Compressed loads for 308?

[fox]

Hi,

Im new on here but have been lurking for some time. I have just started shooting a Remington 700 VSF in .308 Win and I have been looking into some of the loads mentioned both on the 6mmbr home page and some here on the forum. The rifle is mainly intended for some target shooting at all ranges up to and including 1000 yards,this will be very occasional at this range). As is reccomended in numerous places, I have been working up loads using the 155gr Lapua Scenar using Lapua Brass, CCI BR primers and im in the process of trying out N140, Varget, H4895 and some others too. I notice that many of the loads suggested for this calibre, bearing in mind you have to push the 155 pretty fast to ensure it is stable at 1000yards 2850-2900fps I beleive, are using what look like very compressed powder charges. 46 gr of Varget in my cases dont leave much room for a bullet in the neck and even though this isnt a problem at 1000 yards sngle loading, I would need to heavily compress this charge to get it down to 2.800 OAL as some of the shooters are doing.

SO my question is this, I realise normal procedures apply to working up loads, going up in weight gradually and doing the same with OAL's gradually but providing you dont get excessive pressure signs, HOW FAR CAN YOU GO WITH COMPRESSED POWDER CHARGES????? Are these guys really crunching it down when they load up????? I just cant see how they are loading 46gr varget in a lapua case with the very long 155 scenar and still getting 2.800 OAL without really crushing the powder?

 

[LESLEY]

do not forget to try RL 15 i shoot it in my 308 with 155s and do very well at 1000 yds. i am running them around 3100fps

 

[memilanuk]

Some of the 'bigger' charges may be using Winchester brass... there's about a 15gr weight difference between Winchester and Lapua brass; works out to about a grain or so difference in actual charge weights.

Also, most of the really 'full' loads that I've seen,or used) were for the much stubbier 155gr SMK/Nosler bullets. The 155gr Scenar is about the same length as a 175gr SMK, so seating to mag length and sticking that much powder in there,especially in Lapua brass) could be a trick.

Just for kicks... look at what Nosler's loading manual recommends for Varget behind a 155gr bullet,hint: it's enough to make most Palma loads look wussy). I'm not recommending it by any means, but figured I'd throw it out there just for comparison.

Monte

 

[fox]

These guys are specifically quoting the 155 Scenar and Lapua Brass though at 2.800"?

 

[memilanuk]

Then, yes, they are most likely compressing the ever-lovin' snot out of those loads.

 

[Will]

Either compressing OR they are using a long drop tube to allow the powder to settle more uniformly. It's the only way I can comfortably load 46 gr 4895 in my cases without hearing "CRUNCH" !!
Am using a regular RCBS powder funnel w/ length of arrow shaft glued up,,fits slightly over neck of case) mine is over 8" in drop.
Works for me.

 

[SF340Driver]

I run 44.5 grains of RL-15 with Lapua brass loaded to 2.840 -- slightly compressed.

 

[Link]

Hi guys

I have a 308 100 XR My most accurate load to date is 34 gr imr3031.[way below min] 168 SMKs at 2.955 [a lot of jam]
I have shot about 12 groups of 5 with a .600 average. at 100 yrds.

I am wondering if there is a better load?? I keep trying other things but keep coming back to that load.

thanks Link

 

[Rustystud]

Fox:

If you are not confined to the 150 grain bullets. Here is what a few of us are doing here in North Carolina. We are shooting Berger 210s in 30 to 32 inch 1:10 barrels. We are pushing them with VV 550. Best accuracy has been in the 2600- 2650 fps. The velocity at 1000 is about 1415 fps. They are holding .5 moa vertical and what ever the wind will allow. They are just a few inches difference in wind deflection from the hotter calibers. The arc of flight is much greater but it is a known distance. I am shooting about +36 moa at 1000.

Rustystud

 

[DRGreysun]

FWIW,

30 in. 1:12, RPA action, 155 gn. Sie. Palma,,naked) Lapua Brass, FL resized, Russ. Pri., 47.5 Varget. COL: unknown, jump: unkown, Velo. unknown. It dose get the job done for one shooter I know. Compressed, oh yeah!

 

[Asa_Yam]

,naked) Lapua Brass...47.5 Varget... Compressed, oh yeah!

And if you used Winchester brass, you wouldn't be compressing the charge.

There are down sides to compressed loads:

- It's hard on seaters. Seating large numbers of bullets over compressed charges will flare or crack the stems on Redding seater dies. While Forester uses stronger material, the die still isn't designed to work against the additional resistance.

- The powder pushes back. It is not unheard of for bullets to be pushed forward by the powder "springing back". Light neck tension or bullets seated long increase the odds of this happening.

 

[JERRYHM]

Sierra 155 and Lapua 155 bullet test.

The S155 bullet is 1.135” long and the Lapua is 1.280” about 0.145” longer.

Test rifle: 308 palma rifle – Quadlite action, Krieger 1:13 barrel with the Bisley chamber,
2393 rounds thru the barrel at start of test. The high palma score with this barrel is 448-22X..
NF 8-32X scope, rifle will be used in “F” class mode.

The S155’s touch the lands at 2.849” and the L155 touch at 2.860”. Do the the height of the
Powder column Winchester cases were used. CCI-BR primers. Powder is Varget lot # 1029034133.
I could not seat the L155 with out vibrating the the powder charge, the powder column height was reduced by 0.120” which allowed the L155 to be seated to jump 0.015”.
The powder charge for the L155’s was vibrated to reduce the powder column so the bullet seating would not compress the powder. Without vibrating the bullets and the seating die can be damaged and the OAL was not be repeatable.
A 50 round loading tray was bolted on top of a vibrating case tumbler and the cases were vibrated from 2 to 5 minutes. A 0.292” diameter pin the same length of the L155 bullet was made to check the powder height, so the powder was below the bullet’s ,OAL) seating depth..

Test one: Chronograph test at 100 yards to find loads so both bullets would have the same MV.
Five shot groups, both jumping 0.015”

S155 – 46.0gr – MV 2941 - ES 21 - SD 08 - Group = 0.398” OAL = 2.835”
S155 – 46.5gr – MV 2979 – ES 14 – SD 05 – Group = 0.544”
S155 – 47.0gr – MV 3015 – ES 12 – SD 05 – Group = 0.254”

L155 – 45.6gr – MV 2977 – ES 07 – SD 07 – Group = 0.395” OAL = 2.845”
L155 – 45.9gr – MV 2990 – ES 40* – SD 14 – Group = 0.343” *Chronograph problem.
L155 – 46.2gr – MV 3013 – ES 07 – SD 03 – Group = 0.388”
L155 – 46.5gr – MV 3032 – ES 13 – SD 05 – Group = 0.349”

Loads selected for group testing at 300, 600 and 1000 yards:

S155 47.0 gr MV 3015

Name: Palma S155 Altitude: 500 feet


G1 BC: 0.450 Temperature: 75 øF


Muzzle Vel: 3015 f/s Pressure: 29.53 in Hg


Sight Adj: 3.345 MOA Humidity: 25 %
Zeroed Rng: 100 yards Wind Speed: 10 mph
Bullet Wgt: 155 grains Wind Dir: 03:00 O'clk
Sight Height: 1.5 in Range Slope: 0 deg

Report Trace

Range Velocity Drop Drift Zero Adj
Yards f/s inches inches MOA
0 3015 0.00 0.00 ----
100 2812 -2.00 0.62 0.0
200 2617 -8.41 2.57 1.4
300 2431 -19.90 5.99 3.5
400 2252 -37.28 11.05 5.9
500 2081 -61.53 17.92 8.7
600 1918 -93.82 26.84 11.8
700 1763 -135.59 38.04 15.4
800 1618 -188.56 51.79 19.3
900 1485 -254.83 68.36 23.9
1000 1364 -336.91 87.98 29.0


L155 46.2gr MV 3013

Name: Palma L155 Altitude: 500 feet


G1 BC: 0.508 Temperature: 75 øF


Muzzle Vel: 3013 f/s Pressure: 29.53 in Hg
Sight Adj: 3.337 MOA Humidity: 25 %
Zeroed Rng: 100 yards Wind Speed: 10 mph
Bullet Wgt: 155 grains Wind Dir: 03:00 O'clk
Sight Height: 1.5 in Range Slope: 0 deg

Report Trace

Range Velocity Drop Drift Adj
Yards f/s inches inches MOA
0 3013 0.00 0.00 ----
100 2833 -1.99 0.55 0.0
200 2659 -8.33 2.27 1.4
300 2492 -19.58 5.25 3.4
400 2331 -36.44 9.63 5.7
500 2176 -59.70 15.55 8.4
600 2027 -90.32 23.16 11.3
700 1885 -129.40 32.65 14.5
800 1749 -178.29 44.22 18.1
900 1621 -238.57 58.06 22.1
1000 1502 -312.10 74.39 26.6
Group testing today had two suprises:

1. The L155’s shot after the S155’s had elevation problems, needed five rounds to settle down the elevation. The S155’s shot after the L155’s didn’t have the elevation problems. Should have cleaned the barrel between bullet changes. The two bullets do not like to share the same barrel.
2. Both loads shot good at 300 and 1000 yards, but shot poorly at 600 yards with elevations over 4 inches.

The groups at 300 yards:

S155 five shots = 1.218” mostly horz.
L155 five shots = 0.667” mostly vert.

The groups at 600 yards:

S155 ten shots = vert. = 4.052”
L155 ten shots = vert. = 4.882”

The groups at 1000 yards:

S155 elevation was about 7 inches.
L155 elevation was about 5 inches.
The wind range used for both bullets was about,3 min) the same.

MOA come ups on NF scope:

S155 100-300 = 3.50, 300-600 = 7.00, 600-1000 = 18.75, total = 29.25
L155 100-300 = 3.00, 300-600 = 7.00, 600-1000 = 18.25, total = 28.25

The Sierra bullet matched the ballistic report, where as the Lapua bullet did not match the ballistic report.

Would that mean the Sierra’s BC is more accurate than the Lapua BC???

Both bullets traveling at the same MV are very closely matched and I think it would be hard to prove one over the other.

Testing at 600 yards on Nov 02,2004

Results of two five shots groups each with S155’s and L155’s.

Both bullets shot with the same elevation,exactly the same elevation).

Group one with S155 was X=1.288” Y=2.201”
Group two with S155 was X=2.564” Y=2.609”
Group one with L155 was X=2.925” Y=1.602”
Group two with L155 was X=1.968” Y=0.644”

Results: When I cleaned the barrel between bullets tests the elevations of both bullets were the same……
I do have to say any bullet that can shoot less than 1 inch of elevation at 600 yards would be hard to beat!!!!!!!! Even though I have over 8000 Sierra’s 155’s and only 400 Lapua 155’s. . . . . . . .


Picture of 300 yard Lapua group on next page.

Jerry Tierney

 

[Spotcheck_Billy]

Great report Jerry!

In my limited experience with Lapua Scenar bullets of several diameters and weights it's become obvious to me that they do better jammed,about .015" on the average) into the lands than they do jumped.

Has your experience been different?

I'm just curious as to why you jumped yours.

 

[fox]

Great post Jerry but just HOW long is that Palma barrel to get those MV's????? 30"+?

I am getting good accuracy with most bullets so far but havent managed to push anything over 2800 with any regularity, Im almost starting to wonder if my chrono is dodgy??? Still Im having fun testing everything but you guys across the pond would cry if you new how much we pay for bullets and powder.

1lb of Varget= $64
100 Sierra 155's= $34
100 Lapua 155's, wait for it...............$50

I should go back to archery, at least you get a couple of goes with the arrows

Thanks for the info guys, its all good fun.