1000 yd Accuracy

[BCBRAD]

Thanks for input thus far. With my 260 Rem and a 123gr Scenar my ES is 64 and SD 28.19 this is with 43.8 gr of H-4350 speed is 3050fps on average 26" bbl. In 12 shots fired I have two that record lower velocities, SD would be 15.15 if they were excluded.

What steps can I take to lower these numbers?

 

[rnbra-shooter]

BCBRAD:

The single most common recommendation to get improved velocity consistency is, "make your load hotter". But in your case, your load is under Hodgon's max for 120 grain bullets (they indicate max 46.5gr H4350, vel=2960, press=58,200psi) but your speed of 3030fps indicates a max or a near max loading. Hmmm, odd. Do you have any idea if you are at or near max?

Before you change things, make sure you are starting from a reasonably baseline:
- same kind/lot of brass?
- consistent neck tension?
- how many shots in your groups where your chrono'd your load?
- do you know that your chrono is correctly? (not picking up muzzle blast; giving sensible readings from a .22 match rifle, or air pistol; do you have a known-good rifle/ammo combo you can use to confirm your chrono setup?)


When you know that your measurements are real, here's what you can try:
- a hotter load (if this is feasible)
- a different batch/brand of primers
- a hotter primer
- a milder primer
- if you are seating into the lands, try some bullet jump (say .010")
- if you were jumping, try seating .005" into the lands instead
- a different bullet (try a Sierra 142MK)
- if you were using heavy neck tension, try lighter neck tension (and vice versa)
- if you are using moly, be sure to fire several shots after cleaning and before chrono'ing
- If you are using moly, you can try using unmolied bullets (if you aren't using moly, it's probably not worth trying moly as a solution to this)

 

[BCBRAD]

I have tried hotter loads, cratered primers (small amount) @ 45gr so coming back down
Using Federal 210 match primers
I am 0.002" off the lands
Lapua brass
My .22RF Silhouette rifle is right in line what it should be over the Chrono
Its a Savage Model 12 LRP with a 26" bbl

 

[ripitup911]

wow this has proved to be a excellent read i am by no means a expert but i have noticed big differences in consistency of powders for example out of my 7mm rem mag all things kept the same and only changing powders with retumbo i was getting a ES of 65 on 10 shots and with VV N560 my ES was 17 on 10 shots. chrony is a gamma master chrony from shooting chrony's

 

[roberti11]

This thread started out with the concept of developing a load that will be competitive for 1000 yards.

Rather than just looking at velocity spreads I thought it might be a good idea and step back and look at the total picture... i.e. everything that goes into producing accurate ammo for competition

So I hope the following will not be considered too far of track for this thread, sorry it got so long winded…. J

I used to test my loads at 100 yards, but have found more than once that a good ½ min group at 100 yards, opens up to an unacceptable group at 300 yards, to save powder and bbl life I use a 100 yard target only for zeroing, after that all load testing is performed at 300 yards. I start with 3 shot groups and try to find the load that gives me the best vertical, I do not pay any attention to windage (unless it is extreme) because I always fire at the same aiming mark, I am only interested in one variable. When I get the best vertical, I will then move to 5 shot groups and adjust the load until I get the best vertical. To be competitive at 1000 yards I would not accept more than 1.5 inches of vertical at 300 yards, depending on the rifle I would prefer less than 1 inch (I shoot F-class with a scope and rest, so I cannot comment on acceptable groups for TR).

Load Consistency:
There are several things that contribute to this, and you really need to consider that you want the components for any load to all be as consistent as possible, that means that the SD for each measured component should be as small as practically possible. How many of these things you do will depend on where you are in your shooting career and what kind of shooting you will want to do. When I started I did not do all of these, but as time passed I added each of these processes.

A good friend of mine (well known F-Class shooter) told me I am not interested in 5 shot groups or even 20 shot groups, show me your 100 shot groups, because that is what I shoot in competition.

What he meant was that if you what to compete on a National or International level, every part of your load must be as consistent as possible. What we all dread to have the heaviest bullet in the batch, loaded into the lightest case, with hardest neck, and the lowest powder charge (ie the extremes of all the possible variations in a load). At 1000 yards that may take you from a shot in the 5 ring, into the 3, or worse

Again, how much work you do to achieve this will depend on where you are in your career, it is best that you do your best to be consistent within your practical knowledge and time limits and get out shooting, the rest will come with time.

Here is what I do, please feel free to comment and criticize as you see fit, and add any points I have missed

(1)Bullets are weight sorted into batches of one standard deviation, the bullets I use are very consistent, and not overly sensitive to seating depth, and I have stopped measuring ogives as I find this did not help me.

(2)Powder charges are weighed, I use extruded powder and have never found a dispenser that was consistent, I think that if you have a ball powder that works for you, then a good dispenser is as good as weighing, for the cartridges that I use ball powders have never been an option.

(3)Cases are weighed into lots of 1 SD, I know some people measure volume, but I have never found cases of the same weight to have significantly different volumes (I use brass from the same manufacturer and lot)

(4)Case necks are turned, I shoot a wildcat that is reformed in several steps, hence I do not trust the case neck to be uniform, I cannot comment if there is a practical reason to do this with match commercial brass, but since case neck tension is critical to performance I would have a hard time not doing this (See the following for the full story on case prep Http://www.6mmbr.com/jgcaseprep.html , and http://www.6mmbr.com/neckturningbasics.html )

(5)Cases are annealed in the same batch at the
start of the season, I have found this to be critical, again since I shoot a wildcat the annealing is a given, but have found this process to be helpful with other cases. If the annealing is done in a consistent manner it will yield a consistent case neck tension. (http://www.6mmbr.com/annealing.html)

(6)Runout (concentricity) I shoot a fairly tight match chamber and use quality dies an bullets and often ask myself why I bother, but in every 100 or so loads I always find at least one significant outlier

Points 1-5 are all parts of the reloading process that can be measured, and each will yield a data set with its own Mean, SD and spread. Keeping all of of these consistent will result in your 100 shot group with the best SD and spread possible, given your experience, time and equipment.

Again, I would not advise someone starting out do all of this as it may lead to more frustration than fun, and shooting in matches is supposed to be fun

This is also an excellent article, you can apply its principles to what ever the longest distance you have access to for load testing

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