Re: .224 custom 100 grain ULD\'s for 1000 and 500yrd benchrest
Reed, If you believe that firing five shots in 6 minutes would not overheat the 22/243 imp then I would stick with it, and not go to the smaller case. You mentioned that it is a 27 inch heavy barrel, and am curious what is the diameter at the muzzle?
I agree that there would not be much difference in barrel heat between your 22/243AI and 22/250 AI. You mentioned that you are using a load of 47 grains IMR 7828 with the 80 Sierra in the 22/243AI, and from my experience that would only be about 1 - 3 grains more than you would be using in the 22/250 AI.
I am currently using 46.0 grains Winchester WMR (ball powder) in my 22/250 Imp (28) behind the 69 grain Sierra, for 3430 fps out of a Shilen 24.5 inch 1 in 10 twist barrel that is .765 at the muzzle. I previously used the same barrel for 1600 shots with the 224 Clark, and achieved about 3,930 fps with the same bullet, using 54.5 grains IMR 7828.
However, although IMR 7828 gave either the highest or second highest velocities in my 224 Clark with the 60 - 80 grain bullet weights, I found that it was temperature sensitive, and the odd shot gave unpredictable pressure spikes, and have had similar experiences with this powder in a 220 Swift AI, and 25/06 AI.
Although many of the ball powders are temperature sensitive, where possible I use one for my field loads to try and limit throat erosion. Luckily in the 224 Clark, 54.0 grains WW785 gave good accuracy and a velocity of about 3850 fps.
I admire you "no pain no gain" approach with the 100 grain RBULD, which I agree would be terrific to use if it can be made to work. However, I must be a little more practical and would never build up a rifle around just one bullet. If for some reason the 100 grain RBULD would not shoot accurately, then the obvious "fall back" bullet is the 80 grain Sierra HPBT. However, in my .224 Clark at 3,700 fps if using a 1 in 6.5 twist it would be fairly whizzing at 409,846 rpm, and obviously under considerable stress.
Perhaps I should go and buy a skirt for suggesting this, but had you considered using a 95 grain RBULD instead of the 100 grain ULD. I believe it would still have a BC of over .600, and should have an excellent chance of being stabilised in a 1 in 7 twist barrel, and we already know that 80 grain Sierra and 90 grain JLK will work with that twist.
You can tell Richard that if he does decide to make some up 95 grain RBULD's then I would buy at least 500 to help shore up the initial order.
Richard mentioned to me on a recent phone call, that he can make up some 90 and 100 grain flat base 10 ogive hollow points. He said that they should be an excellent hunting bullet as they would have a .030 jacket and tight meplat, which would enable them to hold together and penetrate well. I told him that I would buy some, and send me some in his next shipment to me. Regards, Brian.