Re: Need 22-284 Help Before I Find Out If This Gun Will Float
Gator, I agree with Reed, that the 75 Amax bullet could be a major part of your problems, and the post by 308 Nate gave you an excellent list of other things to check.
In 1972, I built up a 22/284 on a Sako L579 Action, and Ackley 33 inch CM barrel. The case neck was shortened .020 on my gunsmiths suggestion, and fireformed cases had a case capacity of about 63.5 grains, which is almost identical capacity to the .224 Clark (cap. 63.8) which I built up in 1988.
The initial groups in my 22/284 were good, but then I encountered problems with erratic pressures and lack of accuracy, that I never resolved prior to the rifle being stolen some 10 years later.
The one of the two major problems was excessive barrel fouling from the bullets that were coming apart in the barrel and in flight. This was evidenced by comet tails on the target, and in some extreme cases by keyholes, and the copper streaks on the lands at the muzzle. From the evidence submitted by you, I think that could also be one contributing cause to your inaccuracy.
Switching to the 80 grain Sierra HPBT may assist. Many other users of the 22/284, 22/6mm AI, 224 Clark, etc have reported that it is the only bullet in that weight range that they found would hold together at velocities of 3,600 fps or more. I believe that Richard Graves Wildcat 80 grain ULD bullets will also hold together, as in my discussions with him, he is well aware of the problem, and has designed his bullets to overcome this. (I also have his 80 and 85 ULD's in transit to me at the moment).
Powders such Reloader 25, H1000, Vihtavouri N170, Ramshot Magnum, which are all similar in burning rate, should give about 95 - 100% loading density a maximum pressure with the 80 grain bullet, and in my opinion these powders are better suited than slightly faster burning Reloader 22. Depending on your case capacity, you may just fit enougth Hodgdon Retumbo in to make it competitive.
I am not sure how you have throated the barrel, but I believe that you will find (like I), that the Rem 700 Short action with its magazine length of 2.800 inches, will prove too short to allow the proper feeding of cases from the magazine, if you chase the lands as throat erosion occurs.
Luckily in my .224 Clark, the 69 grain Sierra would still shoot acceptably with about .150 inches of jump to the lands, but this is less likely to happen with the much longer VLD style bullets. My next 224 Clark will be based on the Rem 700 Long Action to overcome this problem.
The other major problem that I experienced in my 22/284 was that the case necks would not expand reliably, despite being regularly annealed, and caused pressures to spike unpredictably. However, I have not heard others experience this problem with the 22/284, so I believe it was related to those 2 batches of 100 cases (each) that I used. I certainly did not experience similar problems with the .224 Clark, or other cases.
My personal experiences with the 22/284 and .224 Clark were like chalk and cheese. However, I still believe that the
22/284 properly set up should work well, providing you use bullets that hold together, and with powders of the correct burning rate for those bullets. Good luck, Brian.