Development - follow the groups, or follow the velocities?

[fattybinz]

Developing a load for a 223 Rem. Bighorn Origin, 27" Blackhawk Barrel. Tried a few powder and bullet combinations. TAC and Hornady 75 gr Match BTHP showed promise, so that is what I'm developing with. I'm testing chargeweights first. The lighter chargeweights shot the best groups, but had pretty horrendous ES and SDs. The heavier chargeweights shot terrible groups but had velocities that were great. As I move on to seating, do I 1) follow the targets/groups, or 2) follow the velocities and then use seating depth to tighten up the groups? I'm going to be commonly stretching this rifle to 1000-1300 yards, so I'd of course like consistent velocities, and I wouldn't mind choosing going with the faster chargeweights to enjoy those ~3100 fps speeds.

In case it matters, this is using x2 fired brass, all sized to give me .001-.002" headspace. Sized with a SAC modular die with a mandrel that gives me .001" neck tension. These were loaded .045" off the lands.

Below is a table with each chargeweight I used, the group size, the mean radius of the group, the average velocity of each group, and the ES/SDs. These were all shot at 200 yards. Do more weight testing, or move on to seating?

 

[Clancy]

I’d go to 2 or 3 thousandths neck tension, run a seating depth test FIRST, then work on the powder.

I have no idea how you got a 75 grain bullet to 3165, but if you enjoy having fingers and eyes I’d cut that out.

Even your starting loads are crazy velocities.

Always follow the groups- though, you need to go back to the drawing board with this one.

You actually started above any max load I could find.

My head hurts.

 

[Straightshooter1]

I agree with Clancy . . . it looks to me like very hot loads, even with those lighter loads.

What COAL are you loading them to?

How many shots for your groups and velocity data?

Developing a load for a 223 Rem. Bighorn Origin, 27" Blackhawk Barrel. Tried a few powder and bullet combinations. TAC and Hornady 75 gr Match BTHP showed promise, so that is what I'm developing with. I'm testing chargeweights first. The lighter chargeweights shot the best groups, but had pretty horrendous ES and SDs. The heavier chargeweights shot terrible groups but had velocities that were great. As I move on to seating, do I 1) follow the targets/groups, or 2) follow the velocities and then use seating depth to tighten up the groups? I'm going to be commonly stretching this rifle to 1000-1300 yards, so I'd of course like consistent velocities, and I wouldn't mind choosing going with the faster chargeweights to enjoy those ~3100 fps speeds.

In case it matters, this is using x2 fired brass, all sized to give me .001-.002" headspace. Sized with a SAC modular die with a mandrel that gives me .001" neck tension. These were loaded .045" off the lands.

Below is a table with each chargeweight I used, the group size, the mean radius of the group, the average velocity of each group, and the ES/SDs. These were all shot at 200 yards. Do more weight testing, or move on to seating?

View attachment 1668357

 

[fattybinz]

I agree with Clancy . . . it looks to me like very hot loads, even with those lighter loads.

What COAL are you loading them to?

How many shots for your groups and velocity data?

CBTO is 1.822". 5-shot groups.

 

[fattybinz]

I’d go to 2 or 3 thousandths neck tension, run a seating depth test FIRST, then work on the powder.

I have no idea how you got a 75 grain bullet to 3165, but if you enjoy having fingers and eyes I’d cut that out.

Even your starting loads are crazy velocities.

Always follow the groups- though, you need to go back to the drawing board with this one.

You actually started above any max load I could find.

My head hurts.

Thought I was paying attention to pressure signs. In the higher 25gr I had some minor cratering. No bolt lift issues.

I did start with seating depth test to find a good place to develop the chargewieght in. Here was the outcome of that initial seating depth test. Didn't like being into or touching the lands.

Why do you recommend moving up to 2-3 thousands neck tension?

 

[Straightshooter1]

CBTO is 1.822". 5-shot groups.

CBTO doesn't tell me anything your cartridge configuration, since I don't know how your comparator fits. That's why I was asking for COAL, which is much easier to get an idea for your cartridge configuration. Just provide an average measurement.

 

[Webster]

Developing a load for a 223 Rem. Bighorn Origin, 27" Blackhawk Barrel. Tried a few powder and bullet combinations. TAC and Hornady 75 gr Match BTHP showed promise, so that is what I'm developing with. I'm testing chargeweights first. The lighter chargeweights shot the best groups, but had pretty horrendous ES and SDs. The heavier chargeweights shot terrible groups but had velocities that were great. As I move on to seating, do I 1) follow the targets/groups, or 2) follow the velocities and then use seating depth to tighten up the groups? I'm going to be commonly stretching this rifle to 1000-1300 yards, so I'd of course like consistent velocities, and I wouldn't mind choosing going with the faster chargeweights to enjoy those ~3100 fps speeds.

In case it matters, this is using x2 fired brass, all sized to give me .001-.002" headspace. Sized with a SAC modular die with a mandrel that gives me .001" neck tension. These were loaded .045" off the lands.

Below is a table with each chargeweight I used, the group size, the mean radius of the group, the average velocity of each group, and the ES/SDs. These were all shot at 200 yards. Do more weight testing, or move on to seating?

View attachment 1668357

Check out the 223 load maps on this site. The variation in group size with small powder increases doesn't look good. Do you have proper twist for heavy bullets. The factory twist are probably for about 55 gr. bullets? I never worried about speed when working up loads, but I knew I was about 1 gr under max. Someone else can comment on whether the ES means the wrong powder. The ES are all over and don't show a pattern. Maybe the small one would get bigger with more shots. I have 2 chrono's but I pick a load by small and round. I usually pick a powder by looking in the loading manuals and pick 3-5 that show the highest fps. Buy 1 or two at a time and try them. My rifles are for GH hunting so if a powder looks a little worse than another I can still shoot it to get rid of it. I think the Sierra website has an ideal twist calculator for different bullets

For some reason I have always recorded the vertical and horizontal distance on each group and not max diameter. The results are interesting. I always hold for the center of the bull at 100 yards. The horizontal is almost always .100" wider than tall. I assume that gives me the wind effect.

 

[memilanuk]

Do you have proper twist for heavy bullets. The factory twist are probably for about 55 gr. bullets?

He's using a custom action and barrel.

 

[Clancy]

He's using a custom action and barrel.

He’s also running pretty dang close to 22 GT speeds.

I run on the ragged edge a LOT and I can’t fathom 3165 with a 75 gr in a 223.

I know what you meant but just wanted to say that again.

 

[fattybinz]

Do you have proper twist for heavy bullets. The factory twist are probably for about 55 gr.

Twist is 1:8. A quantum app tells me I'm stable with a stability factor of 2.50

 

[fattybinz]

He’s also running pretty dang close to 22 GT speeds.

I run on the ragged edge a LOT and I can’t fathom 3165 with a 75 gr in a 223.

I know what you meant but just wanted to say that again.

What velocities should I be looking for (or that you consider max) for this long of a barrel?

 

[Clancy]

What velocities should I be looking for (or that you consider max) for this long of a barrel?

Ehhhh 2850 or so if you don’t have any bullet below the neck shoulder junction.

Less than that if you do.

MAX.

 

[kyotekiller25]

I think around 3000fps with a 75g in a 27" bbl would probably be around max for most bolt actions. 3150 is a bit much in my opinion.

I'm right at 3000fps with 75g ELDMs and 24.7g N540 from a 28"/8T Bartlein, and that's an upper end load for this rifle.

Based off your powder charge testing, I'd be looking at around 24g personally. That's about right for velocity, and your groups are a lot better.

 

[NZ_Fclass]

I think around 3000fps with a 75g in a 27" bbl would probably be around max for most bolt actions. 3150 is a bit much in my opinion.

I'm right at 3000fps with 75g ELDMs and 24.7g N540 from a 28"/8T Bartlein, and that's an upper end load for this rifle.

Based off your powder charge testing, I'd be looking at around 24g personally. That's about right for velocity, and your groups are a lot better.

Agreed. I prefer a bit slower with Varget or H4895. for better accuracy in my rifle, and I avoid double base powders, due to the combustion temperatures and barrel wear in longer matches. Experimentally, I have achieved some ridiculous velocities with N550 and R17.with magnum primers. During this testing I also learned not to shoot across the bonnet (hood ) as the windscreen (windshield) developed a large crack!

But best of luck to the OP with a 223 out to 1250 yds., at any velocity.

 

[linebaugh]

Just to chime in on your loads. I ran 75gr ELDs at 3075 with a 223AI in a 30" tube. While that may not have been a max load it was no slouch

 

[CharlieNC]

If you still have the targets, measure the point of impact vs point of aim distance. There are numerous posts about ladder and ocw testing showing that you will find a charge weight zone with minimum change in poi. This is a reproducible node where smaller groups will follow. Minimum shots for maximum results.

 

[SKWERLZ]

I’d go to 2 or 3 thousandths neck tension, run a seating depth test FIRST, then work on the powder.

I have no idea how you got a 75 grain bullet to 3165, but if you enjoy having fingers and eyes I’d cut that out.

Even your starting loads are crazy velocities.

Always follow the groups- though, you need to go back to the drawing board with this one.

You actually started above any max load I could find.

My head hurts.

This!

 

[fattybinz]

Agreed. I prefer a bit slower with Varget or H4895. for better accuracy in my rifle, and I avoid double base powders, due to the combustion temperatures and barrel wear in longer matches. Experimentally, I have achieved some ridiculous velocities with N550 and R17.with magnum primers. During this testing I also learned not to shoot across the bonnet (hood ) as the windscreen (windshield) developed a large crack!

But best of luck to the OP with a 223 out to 1250 yds., at any velocity.

Thanks. I thought 1200+ wasn't a reasonable expectation but I did my fireforming and break in at a range with a 12" gong at 1220 and was surprised to hit it on my second shot. Probably a lot of luck getting as close to I did with the first shot. After that was able to hit it once every about 5 shots. That was also before any load development. I had plenty of elevation left in the scope, so who knows...going to try for 1500. It may take 40 shots, but I think it'd be fun. Ballistic calc says I can do it with max elevation plus a small hold over.

 

[memilanuk]

Better go buy a lottery ticket.

 

[NZ_Fclass]

Thanks. I thought 1200+ wasn't a reasonable expectation but I did my fireforming and break in at a range with a 12" gong at 1220 and was surprised to hit it on my second shot. Probably a lot of luck getting as close to I did with the first shot. After that was able to hit it once every about 5 shots. That was also before any load development. I had plenty of elevation left in the scope, so who knows...going to try for 1500. It may take 40 shots, but I think it'd be fun. Ballistic calc says I can do it with max elevation plus a small hold over.

Do go look at"Mark and Sam after work" on YouTube. An Aussie couple that shoot some real long shots.