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Developing a new steel load

Discussion in 'Shooting Related Threads' started by joe kuhn, May 22, 2009.

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  1. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    Here are the steps we go through when developing a new load. Main reasons to do this are: 1) We're seeing a shortage on favorite powder Universal Clays. 2) Blow through on roof of wad's powder cup due to double base powders with nitro. 3) A more valuminous powder will give us a tighter wad seat for better ignition.

    Single base powder to test: Solo 1250.

    1) Find comparable lead based load. See above link for STS hull, 1 oz shot, AA wad.

    2) Note range of mfr loads: 21.3 gr @ 6400 psi, 22.3 gr @ 7200 psi, 23.2 gr @ 7900 psi, 24.2 gr @ 8700 psi. Speed range is 1150 to 1300fps.

    3) We know steel will increase the pressures, but at the pressure range we're seeing above, 6400 - 8700, we can take the increase.

    4) Hand weigh the shot and powder on one scale, use once fired hulls and make 5-6 per recipe. Powder weights for 1 oz of #7 shot will be 21, 22, 23, 24.

    5) Send out to favorite testing site, which in our case is Tom Armbrust here in IL. It's $5 per shell. Since the top and bottom usually have the most variation as measured in standard deviation, we could cheapen it up by throwing out the limits. In this case, I'd like to get the info, so $100 it is.

    My own personal goal is 1225 fps which is right in the middle of the lead load range of 1150-1300. 21-24 grains should cover 1225 with steel.

    Another guy is doing the 1-1/8 oz load, but we're going to do it all on the same scale.

    Not sure what primer to use. Should check on available/price with supplier.
     
  2. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    I plotted the Solo 1250 data from the mfr. The speed and pressure 'curves' are straight lines. Assuming steel is the same, we could just test endpoints and draw the line for everything in between. In this case the cost would come down to 50 bucks. 21 and 24 grains. When you think of it, that's quite a big range.
     
  3. Neil Winston

    Neil Winston Well-Known Member

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    Joe, does Tom's equipment give a picture of the pressure curve or just the maximum? I do remember some reloaders on Waterfowl.com did the same sort of calculations you are doing and got some surprises when Tom tested the loads. Their finding was close to what I find, that everything is fine for while as you add powder, but when pressure gets very high, then it gets very higher in a hurry.

    Neil
     
  4. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    Tom's data is raw - you get a number for each shell, so averaging and plotting is up to us. (We also have to subtract his ANSI adjustment, if you know what that is.)

    Good point about the pressure curve arching up. I believe that's evident in the data for 1-1/8 oz lead & Solo 1250.

    Steel is a different animal. If you vary only the shot material from lead to steel, you get a higher pressure level across the board. With a curve arching up, we surely need to test this thoroughly to expose that upper limit.

    I'm convinced to go back to testing the full range: 21, 22, 23, 24 grains.

    Regards.
     
  5. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    We use special wads with extra thick petals for steel. It's not a problem. They're more expensive but steel is $1 a pound and hasn't changed in years.
     
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