Re: 30 cal 200 nosler accubonds
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Have you tried any faster burning powders in your 300 Win Mag and 200 gr Accubond? I am doing some load testing with a couple of 300 win mags with this bullet. I am finding that I can get just as high of velocity with burning rates like IMR 7828 and RL22 but with 6 or 7 grains less powder than H1000 and minimal load compression at magazine length. I would think that you would have to cram a lot of Retumbo in the case to get max velocity.
Just some food for thought.
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As yet I have tried only H1000, my rifle is showing a real preference for bullets seated towards the lands, I would not attempt to try and hold at say .005" or less behind the lands as tolerances on differnet bullets, even from the same batch can cause variations sufficient to make this too indeterminate a method for me at least.
When seated to say .030" from the lands, the Accubond leaves sufficient space in my own cases so as not to have excess compression with 78 grains of H1000, yes there is mild compression, but nothing that troubles me. (As my rifle is in Win Mag it uses a shorter case than your own RUM so I have etra length capacity in my mag box than you will have for longer O.A.L rounds)
I agree that in an ideal world the rifle should shoot well with all factory ammo, no matter what the seating depth. At present however I am dealing with a factory spec rifle, with factory fitted barrel, as such this rifle will be intended (thorated) by the manufacturer to be able to accomodate, in safety, any of the commercially available factory ammo, which as far as I can see in .300 Win Mag ranges from 150 grains upto 220 grains.
Given the longish freebore, the use of a large number of these rounds will be a hit and miss affair as far as accuracy goes, you may hit lucky and find as least one, hopefully more, factory rounds that shoot well in accuracy terms. As an alternative to this is to do what most bench rest guys do and load to suit your exact rifle, in my case this has shown a preference to go close out to the lands. I would qualify this by saying I personally would not load to enter the lands, some do I know, but too many problems can arise this method, and for hunting IMHO it is best to avoid this if at all possible.
I personally see no problem in loading long, as long as common sense and care in load development is followed, after all you are fune tuning the ammo to your particulare rifle, much the same as race drivers fine tune the engine for their particular race car.
I have found, with load/pressure testing with Rel 22 that great variation can arise from cannister to canister for the same charge weight, no problem if you back off and re-test with each new batch of powder used, as probably you should do, and no problem if you are using low end loads, but if you are up to top book / pressure loads, a variance in burn rate can lead to pressure problems.
I have not tried it yet but beleive around 80 -82 grains of Retumbo will be required, as you say, this will certainly fill the case, to what level I cannot say, maybe with re-sized fired cases that load level will be no problem, others who have used Retumbo will know far better than I.
Maybe another way to go would be the use of H870, now discontinued I beleive but stocks of which seem still available or 869, however I have no experience with either of these, certainly being a spherical powder the lack of interstitional space in a charged case should permit maximum charges to be used.
I have both Rel 25 and IMR 7828 to try and will do so when time permits. Do you know if 7828 and 7828SC produce the same velocity for the same charge or is there a difference in burn rates, I am guessing the differnce relates solely to its ability to meter better much as with 4831SC