A bit of load testing .308 win

[Varmartin]

Edit:...The Rifle used was my Sako TRG 22 .308win


Went to the range today with Dave aka.. `onehole`( not a member on here though) to do a bit of load testing.
I had made up my usual load of 155 Amax over 44 grns Varget in Lapua brass with a BR2 primer.

I had two lots of loads , same components but 2x different seating depths to test.

20 rounds loaded to SAAMI length of 2.810. Av velocity 2720fps
30 rounds loaded to 0.015 off the lands. Av velocity 2737

My old Musgrave chambered in 7.62 loved to be loaded at 2.810 so i was eager to test my TRG at the same length and also loaded 0.015 thou off the lands.

I think the test target tells a few stories...
As i also tested the velocity and `ES-extreme spread` from both loads
I am now wondering what you guys think would be the best load to test at longer range.

I am aware this is a `light` load for the .308/ 155 Amax but it is supremely accurate @100m

A...The 0.015 off the lands load, that shoots the tightest groups at 100m with an ES of 60 fps..or

B... the SAAMI load that gave bigger groups at 100m ,but gave an ES of 26fps .?

 

[Oliveralan]

Interesting results. From what I've tested with my 208gr and 178gr A-maxs, they like being close to the lands, im stilling tweaking the depth on my 208s but they seem to like about 5 thou off. A lot like Berger VLDs.

Try loading some heavier charges to see if that brings down your ES. 26 is the upper edge of an OK spread IMO, once you get over 25, the load isnt too good for LR hunting, where you have about a 10-20" target (depending on the animal).

Your ES may be caused by having too much empty space in your casings, how long were your "15 thou off the lands" loads? if they are significantly longer than the SAAMI case, that could explain it. Sort of like powder bridging but much less extreme, just causing non-uniform burning from case to case.

But looks like you got a shooter, very nice repeatable groups, now just need to cut a few fps off the ES and your good to go.

Oliver

 

[Varmartin]

Oliver, Thanks for your prompt post.

The COL was 2.280 to the ogive.

So 0.070` longer than SAAMI length. thus the extra space in the case as you said requires filling ..which is a good thing because as we have discused in another thread , I am looking for a higher velocity load any how...

My other rifle chambered in 6MM BR Norma likes to be run hot, with a case full of R15 or Varget depending on bullet....and those cases are possably 102% full..and the ES from those loads is usually less than 10 fps...

I have found `crunching` a few kernels works most of the time.

So it looks like i need to stoke the boiler in my .308 cases ....

 

[lever-hed]

The never-ending dilema… nice groups. (where is 2.810 from lands?, is the brass fire-formed?).

I would make 6 of each again, if you can improve on the ES.. if not, take both out further.. check SD.
Ps. Have you tried another primer?

 

[Varmartin]

2.810 is 0.110` from the lands, brass is 2x fired Lapua


Failed to getthe SD from the crono before it was packed away ,but did write down the velocities as i went ...

SAAMI load 2.810 to bullet tip
2721
2709
2737
2716
2720
2712
2730
2722
2705
2758

0.015 off the lands @ 2.280 to the ogive

2723
2738
2742
2717
2766
2717
2725
2749
2752
2738
2775

 

[lever-hed]

Hodgdon list a similar 155-gr projectile at max 47.0-gr Varget at 2909 fps (compressed load). For long range in this cal you will appreciate more powder.. increase charge as possible, and seat dept .010" from lands,checking for pressure spikes- and test some at .030" off. Some rifles like some "jump". Looks like a good start ..
Then move out.
Good luck

 

[Varmartin]

Thanks for all the good info guys..most appreciated ..

ps. forgot to add last time...yes i have tried another primer ..Fed gold medal match, same results but changed to the BR2 as I thought the harder cup might help with pressure as I increase the load from 46 grns.+

 

[alaska]

Looks like your at the lower end of OCW for the 155 MK........the upper end should be close to 47.0 grains of Varget.

I noticed Varget prefers CCI Br2 primers. I use WW brass.

Good choice of Powder for the 308 Win.

Don't forget IMR 4895 another outstanding powder with 155 gr in 308 win.

If your using WW brass I suggest around 47.0 with Varget using 150/155gr in the 308 Win.

 

[Varmartin]

Just an update...

I had the chance to crono some loads today..>>

46 grns Varget/155 Amax was producing an Av velocity of 2870fps from virgin Lapua brass/BR2 primers/26" tube.

The same load with 155 Scenars was 2896fps.......155.5 Berger VLD was 2838fps

Of all the loads i shot today 155 Amax are still the best and producing bughole groups...followed a close second were the Berger 155.5`s...

I am hoping this load will become more consistant with a lower ES ( 60fps today )when I reload the once fired brass.

I may switch back to the Federal GM match primers ..

Any body else find high ES in there velocity spread with virgin brass ?

 

[Mike6158]

There's a sticky at the top of the reloading forum (this one) that has links to two Excel spreadsheets that I built. One of them will let you input 10 velocity data points and it will calculate Low, High, Average, ES, Energy, and SD for the string.

For instance- using the velocities from your first group-

Low = 2,705
High = 2,758
Average = 2,723
ES = 53
Energy = 2,767
SD = 15.54

2.810 is 0.110` from the lands, brass is 2x fired Lapua


Failed to getthe SD from the crono before it was packed away ,but did write down the velocities as i went ...

SAAMI load 2.810 to bullet tip
2721
2709
2737
2716
2720
2712
2730
2722
2705
2758

0.015 off the lands @ 2.280 to the ogive

2723
2738
2742
2717
2766
2717
2725
2749
2752
2738
2775

 

[alaska]

47.0 Varget and 308 Win

I suggest 47.0 of Vaget using 155gr and WW brass.......with Varget I have had best results with CCI br2 primers.gun)

Lapua is excellent brass but WW brass I beleve has more capacity.

 

[Varmartin]

Thanks for the replies fellas, I willreport back when I have loaded another batch.

 

[groper]

ive found 45.6gr AR2206H (H4895) = 2950fps and very tight 1 hole groups using 155gr VLDs...

ES is a tad high @ 30fps, but im still tweakin it...

 

[alaska]

In the 308 Win for years back in the 80's and 90's Palma Match IMR 4895 was the powder to beat. The new then Reloader 15 was a contender....

Still a excellent powder for the 308 win

1992 Palma records - IMR4895 was the powder of choice for most folks. Charge weights varied from
44.3 to 45 grains with the 155 MK. Some folks threw charges direct from measures; others
weighed every charge to a +/- .05-gr. spread. Interestingly enough, the
powder lots had varying degrees of fouling. That's not surprising as IMR4895
is one of the `dirtier' powders on the market. Most folks didn't clean their
barrels during the day on the range. Others drybrushed after each, or every
other 15- or 20-shot stage. Many of the top scores were shot using IMR4895.

A good load is IMR 4895 @ 43.6 with 168 Sierra MK and Fed 210M in FC brass. This will duplicate the Federal Gold Medal Match load @ 2600 FPS.