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Do you adjust powder amount or seating depth first?

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  • Do you adjust powder amount or seating depth first?

    I just got a few boxes of 150 grain Barnes TSX bullets to work up for my 30-06. Barnes lists H4895 as the most accurate powder, minimum of 48.5, maximum 51 grains. I usually work up batches of 3 rounds in .5 grain increments to look for the best groupings, then fine tune around that. Barnes also recommends these bullets be set a bit further off the lands than others, from .050" all the way up to .250". My question is which of these variables do you start with? 49 grains might shoot fine at .050" off the lands, but 50 might shoot better at .090" off. How many different combinations do you work up? Thanks.
    Never count your days, but rather, make all of your days count.

  • #2
    I work up a powder load first, then play with seating depth to fine tune it.
    ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
    I would rather have a mind opened by wonder than one closed by belief. ~Gerry Spence
    The last thing Alaska needs is another bigot. ~member Catch It

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    • #3
      Me too powder charge first. Very rarely will max charge be the most accurate.

      Also I seat my bullets to the COL recommended. Reason being my kids and grandkids are old enough to shoot and do often. I don't want one of them to grab a round for their Ruger American that was seated to match the long throat in one of my Weatherbys. Serious pressure from stuffing the bullet into the lands of the rifling could occure. We have 5 different 308 rifles in the brood and tailoring rounds for each and then trusting the grandkids to keep the right ammo with the right rifle is worrisome for me. So we will error on the side of safety.

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      • #4
        I use a chronograph and work on powder/primer combinations first, looking for a low variation in muzzle velocity.
        I seat TTSX/LRX at a constant 0.050" off the lands.
        For example, a 130 gr TTSX in .270 Win with IMR4350.
        5-shots for each load.
        Ambient temperature 45F
        Load Standard Deviation
        52.5 16.9
        52.7 10.6
        53.0 19.8
        53.5 17.2
        54.0 17.8
        54.5 4.6
        55.0 14.9
        So I would repeat the next day to confirm the low variation, by shooting loads 54.0,54.2, 54.5, 54.7,55.0
        Then once I have a low muzzle variation confirmed,
        next work on best group with varying bullet seating depth.

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        • #5
          I have used the suggestions from the Berger web sight and start with seating depth first if I have a rifle that I want to load past SAMMI spec. But, I think I am going to change. Here is why.

          I used a mid range powder load and fiddled with the seating depth. I loaded the same powder charge in three sets of 5 rounds. .050, .070, .100. I shot that at 200 yards. One of the three will have a significantly better grouping. Then, I worked up a ladder of progressively increasing powder loads. .2g for smaller cartridges, .3g for the big ones like the RUM. Each round was shot at 200 yards with the same point of aim, all these progressively increasing loads have the best COL from the previous experiment. There will be an accuracy node where about 3 shots will be very close and then open back up again. If that node is at the velocity I want, then I have a great place to start further tinkering or call it good.

          The above option is good if you don't have a good chrony, or use the ones that attach to the barrel. However, it assumes your rifle will tolerate a mid level load. I have two that have not and .1 off the land with a mid range powder load gave some pretty good pressure signs. In a new rifle, I tend to be more conservative now. Most barnes bullets do very well at .05. If the magazine allows, I load 6-8 at that length and start at a low load and work up to a higher load by .5g. or so depending on the volume of the case. It is safer and sometimes I find the load very accurate as I work up the ladder of charges. If I find a good accuracy node on my very first try, I can go back the second round and fiddle with the charges a bit more. It is much safer, but likely will take three trips to the range vs. two. The first loading is really just to check pressures as I work up a load. Once I know I can reach mid to upper levels of published data, then I can use the seating depth first then charges next type of scenario.

          Sometimes, I just don't want to go to the range 3-4 times and a 1.5 inch group is fine to shoot a moose. So, I load at SAMMI specs, try in .5 increments in 5 shot groups and find out if the gun will shoot. Usually a well made gun will shoot just about anything to 1.5 MOA. The factory rifles, not so much. I find a load that is pretty good, load 10-15 of them and go out again for some practice. If all goes well, I load up 20-30 and go hunting that year.

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          • #6
            I always verify feeding and chambering before I ever start to load. Always make a few inert dummy cartridges for die set-up and alignment and verify fit and function of rounds. Working upp powder charge before finding a working COL won't work.
            Loading manual shows what their test COZ was, and do you know if they tested in a semi-auto rather a universal receiver?
            Last edited by noylj; 02-27-2021, 16:24.

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            • #7
              Shotgunner has the correct method get your deviation down then adjust the COAL as needed . I use a old Speer 1967 load manual before the reduced load data in manuals today. You often have a high node and low node.
              You should find your node very close too 51.0 of 4895 with 150gr in 30-06. As a young hunter I loaded my 30-06 with 47.0 of 4895 with 150gr for deer it was very accurate and accounted for many deer.

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