Load development question - seeking advice

[mjgillen]

Hello all! New barrel so doing load development. All the brass is once fired / fire-formed.

Looking at the attached photo, I am trying to determine the best load charge to pursue. All loads are 15 thousandths off the lands as best I could load. Each load is as precise as I could make them using my scale and trickler.

5 shot groups @ 100 yards.

So, what do y'all think?

Here is the chronograph data:

22.0gr ES = 37.22 SD = 14.74
22.5gr ES = 39.60 SD = 14.74
23.0gr ES = 25.41 SD = 12.71
23.5gr ES = 18.16 SD = 8.04
24.0gr ES = 17.77 SD = 7.69
24.5gr ES = 25.90 SD = 11.45
25.0gr ES = 18.19 SD = 7.73

Thanks,
Michael

 

[Sniper338]

24.5 to 25, or alittle higher till you see pressure signs...

 

[Rsadams]

What causes the stringing like on 22.5?

 

[Bart B.]

Those groups are statically the same size.

Shoot at least 15 shots per load; 20 is better.

 

[spclark]

Help if we knew what distance those groups were fired at, as well as what cartridge, bullet, propellant... otherwise I'd say stick with 24.5 & mess with seating -/+ a little!

That load's got impressive lack of vertical, that's my primary criteria to judge by.

 

[mjgillen]

5 shot groups @ 100 yards
.223 Rem, Berger 80.5gr full bore bullets, Varget powder, Lapua brass, CCI 450 primers.

Shot this morning in Dulzura, CA
Temp about 70 degrees
Mild humidity
Calm wind

 

[Bart B.]

What causes the stringing like on 22.5?

Variables in how the rifle is held, for the most part. Typically different places the butt plate is vertically against the shoulder. Body torque vertically ain't the same for each shot.

Sometimes by bedding pads between barrel and fore end transferring external forces up to the fore end and onto the barrel while bullets go through it. Bullet departure angle spread of 1/2 MOA will do that.

 

[Richard Coody]

What causes the stringing like on 22.5?

http://www.6mmbr.com/verticaltips.html

Some have vertical stringing and some have horizontal. Could be a problem with hold and rifle.setup. Could be just part of load development. That search for the right load and seating depth. Hard to say not being there.

 

[T-shooter]

I would work from 25.0 up in 2/10 increments (maybe try 24.8 too). Check for any signs of overpressure as you increase the load. The 25.0 load may be right on with just one slightly above the other 4. Once you think you have it, shoot 15-20 like Bart said. If you know you pulled a shot, disregard it and reshoot. What kind of scale are you using and how close are the powder charges?

 

[Bart B.]

I think it's a waste of resources to work up loads for most commercial rifle barrels in less than one grain steps. A barrel maker said the powder charge increments should equal group sizes in MOA shot. If groups are around 1/4 MOA, increment charge weights in 1/4 grain increments.

The rules of probability always apply. Smallest few-shot groups happen as often as largest few-shot groups. Once for each. All the others are between those extremes, most clustered around the middle or average size.

 

[Jet]

Michael

What are your accuracy requirements for this rifle? Will this be an FTR rifle. Based on your target I would select 24.8 gr, adjust seating depth and neck tension to fine tune it and go shoot.

Good Shooting

Rich

 

[Mulligan]

I think it's a waste of resources to work up loads for most commercial rifle barrels in less than one grain steps. A barrel maker said the powder charge increments should equal group sizes in MOA shot. If groups are around 1/4 MOA, increment charge weights in 1/4 grain increments.

The rules of probability always apply. Smallest few-shot groups happen as often as largest few-shot groups. Once for each. All the others are between those extremes, most clustered around the middle or average size.

Are you suggesting load development be done with powder in 1 full grain steps?
CW

 

[Bart B.]

Are you suggesting load development be done with powder in 1 full grain steps?

Yes, if groups are about MOA.

 

[Mulligan]

Yes, if groups are about MOA.

Help me understand you logic, how would case volume factor in?
Is there a correction factor for larger/smaller volumes?
CW

 

[Bart B.]

Help me understand you logic, how would case volume factor in?
Is there a correction factor for larger/smaller volume

I've never used case volume for anything.

There is a decent correction factor for case weight. For each 10 grains change in case weight, change charge weight 7/10ths grain in the opposite direction; less powder for heavier cases. A good rule of thumb.

Regarding my logic.....

Few-shot groups have a 3X to 6X range in size; sometimes more. Check the many few-shot groups shot by each person in this benchrest match:

http://azbrs.com/matches/2016-lv-hv-cactus-classic/

They ain't all the same size and the smallest ones shot are seldom the first one of several in a many group aggregate.

Many times, when someone shoots several all about the same size, their marksmanship opens up small groups the rifle and ammo would otherwise produce shot free recoil.

 

[mjgillen]

What kind of scale are you using and how close are the powder charges?

Its a Scott Parker tuned Ohaus M5 and I weighed them to the kernel using a Dandy trickler.

I think it's a waste of resources to work up loads for most commercial rifle barrels

Its not a factory barrel, its a Shilen "pre-fit" .223 Match barrel for my Savage 12FV that I got from Northland Shooters Supply

What are your accuracy requirements for this rifle? Will this be an FTR rifle

Yes, FTR out to 300 yards as well as a 600 yard silhouette shoot.

Thanks to everyone who chimed in. I'm going to take your suggestions and hopefully post back once I have it dialed in. That could take a while as my nearest range is an hour drive.

Best wishes,
Michael

 

[CharlieNC]

What approach are you using? If ladder or ocw, then it looks like a node in the 24.5 to 25.0 region. Since you're interested in 300Ftr, at 24.7 load up 5ea at different seating depths and shoot at 300yd to evaluate performance. If not satisfied load in .2 increments in the node region to fine tune, and move out further than 100yd to obtain a more pronounced and representative answer.

 

[T-shooter]

Here is a good read. Dan Newberry's OCW instructions: http://optimalchargeweight.embarqspace.com/#

If I remember correctly, he suggest working the powder load to get the best group and then work the seating depth to tighten it up.

 

[JBO]

Here is a good read. Dan Newberry's OCW instructions: http://optimalchargeweight.embarqspace.com/#

If I remember correctly, he suggest working the powder load to get the best group and then work the seating depth to tighten it up.

+1

 

[Bart B.]

I think Optimum Charge Weights and Barrel Times for best accuracy are another pair of myths.

Having seen several barrels of the same make, length and profile shoot the same lot of ammo well into sub MOA at 300 to 600 yards and average muzzle velocity across them is 50 fps or more, that counters all their theories. Some of those barrel's bore and groove diameters belled out .001" or more the last half inch of their length; no copper wash there. Bullet jump distance to rifling across all barrels had a spread of .040" or more; less for barrels with only a couple hundred rounds through them, more if a couple thousand.