top shot)

 

[North Idaho Hunter]

Are you going off brian litz published BC or noslers?

Great shooting!

 

[alf]

Are you going off brian litz published BC or noslers?

Great shooting!

Thanks.....

I didn't know Litz had tested them yet, and we figgered Nosler was stretching things.

More results coming shortly.......

 

[alf]

With the 600 yard results satisfied, I loaded things back up, and move on out to the 1000 yard mark:



By now the sun had popped out, the mirage was running a bit, and the wind had picked up to a quartering away direction. Took a WAG on the turret and hit the steel low first shot, but then proceeded to miss the next 2 or 3, and couldn't spot the impacts. Finally saw a hit low and right. Added 2 MOA of wind, and a couple three more on elevation, and promptly nail another plate twice in a row right at the top. Those two went 9 1/2":



Then I moved over to the paper target, and banged off three. Wind got me a bit, but they still went into 11 1/4". I still had 24 3/4 MOA on the dial.




I then took two clicks out, 24 1/4 MOA on the dial, and pounded one more back into the steel, **** near dead center.

 

[alf]

After I plug in all the info into JBM, I needed to drop the BC down to .550 to jive with my actual drops using 2980 for velocity:

Range - Drop

600 -9.7

700 -12.8

800 -16.3

900 -20.1

1000 -24.2

 

[stomp442]

Wow .550, I was expecting something around the .620 mark. How does these numbers compare with your Berger numbers?


Great write up on the testing by the way. You got a nice set up out there.

 

[alf]

I'm running 130 VLD's at 3150.

8.5 MOA at 600, and 21.2 at 1K. I've gone to 1350 or so w/ that load.

 

[stomp442]

Wow 3 MOA difference with a lighter bullet is impressive although not surprising since BCs are virtually identical. It would seem as though Nosler needs to go back to the drawing board with this one if all they can get is a .550 BC. That is no different than their CC bullet which has a Litz measured BC of .550 as well. An interesting test would be to shoot a custom comp bullet at those ranges and see if there is any significant difference.

 

[308175]

I'm guessing there is a flaw somewhere in the setup, zero, or other factor or miscalculation to come up with .550 for the 142 ABLR. That's lower than Bryan's value for the 129 ABLR. Same nose profile and boat tail profile while adding 13 grains is only going to make it stronger. Not weaker.

It should be around .605-.609G1. Still far from published but it's still a good number.

 

[7mmShooter]

When Bryan Litz was asked about them, he estimated around .62 G1 for the 142s FWIW.

 

[Greyfox]

I thought it ws interesting that the correction was made by lowering BC as opposed to velocity. My 26" 6.5x284 with a similar charge of H4831sc runs 2900-2950FPS. .550BC is way off the Nosler spec. I would have thought it would run closer to the Berger 140's.

 

[alf]

I ran 15 rounds over the Ohler last night for a 2967 average.

Heading out for another test.......stay tuned.

 

[BryanLitz]

What's your barrel twist?

These 142 LRAB's are long, like 1.450". If your 6.5-284 is pushing around 2900 fps and the barrel is a 1:8.5" twist (guessing, I skimmed the post and didn't see a MV or twist) then you could be seeing 6% or more BC loss.

This is what I found with the other LRAB's, the BC's are good, but you might need more than conventional twist to get it all. Even at 2900 from an 8 twist, the 142 LRAB is just getting an SG of 1.5 in standard sea level conditions, less in winter.

Remember you can still get great groups (precision) with bullets that are flying with marginal stability and depressed BC's.

I've got these 142's in the que to test soon. I'll shoot them from the 1:6" twist just to be sure we're seeing all it's got to show us for testing purposes. If you have a 1:8.5" twist, you won't get all the BC from these bullets unless you're high up in altitude.

You can run the Berger stability calculator to see where your stability will fall: Twist Rate Stability Calculator | Berger Bullets

Take care,
-Bryan