ORIGINAL: ColoradoElk
Hi everyone:
After searching for quite some time, I am the happy owner of a SAKO 7x64. As a metric round, I am having more difficulty than I thought locating reliable data for the bullet I will be using, the 156gr Norma Oryx. Norma privides data, but only for Norma powders, which are no longer exported to the US. My questions are:
1) I have heard Norma and Reloader powders are both manufactured by Bofors, and are identical (I have also heard Reloader powders are powders that don't meet Norma's quality control). For example, Re 19 = Norma 204 and Re 22 = Norma MRP. Does anyone have any input on this?
2) The case is very similar to the .280 Rem, and .280 Rem data can be used as a starting point for 7x64 development. However, from the Norma website, the STARTING load for the .280 Rem is 55gr of MRP, two grains HIGHER than the load for the 7x64. The max load listed for the 7x64 is 56 grains!?! There isn't going to be a whole lot of load development if I only have one grain to work with.
If you could pass along any comments, I would appreciate it!CE
RE 22 is similar to MRP, but there is some variation from lot to lot of RE 22, so it cannot be interchanged grain-for-grain except perhaps in starting loads!
I certainly agree with you that ONE GRAIN difference between a starting load and a maximum load is not anything to work with.
However, because "All rifles are individuals, and what proves to be a maximum load in one can be quite mild in another, and vice-versa",any maximum load you find printed someplace was the maximium in the rifle it was developed in, but no other. What does this mean? It means in order to have a maximum load for
your rifle, it has to be developed in your rifle. You take a "starting load," and work up your load in 1/2-grain increments until:
A. You get definite excessive pressure indications,
or[/b]
B. You geta particular load which is as accurate as you demand,and it is providing at least the velocityyou are willing to accept.
FOR EXAMPLE!!
OK! What's a starting load? I think it is safe to take the maximum load given by Norma, andREDUCE IT by 5%, and start with that charge. So, Norma says 56 is MAX? Then you start with 53 grains, and load up five rounds with 53, five with 53.5, five with 54, etc. etc. and shoot a five shot group with each. Use the charge that gives you the best accuracy without stretching a primer pocket so that the next primer goes in too easily! If you get to the point where there are definite excessive pressure indications, such as stiff bolt opening, really noticeable EXCESSIVE primer flattening (compared to idnetical primers from rounds you shot at the lower powder charge levels), you know you have gone too far, and must drop back to a charge at least 5% lower than this one!
Now the above is just an example, but this is my "load work-up procedure". I want a powder charge that is mild enough that my cases can be reloaded at least ten times before a primer pocket gets too loose to hold a primer tightly. Using this method it is POSSIBLE that your rifle's maximum load might be 60 grains, or it might be less than 56 (but not likely!!)
(I know for a fact that 56 grains of RE 22 will not prove to be excessive with 150-160-grain bullets in a 7X64mm, because I use 54 grains of RE 22 in my 7X57mm Mauser rifleswith 175 grain bullets for a MV from the 7X57mm of over 2700 FPS with my required 10-shot case life!) .
The reason why some data for the 7X64mm will showlower powder charges than the 280 REM is that the 280's shoulder was moved forward to keep morons from firing 280 ammo in .270 WIN. chambers. So the .280 holds a little morepowder than the 7X64mm.
(My old Hornady book gives 57.4 grains of MRP with a 154-grain bullet as a max load in the 7X65R in a bolt-action Mauser, and the 7X65R is just the 7X64 with a rimmed case.! MY 2800 FPS with this load, and the bullet is only 2 grains lighter than your Oryx.