Case prep for 100 yards

B

Bill Daniel

New member
I enjoy handcrafting my reloads in the never ending search for my rifles perfect cartridge. If my health holds I would like to stretch my distance to 1000 yards but all my Load development takes place at 100 or 200 yards. For practicality how much dose case prep affect accuracy at that distance?
My full case prep includes selecting cases by measuring variations in case neck thickness to <or= to 0.002” then turning the neck to a uniform thickness, deburring the primer hole and uniforming the primer pocket as well as the routine clean, size, trim and chamfer.
So how about it, for 100 to 200 yards how much does the extra selection, neck turning, primer hole deburring and primer pocket uniforming affect accuracy?
All the best,
Bill
 
Hi Bill,

My take on this: I shot in 1,000 yard F Class for 6 years and did a lot of load development work at that time. I took some once-fired LC Match brass and did all the case prep that you just described, including sorting the brass by weight. I shot it side-by-side with some new out of the box Lapua brass and the Lapua out shot the completely case prepped brass by a significant amount. Summary: save yourself a lot of time and work and buy Lapua brass. Almost to a man, everybody on the line in F Class shot Lapua. Hope that helps.

Don
 
Nothing wrong with good quality new cases. In 308 Win and 30 caliber magnums, I've seen insignificant difference in accuracy comparing new to reloaded fired ones. New cases are already full length sized to start with.

Some may need their necks uniformed. If you can prove uniformed flash holes improve accuracy, do so.
 
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Military teams learned years ago that reloaded Lake City arsenal fired cases from semiautomatic 30 caliber match rifles never shot as accurate as new cases. The rifle bolts never had their faces squared up; fired case heads were out of square. When reloaded then fired again, shots strung from 7 to 1 o'clock well over a MOA at right angles to the bolt lug axis.

In and others have shot new LC match cases rebulleted with Sierra HPMK's as accurate as new commercial cases.
 
Bill,

I'll add to the others that some of this will depend upon the gun and the load. In the M1A, I found a significant improvement from deburring flash holes when I used 2520 spherical propellant, but saw no apparent difference with three different stick powders, all of which shot just as well as 2520 did with deburred flash holes. The good news is that while the prep only may help, there is none of it that hurts, so I select and set aside and fully prep the best 20% of the cases in a lot for taking to matches. It's a precaution against a problem that may never show up, but it eliminates one possible variable. I have the tools to prep cases so why not use them? For practice keeping my trigger finger working, though, I don't bother.

What Bart B. pointed to in gas guns should be addressed. I got lucky with my M1A in that it ejects cases with square heads. So I won the bolt and receiver lottery by getting a very square pair and have had no issues with accuracy from resized cases. Nonetheless, whatever gun you are using it in, it is worth your time to square up the receiver and bolt face and lugs before setting your final headspace to minimum length. That combination will make all your brass shoot well and last longer.
 
If it helps I do the following and on a good day can shoot 1/4 MOA

Used brass

Shoulder based trim (Gerard or the Tri Trimmer so chamfer and deburr and trim all in one) but not anal (varies at least .003). I trim short to mesh with my annealing

Set back minimum for the chamber (3 target rifles, I am less picky oh the hunting rifles and go for generous chamber setup - I don;t hung but load for a brother who does)

I don't do anything to the primer holes.

RP shoots as good as Lapua

I keep same brass but don't sort.

Loads are good to 1/10 either way.
 
I agree with USSR, buy good brass. Lapua, Alpha, Peterson, Norma are all exceptional straight from the box. I don't mess with flash holes and never bother turning a neck since my rifles are chambered for standard necks. Find the right combo of seating depth, powder, charge weight and primer and you will have ammo capable of shooting quarter MOA
 
For decades, Sierra never prepped cases used to test their bullets for accuracy. Good match bullets shot 10 round groups under 2/10 inch at 100 yards; one after another after another........
 
Bill Daniel said:
I enjoy handcrafting my reloads in the never ending search for my rifles perfect cartridge. If my health holds I would like to stretch my distance to 1000 yards but all my Load development takes place at 100 or 200 yards. For practicality how much dose case prep affect accuracy at that distance?
My full case prep includes selecting cases by measuring variations in case neck thickness to <or= to 0.002” then turning the neck to a uniform thickness, deburring the primer hole and uniforming the primer pocket as well as the routine clean, size, trim and chamfer.
So how about it, for 100 to 200 yards how much does the extra selection, neck turning, primer hole deburring and primer pocket uniforming affect accuracy?
All the best,
Bill
Click to expand...

What rifles are you referencing here?
Factory or custom? Bit of both?
 
The benchrest match records pretty much shows the most accurate stuff put all shots for competition inside about:

3/10ths MOA at 100 yards.

4/10ths MOA at 200 yards.

5/10ths MOA at 300 yards.
 
Thanks to all. My bolt rifle is a factory Savage FCP 308 with an added cheek riser. Best group with 175 gr. SMK was 14 of 15 shots into 0.6 moa with the last shot a shooter induced flier. This current project is a newly assembled LR308 in 6.5 Creedmoor. Working up loads currently. I like Lapua in my 308 but want to try some ADG in the Creedmoor when it comes off back order.
All the best,
Bill
 
Bill Daniel said:
Thanks to all. My bolt rifle is a factory Savage FCP 308 with an added cheek riser. Best group with 175 gr. SMK was 14 of 15 shots into 0.6 moa with the last shot a shooter induced flier. This current project is a newly assembled LR308 in 6.5 Creedmoor. Working up loads currently. I like Lapua in my 308 but want to try some ADG in the Creedmoor when it comes off back order.
All the best,
Bill
Click to expand...

Good shooting.
No need to neck turn if using good brass and and your chamber was made to work with that brass.
Using a Wilson type in-line seater will take about 1 thou more of your bullet runout away compared to screw BR type seating dies.

What kind of shooting/competing are you wanting to do?
Short range? Distance? If so, how far?
 
My tests on bullet runout cause and correction proved that the straighter case necks are relative to case shoulder-body axis and least amount of bullet interference fit to case neck, any seating die ends up producing straight cartridges. All seater dies for a given cartridge don't have the same diameter bullet guide. My Wilson seating die has the largest one.

As no commercial cartridge runout gauge holds a cartridge relative to the dial indicator like a cartridge aligns its bullet to bore center when fired, any measurement is misleading. All gauges and their different use setup won't show the same runout on a given crooked cartridge.

A perfectly straight rimless bottleneck cartridge correctly sized for the chamber can have its pressure ring .001" or more off chamber center when fired. At that time, the bullet tip will be about half that much off the bore center in the opposite direction. The cartridge axis pivots about its shoulder contact point to and centered on the chamber shoulder. It's very repeatable across all such cartridges.

Cartridges headspacing on their shoulder don't rest on the chamber bottom when their primer fires.
 
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Case prep for 1000 yards is exactly the same as case prep for 100 yards.
Benchrest is a totally different game from 1,000 yard F Class. The Benchrest guys do things the rest of us would never consider. Read this(Especially the paragraph headed 'Different Organizations, Different Rules'.). There's a link to F Class at the bottom.
https://www.6mmbr.com/1000ydpg01.html
 
I've never shot competition other than 22LR. And something I can't understand is why a rifle that shoot's 1/2 MOA groups at 100yds won't still shoot 1/2 MOA at 1000 yds. The idea that at some point the bullet goes to sleep and suddenly get's more accurate is lost on me! You get beyond a certain range and I believe it's all about shooting skill!
 
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