I have been reloading for a little bit now and I might be doing something wrong with the Hornady ELD-Match 168 gr. Bullets as opposed to the Hornady 168 gr. BTHP Match that I have been exclusively using prior to the ELD-M.

The 168 BTHP hold sub MOA. The ELD-M are all over the paper.

Load data:
Bullet load (successful sub-MOA), Hornady #30501, 168 gr. HPBT,
Bullet load (UNSUCCESSFUL 4+ MOA) Hornady #30506, 168 gr. ELD-Match,
Winchester brand 308 brass,
46.5 gr. BL-C(2) powder (max load),
Remington 9-1/2 large rifle primer,
Avg. Velocity 2,699 ft/sec,
Extreme spread 35 ft/sec,
Standard deviation 12 ft/sec.

Firearm data,
DPMS Patern 308 AR type,
Black Hole Weaponry 24" pologonal rifled barrel wit 1:11 twist,
CMC 2+2 Match trigger,
Fired from an Atlas bipod on a sandbag at the rear for sighting the loads through the chronograph onto paper.

Atmospheric data:
70% humidty,
Barometric pressure 29.97,
Wind SSE at 3mph,
Elevation 1,250 ft,
Shooting orientation S-N,

When I use the Hornady 168 gr. BTHP (Hornady item number 30501) with the same exact load data, maybe a little slower by 30-40 ft/sec due to the sectional density and ballistic coefficient, the BTHP loads hold sub MOA at 100 yards. The ELD-Match are all over a 8" group.

I reload on a Rock Chucker, weigh every charge to .01 grain by hand on digital scale via trickle method with reweigh followup on ever charge. The only thing I can think I am doing wrong is the crimp strength or the bullet ogive to rifiling clearance is off a big difference compared to my success with Bullet #30501. I have loaded 25 of the "wingers" (bullet #30506) and assumed that I would get good data by setting the bullet depth to the same as I do the HPBT bullet, 2.795". The ogive on the "winger" is more gradual and probably resulted in a farther bullet jump than the successful loaded # 30501 bullet. I did now set the bullet to the ogive and the barrel rifiling. I would not imagine a bullet jump to the rifiling would make a huge difference so I am wondering why I would be clueless? Or...does the boat tail design of the ELD-M design vary to the point in difference to the regular HPBT Match bullet in that it doesn't like the hot load?

I'm hoping for some good input please. Its been since 1990 that I reloaded and
Had any problems with a load. And.... since I've loaded in the past month the few hundred #30501 HPBT Match to sub-MOA my practices have proved reliable.

welcome to AR. my best guess would be you need to drop the load a couple grains and work back up. the bullet jump to the lands do make a difference in most of my rifles. I have my OAL set to 2.81". My best loads were with H380 Starting 2grs under max. 3/8 to 1/2 in groups.
The only other thing might be the primer. I like CCI br2
Dave

You need to start load development from scratch as these two bullets are totally different. The ELD-M bullet has a much sharper ogive and therefore seating depth will be different. Your AR10 just might not like the new bullet either but some playing with it will probably give you an idea about that.

Thanks for the insight. These are rudimentary things that I need reassurance on. Thank you again.

An update for anyone interested.

I got the Hornady 168 gr. ELD-M dialed in to 1/2 MOA. Shot out to 1,050 yds. successfully 85% on 16" plate with 10 mph 90° cross wind.

Lapua Brass
CCI BR2 Primers
46 gr. BL-C(2)
168 gr. ELD-M
COAL of 2.795, Light crimp

I love it when a plan comes together.

Besides the 1/2 grain powder charge, what else was changed to get this load to work for you?

I was able to achieve the results by dialing the powder in and bullet jump set to 0.030".

my basic load pattern is
mid book load
-.025 to -.035 off the rifling for conventional bullets, -0.065 for monometal bullets. barnes type bullets, i go BACK ...

quote:

Originally posted by Ken M:
I got the Hornady 168 gr. ELD-M dialed in to 1/2 MOA. Shot out to 1,050 yds. successfully 85% on 16" plate with 10 mph 90° cross wind.

Lapua Brass
CCI BR2 Primers
46 gr. BL-C(2)
168 gr. ELD-M
COAL of 2.795, Light crimp

Exxxxcellent work. To be honest, if I started with 8" groups, I would have completely written off that bullet in that particular rifle.

I'm quite surprised how little tinkering it took to make a SIGNIFICANT difference in accuracy. Looks like you changed brass & primer, but used the same COAL and only dropped down 0.5 grains of powder.

So good for you! Persistence paid off.