How to fine tune a good 100m load to shoot at 200-300m?

stecad

Well-Known Member
I have a good 100m load for my 308 Sauer (Hornady 150grn I/L, 44.5grn N140, loaded to cannelure and finished in a Lee collect crimp die) which will clover leaf if I do my bit.
I have shot it out to 200m but not approached this scientifically - chrono, tweak the powder, change the OAL.
I plan to do this in the Spring and would like to understand are there any parameters that would help develop the consistency of the round beyond 100m.
I also have an excellent load with Nosler BTs which do allow me to play with OAL. I don't see changing OAL as a real option with cannelure heads.
Bound to be a trade off - just wandering what experience others have.
 
Is not the first question - does it need tweaking? If you're getting good results at your chosen distances, what is the issue? I'd be shooting a series of groups at 200, 250, 300 to create a dataset to work from before I tinker.

In general terms, you should be ensuring the standard deviation on the velocity is as small as possible and perhaps play with neck tension to reduce this if necessary, but if you're cloverleafing at 100, why would it not do it at greater range when the velocity SD is small.
 
Clover leafing at 100 yards is mighty fine performance - bench rest standard. As previously said shoot what you have at 200 & 300 & look at your group sizes there - you may be surprised how well they perform - some bullets take a while to stabilize in flight so it is good to see what happens at the different ranges. Once in stable flight bullets usually stay stable until they slow down into the trans sonic range which is out at long range for most chamberings.
The groups will be bigger at long range of course & hence easier to measure group size. Wind & target visibility issues enter into the equation but you will become a better rifleman for the effort & understand what is happening better.

Remember that three shot groups don't tell you much - the bigger the number of shots in the test the more accurate the results. 3 shots poor - 5 shots ok - 10 shots much better. You will see "fliers" & can then decide if they are your fault or not much easier with big numbers shot.

Ignore canelures - you can crimp bullets anywhere you like or not at all if you are just shooting targets - the important thing is consistency of neck tension before crimping & the degree of additional nip that you apply. Case preparation is all important - including the work hardening state of reload brass - annealing will help minimize that variable.

Ian
 
Change the zero to 200 yards.
Without knowing your rifle, velocity you are getting, game, normal distance, and type of sights, that is as good as I can suggest.

Start by moving your POI 2 inches high at 100 yards. That should be close to dead on at 200. You may want to leave it there, at a round number elevation at 100, but you won't know until you shoot it at 200 and 300 ( and further, if you can) without touching the sights.

But a 200 yard zero works well for me. +1.75 or 2.15 at 100 makes little difference to me.
If you are on at 200, your load, at 2,700 fps or so, should be about -7.5 inches at 300 yards.
Then shoot groups at 200 and at 300, making sure you are lined up vertically ( no windage adjustment needed ). Now you know how much to hold over at 300, or how many clicks up.

Once you know the real trajectory, you can play with a ballistics program until it gives you the same trajectory. If you have a BDC reticle, you can see exactly what the yardage is at each drop hash mark.

Burris article of different zeros ranges with BPlex reticle.
http://www.burrisoptics.com/pdf/BALLPlex.pdf
 
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just shoot your best 100yd load at 200-300 yds -your bullets dont know how far there going.
 
You might want to see how good a group you get at 50m , this 50m zero puts me dead on at 200m .
 
Hi JCS, many thanks for this. Just had a quick look and there is an excellent article on the forum at the moment.
"Long range load development at 100 yards" search string, but actually on the first page of the forum.
Sets out how to spot the best load to work with for development. Seems that clover leaf is not the best indicator - vertical string is. All seems logical now.
steve
 
I'm reading with interest as I'm currently tinkering with a new .308 load as well.
I'm using a 150g Nosler BT Hunting over 47 grains of BLC2.
Currently getting groups of around 1.5 inch, much room for improvement I think.
With a bit of playing around I'm hoping to significantly better this.
 
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Interesting contrast with Optimum Charge Weight OCW Overview - Dan Newberry's OCW Load Development System when talking about the sequence of shots. With OCW it's recommended to shoot a single shot at each target in turn so shooter fatigue is cancelled out. In the recent thread the argument is that the extra movement takes the rifle off each target so introduces it's own variations. Take your pick...
 
Find a load that shoots consistent small groups at 100 (sub half or quarter inch), prove it by repeating groups at 100 and yourself for that matter.

The same load will be fine at 200 , 300 etc etc
 
just shoot your best 100yd load at 200-300 yds -your bullets dont know how far there going.

My 100yd sub 0.3 MOA 55gr 22BR load shoots 2.5 inches for 5 shots at 525yds.
Could it be better? maybe, i could develope a 500yd load with a heavier higher BC bullet but it wont necessarily be more accurate and consistant.

Ian.
 
I have a good 100m load for my 308 Sauer (Hornady 150grn I/L, 44.5grn N140, loaded to cannelure and finished in a Lee collect crimp die) which will clover leaf if I do my bit.
I have shot it out to 200m but not approached this scientifically - chrono, tweak the powder, change the OAL.
I plan to do this in the Spring and would like to understand are there any parameters that would help develop the consistency of the round beyond 100m.
I also have an excellent load with Nosler BTs which do allow me to play with OAL. I don't see changing OAL as a real option with cannelure heads.
Bound to be a trade off - just wandering what experience others have.

Is this paper you are shooting? If not how will you adjust for something out at 185 (for example) looking like it is about to move in to cover.....

Tim.243
 
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