Developing a precision load for a new rifle: step by step


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January 6, 2013, 12:42 AM
You get a new rifle in a new caliber. Where do you start and what steps do you take to develop the most accurate load for that specific gun? Please be detailed, and share your tricks!

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witchhunter
January 6, 2013, 12:54 AM
I start by choosing the bullets that I want to shoot, then process all of my brass the same way, choose a powder and and a starting weight. Measure that rifle's Max COAL, and I start at .010 shorter. By that, I mean .010 off the lands, chambered. Load 9 at each weight by 1/2 grain increments. shoot 3 each of 3 shot groups of each weight checking for pressure signs. Measure and average groups. You should notice groups getting smaller or bigger as velocity increases. Repeat this procedure for any other changes you make, powder brands, primer brands, seating depth. It's my opinion that the bullet and the seating depth usually make the most difference once you find a velocity that your barrel likes. Don't overheat your barrel and keep the bore clean.

Centurian22
January 6, 2013, 01:13 AM
I plan to try a slightly modified version of the OCW (optimal charge weight) concept.

http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134

I'm going to load three of each step from starting load to max, instead of just a single load for the first few steps. This is due to research revealing a potential accuracy node in the lower charge weights of my IMR4895 powder with my .308 sierra matchking 168gr BTHP. I'm not chasing max loads or velocity. I'm looking for better than factory accuracy (if I do my part) and economy. Therefore, lower powder charge equals more rounds per pound.

1911 guy
January 6, 2013, 02:15 AM
Agreed, but I use five rounds for groups instead of three.

Step one is prep all your brass exactly the same. Size them all the same, trim them all the same.

Step two is primers. I'm of the opinion brand doesn't matter as long as it's the same brand every time. No switching from WIN to FED without another workup.

Select your chosen bullet for your application.

Select a powder that gives the highest velocity at the lowest pressure for your caliber and bullet weight. Expect to spend a while poring over several reloading manuals researching this.

Load five rounds with the minimum charge, and five each at 1/2 grain increments up to the max load. Don't expect to shoot these hot loads, accuracy will likely begin to fall off before you get to them. You'll pull the components later at home. But you never know.

Begin with the minimum loads and shoot five rounds at a clean target at 100 yards. No kentucky windage or doping. Simply aim at the bull and make every shot count. Your group will of course of off the bull, but you're checking for size, not zero.

At some point, accuracy will begin to improve, then fall off again. Your rifle likes something in that window. Lets say accuracy begins to improve at "A" charge and falls off again at "C" charge. Your optimum window is somewhere near "B" charge.

In 1/10 grain increments, load rounds from "B"-1/2 grain to "B"+1/2 grain, five rounds each charge.

If no satisfactory results are found with any combination, select another bullet or another powder. I usually select another powder, unless I have reason to believe there is another bullet weight that is better for my need.

oldpapps
January 6, 2013, 02:32 PM
" Please be detailed,"

Asking an old f@r! to be 'detailed' is not a good thing :rolleyes:

The weapon is (factory) new or new to me. Before I trade or buy, I will have studied the subject, a lot. So I will have a good idea what I'm getting into.

The weapon:
Strip it down as far as prudent. Clean/scrub/burnish everything. This may be the time to clean the barrel. That process is to patch the barrel (breach to muzzle - if the breach is blocked/barrel set in the receiver, think M1/M14, insert the cleaning rod from the muzzle, patch and pull) with tight patches until clean and dry. Plug the chamber throat (cotton balls work well) and from the muzzle run a loose patch soaked with Butch's Bore cleaner, plug the muzzle and let it set. (I do this outside on my pick nick table, that stuff stinks!) After a bit, pull the plugs and run patches until no green is on the patches, repeat the process until no green is on the first patch. On older/well used weapons, I sometimes will run a nylon brush down the bore during this process. Finish up with some Hoppies to kill the stink.
Put it back together and oil/grease as needed. Special care taken with the actions lugs and fit into the stock. If it doesn't look like a very solid fit, contemplate 'glass bedding'. Moving on. Is the stock in contact with the barrel? Is it supposed to be? Deal with it as needed. Seal wooden stocks before continuing. With all screws/bolts firm to tight, look at the sighting system. This is the time for any improvements. Assuming the sites are OK and tight, the weapon can be considered ready.

Ammunition prep:
Obtain/find or select a quantity of brass in or from the same lot.
Tumble/polish as needed. I want to see any imperfections in the brass.
Inspect and sort. As I do this, I check the web for beginnings of head separation (I seldom buy NEW brass).
Lub and full length size. De-prime by other means if the brass has crimped in primers first and remove the crimp ring too.
Dump the brass into the tumbler with steel pins, Dawn soap and water. Tumble over night, rinse with clean water and dry in oven (preheat the oven to 250 to 300 degrees, put the brass on a towel on a cookie sheet, turn off the oven and put the cookie sheet/s in the oven. When the oven is cool, the brass is dry.)
Trim all brass to length, inspecting each casing. De-bur in and out.
Hand prime all cases.
I have not discussed annealing at this point. That is another complete subject.

We are getting there.

The Loads:
From a known and trusted source, pick a starting load for the selected bullet weight/type and powder. (I tend to use 748/IMR4895/H4895/Varget/4831 powders. The load is the determine factor.)
Over all length determined by several factors. Does the bullet have a canalure? Type of magazine/feed system. Looks. I like/want a minimum of one bullet diameter of bullet in the case neck.
Load 3 to 5 rounds. (As my range is just outside my garage door, I load and test, one sample at a time.) Log all information. Test fire these loads over the chronograph, record everything. Look over each fired case, primer condition, soot, whatever. Log it if note worthy. If being fired in an auto-loader, does this load fully function the weapon? If not, what didn't work? Was the measured velocities what was expected?
Repeat this process with increasing charges of powder until velocities/recoil/ANY pressure signs are beyond what is desired.

Analyze the collected data. I put it on a spread sheet. Pick a loading block that gives the most desirable results. Consistency in velocity and smoothness of functions.

Move on to 'fine tuning' the load for optimal accuracy. I normally start shooting at 25 yards. (I can walk to my target stand.) This gives a quicker 'zeroing' of the sights and general idea about how well or poorly the finished load may be. Move the target out to 100 yards. (Now I have to used my 4wheeler, it is not a direct 100 yards to get to the 100 yard target stand, out, around over the bridge, up the hill and over and finally down to the target. A simple straight visual view with maybe 300 yards of ground travel to get there!)

Differing weapons/calibers will have very different potentials. I had a 7.7 Jap, late war production rifle that I was happy to get 3 shots inside of a 4 foot circle. The rear sight was a 'peep'' that was welded to the action! Had a single heat treat 03 barreled action that would put 173 grain gas checked lead round nose in two inches shot after shot. Rainbow, 1500 to 1650 fps. much slower and they lost stability. Didn't trust the steel for any more velocity, lead loads or not.
Don't expect to shoot as well with that .460 Weatherby loaded with full power loads of 510gr full patch bullets as you can with that .222 Rem X40 and 45 grain HPs.

Nuf babbling. Told you, never give an old f@r! the go-a-head to babble.

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