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!!
I also have weighted the brass and weighted the bullets.

 

[ChrisGarrett]

Re: 338 lapua velocity spread

25 fps is pretty good for reloaded ammo. We're not perfect and things aren't identical or exact. Maybe try a powder that has a lower density and fills up the case more?

Chris

 

[Supersubes]

Re: 338 lapua velocity spread

Is that an extreme spread? If so what is the standard deviation?

 

[Rookie]

Re: 338 lapua velocity spread

Why?

I assume you realize that 25fps spread is less than 1% of 2700fps. Some or all of the difference could probably be attributed to chrony error.

I wouldn't sweat it, especially with those groups!!!!

 

[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.

 

[Clark]

Re: 338 lapua velocity spread

2900 fps with 300 gr is hard to believe.

At that velocity, with those bullets, the difference between .1" and .5" groups at 100 yards is 10mph wind.