.308 workup, need help choosing

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jwrowland77

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Here's from a .308 workup I went and shot today. Having a tough time choosing which one I should look at a little deeper, or should I look at all 3 a little more. All 3-shot groups at 100 yards.

.308 Win
Sierra MK 155gr Palma
OAL 2.900
CCI 250
IMR4895

ImageUploadedByTapatalk1372537199.932644.jpg
ImageUploadedByTapatalk1372537216.889268.jpg
ImageUploadedByTapatalk1372537232.053349.jpg
 
You can cover all three with a dime? So what is your question? I would load up the load for the third target, shot it again and if the group held call it a day.
 
Muddydogs said:
You can cover all three with a dime? So what is your question? I would load up the load for the third target, shot it again and if the group held call it a day.
Click to expand...

I guess, should I shoot just the one or all three again. Should I go with heavier charge or lighter, or does it matter? Should I look at the way one groups as compared to another?
 
jwrowland77 said:
I guess, should I shoot just the one or all three again. Should I go with heavier charge or lighter, or does it matter? Should I look at the way one groups as compared to another?
Click to expand...
I myself would just shoot the last one. What are you looking for? For a hunting load all three are great, for 1000 yard match you might want to mess around a little more. The first target could be your best group depending on if you pulled the shot to the right or not. Truly for a hunting rifle all three are good. Wish my 7mm would group that well, best group was this morning at .6 inches.
 
I'm looking for long range match with this bullet.

Btw, on 7mm, check out my results from today for 7mm. 5-shout group covered by a dime.
 
If I was going to use those in a Palma LR gun match, I'd load in bigger batches and do some 10 round groups.

Then pick the best group, with the lowest spread in velocity, go out to 600 yards with it and see how it's holding up at Midrange.
 
You'll want the velocity of the higher charge for long range with the 155 Palma, assuming its accuracy verifies over multiple 5-shot groups at 100 & 300 yards.

JMHO
 
Normally I'd want the highest velocity, too.

But the smallest variation in velocity is more important to me than highest velocity in a 1,000 yard match load. Perhaps he'll find that the highest velocity also has the least variation. But that's not always true. Often times a charge just a bit below maximum will deliver the most consistent velocity.

At 1,000 yards large spreads in velocity will cause the shooter to bleed points in a match.


And yes, I would measure velocity of 10 round strings.
 
I don't disagree about wanting the lowest possible ES, but a 155 Palma needs to be moving as quickly as feasible to make it to 1000.

Also, the highest charge pictures is all horizontal. Granted 100yd groups don't tell much, but I'm inclined to think shooter technique vs. velocity variances.

Confirmation at distance, with more groups of more rounds, is necessary.
 
Thanks guys. I'll have to load up some more and do groups of 10 at various yards.

I've never competed in anything except Steel Challenge so doing long range comp will be a new experience.

The 44.5 charge is over max in the Sierra manual but under max in a couple other manuals. At 45 grains, the spreads started to open up, which my mentor had told me awhile back, that means its getting close to over-pressure. I looked at the cases and the primers looked good but the spreads opened up starting at 45.

I'll have to do 10-shot groups at 44.5, thinking about 44.2 as well and trying that charge out to see if the horizontal spreading decreases. My technique is pretty decent. Same day with my 7mm RM I had a .250 spread with 5-shot group at 100.

I'll make 10 each of 44.2 and 44.5 and see how that works out.

Thanks again guys for the advice. Much much appreciated
 
I would tend to favor the third charge (44.5) as well. When groups are close in size for load testing I tend to favor the one with the least vertical variation. Vertical stringing seems more reflective of barrel harmonics and reflects what load your barrel prefers whereas horizontal spread is more likely to be a result of the shooter (trigger pull). Also, as others have said, for 1000 yard shooting that extra velocity will help with a 155 grain bullet. If your rifle shoots the higher velocity load better and there are no signs of pressure its a winner I would say. Id probably shoot some more 5 or 10 round groups just to confirm the results
 
Last edited:
Third group load, I would do a ten shot group. Actually I might even go up another half a grain and see if the group degrades. Then choose which one to 10 shot group.
 
With a 155gr Sierra bullet Hodgdon lists a charge range of IMR4895 of 43.5gr to 47.5gr. As your charge weights increased the group size shrunk so I would increase the charge weights 1gr to 45.5gr, 46.5gr and then 47.5gr unless accuracy falls off before you get that high. Your first 2 loads seem to be below the min set by Hodgdon.

Once you find the best group fine tune the load using .5gr charges above and below the best group and see if you improve even more.

*EDIT*
It seems you were writing the same time I was but I took much longer. Since accuracy fell off above 45.0gr I would stick with the 44.5gr load since that was the tightest.
 
Load up 10 of the best 2. Shoot them slow enough for your gun to stay cool. 3 really isn't enough to rule out luck of them going to the same spot
 
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