Range Report 338 lapua velocity spread???

[stenger]

i have a 338 LM on a bat action 30 inch bartlein 1/10 barrel. i currently shoot 300 gr. lapua bullets at 2700fps i am getting about a 25 fps spread. gun groups awesome at 100 and i have killed wood chucks at 700 yards with it. i want to get the spred down lower. i am running 82 grains of n560 sitting on the lands 215m primers,lapua bullets. getting .1 and .2 groups at 100 with this load. i am also running .002 neck tension. what would be your recommendation to get the spred lower? i have tried working with the N560 no luck. i think i am going to a slower powder. what would you all expect out of that gun for velocity spread?? i currenly have the following powders
1. retumbo
2. h1000
3. RE 25
4. US 869
5. N 170
6. H5010
Thanks!!

 

[steve123]

Re: 338 lapua velocity spread???

More neck tension.
different primers
neck turning
inside neck reaming
flash hole deburing
weight sorting cases

25fps spread isn't too bad.

Steve

 

[VTi]

Re: 338 lapua velocity spread???

I haven't shot the 300gr Lapua pills yet, so I'm not sure how the bearing surface compares to the 300SMK, but 2700fps seems awfully slow for a 30" tube. Are you doing this intentionally, or did you try to push the upper limits a bit?

The load I'm currently running:

Lapua Brass
300gr SMK
95.0gr Retumbo
CCI 250
COAL 3.620" (AI Mags)
.003 Neck Tension

Cases sorted to +/- 2.5gr. Not super tight tolerance, but does weed out a few of the very high and low case volumes.

Velocities out of my current rigs:

Surgeon XL 29.5" Rock 1:9.4 = 2905fps
Surgeon XL 25.0" + Suppressor, Krieger 1:10 = 2835fps

I don't think your spread looks too bad, if it's ES, not SD. Mine is usually around 15-18fps ES, depending on the day. Retumbo seems very consistent, and is all I shoot in my .338LM's now, short or long barrels.

I'd definitely give Retumbo a try in that 30" tube, especially if you're looking to get the full velocity potential out of your rifle. It's not 100% necessary, but you'll appreciate it if you shoot past 1500yds. Small groups at 100dys won't mean much at that distance, but the extra velocity will produce many more hits at 1000yds+ in the wind.

This might not be the exact info you're looking for, but just a few random thoughts. Let us know if you need any more info about shooting/loading .338LM.

 

[psinclair]

Re: 338 lapua velocity spread???

I agree with VTi, Retumbo is the best powder I've worked with in 2 different .338 LMs with the 300gr bullets, Both the SMK and the Scenar. It produced the lowest ES and the highest velocity, plus outstanding accuracy.

For the 250s the winning choice was VV N560...for accuracy, ES and velocity it was the clear winner in both rifles.

Both rifles were GAP builds, Bartlein bbls. One is 26" 1-10" the other is 28" 1-9.75"(Surgeon action) The 26" is a GAP 7000 action.

I do my testing at 500 meters, on days without mirage.

 

[stenger]

Re: 338 lapua velocity spread???

Thanks for the help i just think that 560 is to fast for those heavy bullets. starting this wed. i am headed to the range for testing i am going to test retumbo first seems that a lot of peolple are having good luck with it. i have weight sorted my brass, and primer pocket reamed flash hole as well. also weight sorted the bullets and also sorted the from base to ojive lenghts. got to be the powder. ill let you all know how it went.

i have been hearing that US 869 is producing very well to!!

 

[VTi]

Re: 338 lapua velocity spread???

Be sure to check back in with the results.

 

[stenger]

Re: 338 lapua velocity spread???

Well after four days of testing these are my results. i first tried retumbo with great velocity spread in the single digits, but the accuracy stinks, i was getting almost 2900 but was averaging .5 groups at one hundred. i then tried rl-15 which sucked. i then tried us 869 with great velocity spread but once again the accuracy was terrible. i then went back to my old load of 82 grains of n560 and shot it at 615 yards. i hit four prairie dog size steel plate in a row. i was happy! i also shot it at 425 yards and got a 1.9inch group. but once again i wanted to play with it some more. i started playing around with sierra 300gr. bullets. i gave sierra a call and they recommended IMR 4350 at 78 grains for accuracy. well i gave that a try and had awesome results. i was getting high. 1's and .2's, groups five groups in a row to be exact, with a ES of 11fps now i am really happy, but have not had a chance to test it at 600 yet. i could not get any of the other powders to shoot. i am also jammed .030 in the lands.
now i have noticed another problem with both of the loads that i have found to be accurate. it will shoot great groups for a while and then out of no where, they will start to open up for no reason. i tried playing with the seating depth, thinking i might be getting throat errosion but that did not help. the only thing i can think of is that the barrel is getting dirty, or the brass is getting old and needs anealed or tossed out. i would have done these tests but had to go back to work. i usually clean my rifles every 20 rounds, but do to always being in a hurry because i work out of town i was was shooting approx. 50 rounds before cleaning. What do you all think.