Load work up?

[silentnswift]

I'm trying to do some load workup for a 700 sps tactical .308. I used new lapua brass, neck sized only. Imr 4064, 175 smk and fgmm 210 primers. I started at 38 grains and worked up to 43 in .5 increments. I loaded one round each weight and shot them at 105 yards. It's the farthest I can get right now. I ended up with more of a group than a ladder test. 38-39 were less than 1/2 inch vertically. 41.5-43 were about 1/2 inch vertical. I seen no pressure signs. Where should I go from here. Load up 5 rds from 41.5-43 and shoot for a group. I have a chrony on the way but it'll be a week or so

 

[ChrisGarrett]

For a box of 50, I'd load 10 rounds at X, 10 rounds at Y, 15 rounds at Z and the final 15 rounds at A and shoot your groups of 5 and see what you see.

Don't worry about vertical at 105 yards, but look for group size. That gives you 10 groups 2, 2, 3 and 3, so you should start to get a better idea. Maybe go 10 at 38gr, 10 at 40gr, 15 at 41.5 and 15 at 43gr, or any combination that you see fit.

Chris

 

[damoncali]

You have to shoot groups. The more the better. One round per load will tell you nothing. Depending on how lucky you are, it takes 50-100 rounds worth of 5 shot groups to come up with a load that you can be confident in. There is no shortcut, despite what you see written on the web about ladders, OCW, and the like. There's no cheating statistics. You speed things up a little if you have a good idea what loads might work. For example, you'd be nuts to not try something bracketing 39 grains of H4350 with 107's in 6XC, but you still won't *know* it works unless you shoot a few groups. 4 loads X 3 5-shot groups each = 60 rounds. Just the way it is. There are a LOT of people tricking themselves into thinking they have a better load than they do.

You can also shorten up the process if you are willing to settle for a "good enough" load rather than the best load. If you need 1 MOA, and two or three groups of your first load are under MOA, stop. You're done.

 

[oldfatguy]

OCW method works really well.

OFG

 

[29aholic]

OCW method works really well.

OFG

Yep saves time and components

 

[Darkside-Six]

Agreed. if you can only shoot at 100 then do an OCW test. for ladder tests you have to be at least 250 yds. I get better results from an OCE test fired in round robin types.

 

[KYpatriot]

D-6 is right, shoot an ocw round robin style ad go from there. Don't rush it.

 

[Twoboxer]

Another vote for OCW here.

And a reminder that Federal Gold Medal Match 175gr ammo uses 41.75gr IMR4064. You're using Lapua brass, so the charge to duplicate may vary a bit from that number.

 

[silentnswift]

I get that the ladder test won't be very accurate at 100 yds. I was more checking for pressure signs to get a starting point. I've seen most people seem to have good luck around 42 grain. I've heard that fgmm is anywhere from 41.7 to 42.8. With the ocw test you look for which groups the best?

 

[Darkside-Six]

I get that the ladder test won't be very accurate at 100 yds. I was more checking for pressure signs to get a starting point. I've seen most people seem to have good luck around 42 grain. I've heard that fgmm is anywhere from 41.7 to 42.8. With the ocw test you look for which groups the best?

That is somewhat true but it all depends on how long your barrel is and what the twist rate is. I also shoot 175SMK's with IMR 4064.

my go-to load is 43.5 gr which gives me an average MV of 2700 out of a 1/12 Schneider barrel. The only difference is that I don't use Lapua brass, I use Lake City LR brass.

Start at 41 grains and work up to the max in .2gr increments.

 

[Twoboxer]

. . . With the ocw test you look for which groups the best?

The method looks for a node(s) at which barrel harmonics allow bullets to exit the barrel on the same trajectory to the same POI even with small variations in powder charge. The full logic and instructions are here: OCW Overview - Dan Newberry's OCW Load Development System

 

[LukeNCMX]

Current 175 FGMM does not use a 41.7 grain charge of IMR 4064. I just shot a new case of it three months ago and I was getting about 2600 MV.

I was shooting them back to back with my own loads:

175 SMK @ 2.800 COAL
41.7 Grains IMR 4064
FGMM 1xfired shoulder bumped brass
Federal 210M Primers

That load was getting me about 2560 MV over 150 rounds.

All those over a magentospeed v2.