308 Match Load development: How many grains should I increase per test?

[adrenaline681]

For accuracy, I'd either go SMK, or the new eldm's are pretty good as well

I tried the Hornady 150gr FMJ with lots of different seating depths and powder loads. Most of them were between 1 and 2 MOA with the odd exception of 0.7 MOA and 2.6 MOA. But nothing that I could attribute to a specific load or seating depth.

I just purchased 100 168gr SMK and 100 168gr hornady A-max. will be testing these next with both varget and imr 4895.

 

[proxemus]

IMR4985 - 44.2Gr
Hornady HPBT steated to 2.8 OAL
Sig sauer brass
savage 10 ba - 1:10 twist 24" barrel w/ muzzle break
.3 moa at 100 all day long

(my hunting load)
IMR 4064 - 46gr
Hornady SST 150 GR steated 2.8 OAL
Lapua brass
savage 10 ba - 1:10 twist 24" barrel w/ muzzle break
BEST was 5 shots @ 100 .120, average .3

Benchmark - 46GR
Hornady FMJ 150gr steated 2.8 oal
Federal brass
savage 10 ba - 1:10 twist 24" barrel w/ muzzle break
.5 moa all day long. cheap ammo route

 

[GreenBob]

These will be my testing loads at 2.700" OAL:
41.0 gr
41.5 gr
42.0 gr
42.5 gr
43.0 gr
43.5 gr
44.0 gr
44.5 gr
45.0 gr
45.5 gr
46.0 gr

any reason why u r not loading them to 2.800?

If your rifle and you are capable, 168gr smk will do 1inch to 1/5 inch all day long.

 

[adrenaline681]

any reason why u r not loading them to 2.800?

If your rifle and you are capable, 168gr smk will do 1inch to 1/5 inch all day long.

2.700" is the recommended seating depth for the 150gr hornady fmj in Hornady's manual. altho when i was testing seating depths the 2.800" was a bit more precise. altho results were not very inconsistent, I shot each group twice.

2.800" looks very odd wasnt sure if it would be safe to load so far away from the cannelure and 0.1" away from Hornady's recommended OAL. Maybe next day I will load 50 bullets with 5 different loads (around 44gr which seemed to be the are where my groups were the smallest):
43.0gr (2 groups of 5 shots)
43.5gr (2 groups of 5 shots)
44.0gr (2 groups of 5 shots)
44.5gr (2 groups of 5 shots)
45.0gr (2 groups of 5 shots)

Let me know what you guys think...maybe you see something that I dont.

For the SMK I will seat to 2.800" or try to measure whats my headspace and place it 0.01" off the lands. Which is what I've been suggested by other people.

 

[The ROC]

^^^^
Fyi. Those are the groups I'm getting with my Cam Pro 147 gr with 40 gr of IMR 3031 plinking rounds.

 

[Ganderite]

2.700" is the recommended seating depth for the 150gr hornady fmj in Hornady's manual. altho when i was testing seating depths the 2.800" was a bit more precise. altho results were not very inconsistent, I shot each group twice.

2.800" looks very odd wasnt sure if it would be safe to load so far away from the cannelure and 0.1" away from Hornady's recommended OAL. Maybe next day I will load 50 bullets with 5 different loads (around 44gr which seemed to be the are where my groups were the smallest):
43.0gr (2 groups of 5 shots)
43.5gr (2 groups of 5 shots)
44.0gr (2 groups of 5 shots)
44.5gr (2 groups of 5 shots)
45.0gr (2 groups of 5 shots)

Let me know what you guys think...maybe you see something that I dont.

For the SMK I will seat to 2.800" or try to measure whats my headspace and place it 0.01" off the lands. Which is what I've been suggested by other people.

The longer OAL looks to be smaller, rounder group.

The OAL in the book is not a "recommendation". It is just a note as to the OAL they used for their rifle. You must set your own OAL to suit your rifle. The OAL they used means diddley squat. I wish they did not publish it.

To find your OAL load a round long - say 2.850" and chamber it. If the bullet comes out with rifling marks, seat another bullet deeper and try again. Each quarter turn of the seater stem is about 12 thou,

Keep doing this until a round comes out with no rifling mark on the bullet. Turn a quarter turn deeper and use that for your testing. The position of the cannelure means nothing - unless you are crimping for a semi-auto.

Once you find a good powder charge, experiment with slightly more and less OAL.

BTW, those groups are not very good. It is a poor bullet, probably the least accurate Hornady makes, but it should do better than that.

I ran a test with my SMLE using those bullets, and got similar groups.