Load development question..what next?

[smallbutfierce]

So I have been working on a load for my 308, 208 amax, rl-17, br2 primers. I worked from 46 to 49 grains. No pressure so I loaded up 5 of each working from 49 to 49.6. The sd and es were smaller with the higher loads but groups were more spread out. I have no signs of pressure yet, but I am running out of room in the cases. Should I load up and try to find the next node? How far are nodes from each other usually? I am running 2600 fps at 49, and that is the min speed I want.

 

[smallbutfierce]

So without any feedback I loaded up 6 of each 49.5, 49.7, 49.9, 51.1. I shot 3 shot groups this time to eliminate the chance for me to mess up the 5's. 2 groups under 1" with 49.9, sd 8, es 20, 2624 fps ave. Sounds like I have a winner. 50.1 opened up a bit, both on paper and on the chrono. Thinking anything more would start to get sticky, especially in the summer. The bullets are right on the lands now, gonna try backing out a little bit to see if that improves anything.

 

[Reynolds02]

ok, if you have found the powder and amount, next play with the seating depth. I'd say start right on the lands where you are and shorten them up in .005" increments til you are 20-25 thous. off. You should see a definite answer to where the gun likes it. After that play with a couple different primers to try helping the es/sd...good luck

 

[Bart B]

Real slow powders tend to produce erratic accuracy at max loads, at least in my opinion. Their pressure curves are not all that repeatable from shot to shot even with decent velocity numbers. This is often the compromise folks have to deal with to get the extra velocity they produce.

When heavy bullets were popular in the .308 for long range competition, 48 grains of IMR4350 was "the" load with Sierra's 200-gr HPMK bullet; won a lot of matches and even set records. But muzzle velocity in a 26" barrel was about 2500 fps. With that 208 AMAX, I suggest 47.5 grains of IMR4350 but you'll probably not get over 2500 fps.

It's also best to measure accuracy by the largest groups shot with a given load. That's what you can count on all the time. Those tiny groups with a given load only happen once in a while. With the exception of Berger's VLD bullets, most shoot more accurate when gently pushed into the lands when loaded.

 

[smallbutfierce]

I understand the compromise with this combo. I just thought I would give it a try while practicing loading techniques. I started reloading right at the beginning of the component shortage and I couldn't get a hold of the usual suspects like varget and 175 smk's. So this is what I have to work with, and I find shooting much more enjoyable now that I am working on loads and shooting skills.

 

[CB11WYO]

...next play with the seating depth. I'd say start right on the lands where you are and shorten them up in .005" increments til you are 20-25 thous. off. You should see a definite answer to where the gun likes it....

This is exactly what I would do next as well. I seat my bullets .010" off the lands until I find a powder charge that performs well. Then start fine tuning with the seat depths, it can sometimes make a big difference.

 

[smallbutfierce]

Update: It turns out that the temp sensitivity myth isn't a myth. Last tested at 35* F, no pressure. Today it was 65* F in the sun and not only did I get 2700 fps, but stiff bolt and ejector marks. On a positive note: Every single charge I tested with my rl15 175 match load was sub moa. So I guess I don't need to worry about not being able to get anymore 208's.

 

[MudRunner2005]

Man, I wish I could help, but I don't shoot any of the Hornady bullets. I do have a rather nasty load for the 210 Berger VLD's if you are interested, let me know.

 

[Bart B]

Update: Today it was 65* F in the sun and not only did I get 2700 fps, but stiff bolt and ejector marks.

That's proof your load's too hot. Peak presures are probably well over 65,000 CUP (80,000 psi); what proof loads produce. Accuracy will be way lucky, at best.

 

[MudRunner2005]

That's not necessarily true.....My STW loves the 180 Bergers, and my load isn't very hot at all....But the bolt was hard to open on some, and not stiff on others. Then I looked at my brass and I realized that some of them were pretty well-worn and in need of replacement. So that could also cause a stiff bolt, from my experience.

 

[Bart B]

That's not necessarily true.....My STW loves the 180 Bergers, and my load isn't very hot at all....But the bolt was hard to open on some, and not stiff on others. Then I looked at my brass and I realized that some of them were pretty well-worn and in need of replacement. So that could also cause a stiff bolt, from my experience.

Fact:

Cartridge brass starts to extrude back into bolt face cutouts at about 65,000 to 70,000 CUP.

 

[MudRunner2005]

I was agreeing with you, but I was also saying that that isn't always necessarily the only cause of a stiff bolt or tight chamber where the brass doesn't want to release...Sometimes worn brass, or cracked brass can cause that, too. Sometimes the brass cracks from wear & tear, sometimes from overpressuring your load.

 

[smallbutfierce]

I have aborted the 208's for now. And I have come to the conclusion that my 308 is no camaro, so to speak. Found a 175 match burner load that moves at a humble 2575fps, but makes a ragged hole and has been producing really low es. Going to try the 185 Berger next, more hunting oriented. Bart B, what powder do you recommend for the 185 vld? Saw an article where a guy swore by n150, but that's on the slow side and might give me the same trouble. Not many options right now but will jump on something if it turns up.

 

[Bart B]

Bart B, what powder do you recommend for the 185 vld? Saw an article where a guy swore by n150, but that's on the slow side and might give me the same trouble. Not many options right now but will jump on something if it turns up.

IMR4064. No more than 42 grains. That'll produce about 2550 to 2600 fps at maximum, safe pressures with a very repeatable pressure curve in 24 to 26 inch barrels.

Depending on how one tests loads for accuracy and how they interpret the results, several "most accurate" loads will surface for the same combination of bullet, powder, primer, case and barrel as tested by several people. How are you testing your loads for accuracy?