Velocity SD or Group Size suggestions for new load

[Kirker912]

I've been reloading for years but never to the accuracy that I am looking for now. I've greatly improved my loading process but I am still getting large variances in Velocity even when my groups look good.

What SD or ES should I be trying to achieve? Should the load with the best SD always be the best shooting load?

New Remington Brass, Chamfered, primer pocket uniformed, flash hole deburred
CCI Bench Rest Primers
RL-15 Powder trickled onto scale by lyman system
Lapua Scenar 155 BTHP

Loaded on RCBS Rockchucker with Redding Comp Seater die
COAL 2.811 (Currently holding variance down to 0.001)

Where do you suggest I go next with my load? Do you suspect any problems in my process?
Data is below


Charge 44.8
Velocity
2895
2886
2898
2886
2900
AVG 2893
SD 6.633249581


Charge 45
Velocity
2915
2904
2910
2924
2904
AVG 2911.4
SD 8.414273587


Charge 45.2
Velocity
2884
2891
2907
2913
............3052 but thrown out due to chronograph problem
AVG 2898.75
SD 13.52466882


Charge 45.4
Velocity
2932
2924
2925
2916
2898
AVG 2919
SD 13.03840481


Charge 45.6
Velocity
2952
2960
2969
2980
2981
AVG 2968.4
SD 12.58

I apologizes for some of the rotated pictures, photo bucket won't corporate.

 

[Daniel Rando]

Re: Velocity SD or Group Size suggestions for new load

Did you clean your barrel between charges?

 

[bohem]

Re: Velocity SD or Group Size suggestions for new load

Read through this thread and decide what you'd like to do with the rifle and load combo.

 

[Kirker912]

Re: Velocity SD or Group Size suggestions for new load

I did not clean the barrel between charges.

Thanks for the read bohem. That puts things into perspective concerning SD. It's possible I'm focused too much on the SD and now need to choose the load by the shot group.

The question is which load do i choose to continue testing? 45.4 has a very nice group, although 45 has little vertical dispersion and some of the horizontal could be wind or the shooter(me).

 

[bohem]

Re: Velocity SD or Group Size suggestions for new load

I would play with the seating depth on the 45.0 load a little bit and then test the 45.0-45.4gr range again with a more extensive test.

Then pick the load based upon your groups at distance and the %V not just the SD and ES of the load.

 

[bigwheeler]

Re: Velocity SD or Group Size suggestions for new load

Your velocities are not varying much at all. Load up 10 a 45.3 and go shoot two
groups of five to see if it repeats. You want a load that is a bit forgiving. I would
rather have a load that shoots 1/2" with 50 foot per second spread than one
shooting 1/4" with a 10 foot per second spread.

 

[diriel]

Re: Velocity SD or Group Size suggestions for new load

you might want to use 91% alcohol and measure the capacity of those remington cases. Weight sorting is not quite enough. Also, do you bump the shoulders back 1-2 thousandths?

Seriously, measuring internal case capacity is a good idea. Another good idea would be to lightly turn the necks of your brass. I have a forster case trimmer with an outside neck turning attachment personally. Some folks prefer to inside neck ream, as it can take out "the doughnut". Getting a really good es/sd depends on going that extra mile, without it, you may as well consider an ES of 20 or less "Good". You can decide for yourself what ES is best for your usage by calculating bullet impact at max distance you will shoot from max velocity Vs. min velocity. That will give you a rough idea as to what to expect in vert stringing.

Have a good one,
Gary

 

[MitchAlsup]

Re: Velocity SD or Group Size suggestions for new load

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kirker912</div><div class="ubbcode-body">What SD or ES should I be trying to achieve?
SD 6.633249581
SD 8.414273587
SD 13.52466882
SD 13.03840481
SD 12.58
</div></div>

With SDs like those, there is nothing you can do. Really, less then 25 is considered good. Less than 20 is great. Less than 15 is superb. And I've never seen any consistent batch come out less than 13.

 

[Kirker912]

Re: Velocity SD or Group Size suggestions for new

It sounds like my numbers are not as bad as I figured. I will however keep working to improve them. I probably won't ever be done. So you will probably see a lot more of me on here.

I believe Santa "aka wife" is bringing me a neck turning tool for Christmas so I've got a few weeks to wait on that. I am contemplating turning them on my lathe. I would need to make a collet first.

In the mean time I will start working up the new loads and test. I am having a hard time deciding when to test powder charge and when to test different COAL. Should I decide on a charge weight before moving to COAL.

I will report on the alcohol measurement soon. I do not have a burette but I assume I can do it with a syringe. Agree?

 

[bigwheeler]

Re: Velocity SD or Group Size suggestions for new

I go with the bullet man. recommendations on coal while working up a load. Then
I play with seating depth if I'm trying to get the last bit of accuracy out of the load.
You will find you have to chase the throat as the barrel wears to keep the same
jump.

 

[ChrisGarrett]

Re: Velocity SD or Group Size suggestions for new load

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kirker912</div><div class="ubbcode-body">What SD or ES should I be trying to achieve?
SD 6.633249581
SD 8.414273587
SD 13.52466882
SD 13.03840481
SD 12.58
</div></div>

With SDs like those, there is nothing you can do. Really, less then 25 is considered good. Less than 20 is great. Less than 15 is superb. And I've never seen any consistent batch come out less than 13. </div></div>

Yeah, sounds like the guy who complains about a 5 shot .250" groups at 300 yards.

Now, repeating those numbers, group after group, is an entirely different matter.

Even a blind squirrel finds a nut from time to time.

Chris

 

[Kirker912]

Re: Velocity SD or Group Size suggestions for new load

I measured 5 once fired cases last night and now realize there is probably a better way to do it. Each case appeared to hold 3.72cc of 91% alcohol with a convex meniscus.

I noticed others are measuring volume by weight, which sounds easier, and probably more accurate. I'll have to try that tonight and compare the difference. Does anyone have tips or comments on this method?

Thanks for the recommendation on coal. I will stick with 2.811 until I have my power charge decided on.

 

[MitchAlsup]

Re: Velocity SD or Group Size suggestions for new

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kirker912</div><div class="ubbcode-body">Should I decide on a charge weight before moving to COAL.</div></div>

Yes, this is the general method.

 

[Kirker912]

Re: Velocity SD or Group Size suggestions for new

I found a good use for those odd left over rounds that you end up with during load development. Mine brought home two deer tonight. Minute of deer is pretty forgiving.

 

[427Cobra]

Re: Velocity SD or Group Size suggestions for new

I load for smallest ES SD, then I adjust my Tubb T2K brake in/out to shrink the groups

 

[diriel]

Re: Velocity SD or Group Size suggestions for new

I generally start around 15 thou off the lands for general powder work up. After I find the load that seems to be the best, I then begin to tweak the seating depth in 5 thou increments from about 25 off the lands, to as much as 5 into the lands.

Do a look up on OCW. Some good info to be had. I admit I used the good old ladder method for years with good results, but for me it takes longer and burns more components.

Either way, have fun!
Gary
P.S. The best shooting rifle I ever had required Exactly 18 thou off the lands, 1 thou either way and groups opened way up, and the rifle was only 3/4 moa-ish. But at that one very precise load-out .2-.3 "easy". Thing about that was, I had to go through a bunch of pain with pointing bullets, and sorting them not only by weight, but by ogive ect....can we say Pain In My ASS!?

That rifle taught me to HATE...and love...but mostly to hate! haha I am glad that barrel is finally toast, and it's time for a new tube.

 

[Kirker912]

Re: Velocity SD or Group Size suggestions for new

Cobra, do you make adjustments in 1/2 turn increments? I just always assumed the brake should be oriented with vents to the side and screwed all the way on. Although if I want to start messing with a brake I'm going to have to pull my barrel and thread it first.


25 off the lands is further than I ever imagined. It goes to show that I've got a long ways to go on this project.

Bullet comparator is in the mail already. That should give me something else to do when the weather is bad out.