Working on a new load .308

[JonProphet]

I'm trying to get my load down but I think I'm about ready to change from IMR4064. Keep in mind, this is a new rifle, r700 blue printed, squared, everything. Also, my chamber is cut short. Instead of a 2.8 coal, I have to run under 2.75. Here is my load data.

.308 Lapua Brass. (new unfired)
41.7 Grains of IMR4064
Sierra Match King 175gr
COAL of 2.80 to 2.803 (which probably jammed the bullet in the lands)
CCI magnum large rifle primers (last 130 or so, after gone, I'm probably going to move to a match normal rifle primer)

After a match (I ran a bore snake through after both stages) I ran a Chrono and come up with the following velocities:

1. 2640
2. 2714
3. 2689
4. 2663
5. 2690
6. 2705
7. 2680
8. 2722
9. 2657
_______
Avg of 9 2684

Am I not looking for a swing of about 20 FPS maximum? I am double checking my loads before seating the bullet. I'm checking my scale against a known weight, a 55 grain Sierra Game King .224 projectile, about every 2 to 3 rounds. If I don't get 55 grains, I take off and let it fall to zero, wait a second or two and zero out. Then place the .224 on the scale again and if I get 55 grains, I re-weigh the charge. Add or remove and re-weigh again. I'm doing a mild crimp. I'm also using CCI Magnum Large rifle primer (I'm down to my last 130 or so of these).

I think I would like to try some of the following powders: Vit 135, Vit 150, Varget and a buddy has real solid luck with AR Comp. Out of all of those I know where there is 3 pounds of AR Comp.

Do I need to get new data after I adjust my COAL? Do I need to lower my powder charge to find a sweet spot that doesn't swing so bad? What amount of change should I decrease by? 40 grains? 40.3? I understand I'm probably going about this the wrong way by not starting lower. I did get to peep at a Sierra loading manual and they say the maxium charge is 42.6 of 4064 if memory serves.

Let me know if you have any questions or comments. Any advice is greatly appreciated.

-JD-

 

[Broom_jm]

You might try some H4895. I shot a group that was just under an inch at 275 yards, with the 155gr A-Max.

Below is a 100-yard group my son shot on his 18th birthday. This gun and load has delivered groups under a half an inch at 100 quite a few times.

 

[j706]

Seating depth could be your fps variation

 

[Leo]

4064 is a VERY good powder for .308. Way too many people have won National events at Camp Perry with that powder to say other wise. I plugged the 10 ring at 800, 900, at 1000 yards with the 175 MatchKings on a regular basis (Master Level) with the 175 Sierra, it is a good dependable bullet.

QUIT zeroing your scale between powder throws. 41.7 or 42 grains, the exact weight is not nearly as important as the fact that they are all the same. If your scale is Mechanical, make sure the pivots are clean and make sure it repeats. If electroninc, if it does not repeat, send it for repair. At that accuracy level, air movement makes a problem. Get a cardboard box that protects both ends, the top and and back from air movement if there are HVAC registers nearby.


I would recommend ditching the magnum primers and trying regular rifle primers.

"Probably jamed into the lands" is definately a problem. You have to KNOW where you are in relation to the lands. You can develop a load for a bullet jamed into the lands like benchrest guys, OR you can develop a load for a regulated length of jump. It is not the same. You need to get a stoney point measuring system. That company has been bought out by Hornady, the last I knew. Measuring OAL is no where near as important as measuring the distance from the ogive major diameter to the lands. Sinclair International also has systems for precisely measuring bullet to land relationship.

Case prep makes a difference at your level. Trim length, flash hole uniforming and weight matching cases are needed if you really want a 20 extreme spread (which is a 10 standard deviation, darn tight specs) If you are only shooting off bags at 100 or so yards, three or four times that tolerance will probably be perfectly acceptable.

Good Luck

 

[kennedy759]

check out H4895 with 168 gr smk, I have shot some 5 shot 100 yd .4inch groups when I do my part out of a rem 700 varmet

 

[sloughfoot]

You say nothing about group size. And distance you are shooting at. I think I know, but you don't say it out loud in this post.

IMR 4064 is absolutely, without question, the best powder behind a 175 in .308. The gunsmith that cut your chamber short did not do you any favor. IMO.

Lapua brass is not a step up. Everybody on the internet thinks Lapua brass is perfect. It isn't. It is very heavy. Weigh your Lapua brass. The deviation in weight from piece to piece will shock you. Winchester commercial brass is far better for long range.

Get rid of the magnum primers. they are not helping you. Your speeds are kind of high for a 175 bullet. Approaching dangerously high speeds. I blame the magnum primers and the heavy Lapua brass. If your primer pockets don't hold the primer after just a couple of firings, that should be telling you something too about the pressures you are making.

If you want to learn to load for long range, I am always ready to help. I have made the offer before, it is real. Do you still have my spare powder measure?

One last thing, stop crimping match ammo. Uniform neck tension is good enough.

 

[JonProphet]

Thanks for the help guys.

The magnum primers were a mistake I made when I first started loading. I'm about through the 1K box and will be moving back to a BR primer. I've forgotten more times than 1 that I'm using magnum primers.

The smith I had do my gun comes highly regarded in the area (and some not so local) by many many shooters. He's a shooter himself. He recommended using the Lapua brass. He also said that his gun is for the most part identical and he recommended some powders. I don't mind sticking with the 4064 if I can get some consistency. I can get it pretty easily locally.

I'll stop crimping my brass. I put a slight crimp on the last load work up I had and immediately saw a better spread. Granted that was my old work up.

As far as the primer pockets, I've only had issues with the pockets after a pretty high over pressure situation. At lower levels, the primers are fine.

As far as distances, I did a 1K match and the gun shot well, I didn't. After the match we did some 100 yard work ups and also before it I did some 300 yard work ups.

I know I'm more than likely going about this the wrong way, but I'm getting advice from every direction and I have to select the advice (I trust Slough) more than most. I just hate to bug him so much! =) As far as the powder measure, the last time I was over I returned it.

Question, how much a deviation would one expect to see if the charge is .1 over/under?

Slough, if you need any dimensions, please let me know.

-JD-

 

[Yeah]

Question, how much a deviation would one expect to see if the charge is .1 over/under?

Nothing. There are enough variables inherent in the system to obscure a 0.1 grain variation. But you'd have to be confident the 0.1 grain you are seeing is a 0.1 grain in reality.

Eley isn't weighing charges...

 

[JonProphet]

Lapua brass is not a step up. Everybody on the internet thinks Lapua brass is perfect. It isn't. It is very heavy. Weigh your Lapua brass. The deviation in weight from piece to piece will shock you. Winchester commercial brass is far better for long range.

Weighed 95'ish pieces. Most hit the 173.5 grains, but the bottom end was 172.0 most were within +/-.5 grain. Almost half was unfired, all was chamfered. Is that good?

I've heard Lapua lasts longer and I was told to use Lapua.

-JD-

 

[indyjohn]

JonProphet - you've got most of the smart Highpower guys in one room talking about your loads. Be certain to take advantage of that privilege.

 

[JonProphet]

"Sinclair International also has systems for precisely measuring bullet to land relationship."

Is this what you are referring to?

Sinclair Chamber Length Gage | Sinclair Intl Caliber (xzzx308)

Tonight I loaded some more up. Trying to keep my mind off other things. I loaded up 39.5, 40.5, 41.7 and 42.5. 5 rounds each. I'll go punch some paper at 100 yds. I'm hoping I can get a rest or vice so I can get true groupings. I ditched the magnum primers and loaded up with Winchester standard primers. All still with 4064. No crimping. Case Length is still under 2.015 and I bumped the shoulders back to +.001 or +.0015.

Thanks for all the support guys.

-JD-

 

[indyjohn]

I believe Leo is referring to this: OVERALL LENGTH GAUGE | Sinclair Intl

 

[Leo]

Indyjohn is right, he is showing the chamber measure system I like. One of the features I like is that I can use the exact bullet I will be using in my loads in the case adapter. You also need a way to measure the ogive to base measurment. That same line of tools has adapters that clamp on your dial calipers. The tools are easy to use and gives good, repeatable measurements.

 

[sloughfoot]

Hold hard Jeremy. No need for a vice or rest unless you are going to compete with a rest or vice. I'll show you how as long as you have a front swivel stud for a sling.

 

[ScouT6a]

A .308 load that gave me good results was:
Lake City brass
CCI large rifle primer
168 grain Sierra Match King
42.5 grains of Winchester 748

In my Ruger 77 MK II VBZ this load would print 4" groups at 600 yrds and 8" groups at 1000. I seated my bullets .002" off the lands.
That was loading at a rate of 400 rnds/hr on a Dillon 550.

 

[JonProphet]

Got to the range tonight. Had a good time. Finally getting some good results. Without further ado......





Thanks.