How to work up load? 3 boolit diameters + 3 powders - your approach?

[westcoasttransplant]

Hi,

I am starting playing with loads for a 45-70 marlin (ballard not microgroove) slugged at 0.457 (only had caliper and not micrometer).

I have 405g boolits cast at .458, .459, .460.

I have trailboss + 2 higher velocity powders I want to play with. Will end up with a plinker with trailboss and then a faster powder for a goal around 1400-1600 fps for deer/moose.

I am a bit over 1hr from the range and pay $30 per day to use the range.

I have never worked up loads with 3 different diameters before. Usually I just compare powders which is easy. Start low and work up for each load and compare most accurate load of both.

How do you recommend doing this with 3 boolit diameters?
A) Start with 1 powder and 1 diameter and find optimum load and then use that powder load to compare the other 2 diameters?
B) Start with 1 powder and work up most accurate load for all 3 diameters and then once found most accurate diameter compare use that diameter boolit with the other powders (leaning toward this as approach - requires 2 days at range - certainly not the end of the world) - thinking starting with a fast powder first day to chose diameter and then use that diameter with trailboss + other fast powder to compare with most accurate load from day 1?
C) Working up 3 powders with 3 boolit diameters at the same time is fine by me but I am not sure if that is the best approach as it will use a lot of primers, powder and brass.

What do you do?

[NC_JEFF]

I think I would try the .459 boolits to start with. I don't have any Trail Boss loads but from what I see posted here people use it in almost anything. Once you find the best powder/primer/seating depth combination, try a few different lubes. If .459 works out really accurate for you, size the .460s to match them. I hope all the boolits are the same style and weight or this may a fairly lengthy test.

[westcoasttransplant]

Thanks.

They are all RCBS 45-405-FN+

For trailboss I have my load info. Honestly I wish I could stay with my Unique loads as they were accurate and dirt cheap but some recent reading of a couple reports of suspected position sensitivity has scared me away so trailboss it is. My "faster" powders are Varget and H4895, both of which I have loads for as well. Just going to have to decide do I want 1200-1400 or 1400-1600. Might aim for a bit on the slower side as I don't want these boolits to just punch neat holes though and through the animals. In my neck of the woods most shots are well under 100 yards.

[Scharfschuetze]

If you cover all the permutations possible here, you've got your hands full. Even though it may add weather and temperature variables, I certainly would plan on a couple of trips to the range to do it properly given recoil and fatigue factors for the number of rounds needed in a complete test.

Whatever you decide, use the scientific method with fair attention paid to each option.

My approach would be:

I would run at least three ascending powder charges under each boolit diameter with each powder that you want to test for each goal that you have set. Perhaps just select the average velocity between the low and high velocities that you have set as a goal. That'll reduce the number of groups needed for a valid result.

I graph such projects and in your case you can certainly graph your results with each boolit diameter coded a unique color for each of the powder types that you plan to use. That'll give you a few charts and give you easily read results that you can base a good decision on.

So what are you going to base your decisions on? I would suggest, if you have a chrongraph, ballistic performance and uniformity for each powder charge and boolit diameter, and of course group size. While your projected short range use may reduce emphasis on ballistic uniformity, if you want a really good load, you'll pay attention to it. While it may sound like over kill, I would also plan of basing your data on 10 shot groups as smaller samples may not tell you the truth. This way you'll have a quality load you can rely on and not just some plinking load that may or may not be repeatable.

When you end up with a diameter and powder decision, confirm that it is a repeatable result that can be relied on... on demand.

If you're lucky and you end up with a load early on that meets your goal, then be satisfied with it and drive on and save some time and components; although curiosity may dictate completion of the project.

[StrawHat]

(deleted duplicate post)

[StrawHat]

Have you slugged the bore of your rifle? That is where I would start. Find the bore diameter and use the boolit that is at least equal to that diameter.

Kevin

[leftiye]

Sounds like you have nine different combinations to test (if you can't just choose one powder on a criteria).

[btroj]

To help keep it simple start at .460 for size. It is what is most likely to work well.
Get the TrailBoss load workng first. Get used to the rifle. Shoot it a bunch.
Decide on a powder for the 1400 to 1600 fps loads and work up a load with it. I would be very happy hunting deer with a 405 gr bullet and around 24 gr of 2400. Gonna be around 1400 fps and should shoot well.

[Foto Joe]

I've just finished something similar with my '94 Marlin 44 Mag and a friends Marlin 336 30-30. I would suggest taking a cleaning rod and a bore brush wrapped in ChoreBoy with you. Pull the bolt every ten or twenty rounds, patch it out and check for leading. You're pushing a big heavy boolit out of the tube at a pretty good clip and without a gas check you run the risk of screwing up your testing by leading a barrel. Ten shot minimum strings are a must and a chronograph will help you calculate the efficiency of the powder burn. Some powders you may never be able to get enough case volume to get efficient burns before you over speed the boolit and wind up with leading.

I tend to agree with starting with a larger diameter boolit although I'd probably choose the .459 as a starter. Personally I'd save my TrailBoss for the end as it won't be your hunting load and will more than likely shoot reasonably well with whatever your final boolit choice is. I use 50 yards as my preliminary distance and disqualify loads that can't print at that distance, they won't get better by doubling the range. I also write the load data and distance on all targets and take them with me when I leave so I can lay them out and examine groups at home.

Start your charges at the minimum and work up from there, cast boolit load development is an art form. Given the distance to the range and the expense of using it you might also want to consider taking your press with you mounted to something like a 2"x6" and clamped down to a shooting bench. A cardboard box laid on it's side can work as a wind shield for your scale if the wind isn't howling too hard.

[groovy mike]

Half grain increments from book minimum up through midrange with each boolit with each powder. Why would you want to shoot less?

[Foto Joe]

With a monster cartridge like 45-70 I think you're safe bumping up 1 full grain per load. Once you find one that works you can bracket it +/-.5 to dial in.

Use what ever method you're comfortable with and works for you.

[mdi]

Process "A" starting with a .459" bullet...