7mm Remington Magnum Handloads
This was the first cartridge that I reloaded for, and I took my first deer with it. Once I have a good collection of ready deer hunting rifles, I think I will have some accurizing work done (fiberglass stock, free-floating, squaring of the action, and probably a new barrel with a shallower throat), and then I will develop a new, accurate load for it.
|Deer Hunting, Sierra 140/160 gr. HPBT GameKing|
I have a box of Sierra 140 gr. HPBT GameKing bullets, #1912. It's a tougher bullet made for higher velocities. It seems like it would be an ideal bullet for the 7mm Remington Magnum, and it could especially be used for a little longer ranges. But not too extreme, because it doesn't have the greatest BC. It has 1500 ft-lbs of energy out to 350 yards.
Huh. Sierra also makes a 160 grain version of their HPBT GameKing. By the time I am ready to experiment with this bullet, the rifle will be ready for longer ranges. Would I be better off with a heavier bullet to extend the range? Not really. The BC isn't so much better that the heavier bullet ever overtakes the lighter one.
The 7mm Remington Magnum has plenty of power. For whitetail deer, I want a cartridge with reasonable terminal ballistics and good accuracy. The first load I've developed for this used the 150 grain Nosler Ballistic Tip with Hodgdon H4831SC powder.
I then decided to try the 140 grain Nosler AccuBond with H1000 powder. I had heard that they were more accurate than the Ballistic Tip and nearly as effective as Partition. I haven't really noticed better accuracy.
Now I am trying Hodgdon RETUMBO powder, again with 140 grain Nosler AccuBond. It is closer to being a compressed charge, and it yields faster velocities. With any luck, it will turn out to be even more accurate. I just loaded up a bunch of this, and even at 73.6 grains and the long COAL, the powder is packed in there pretty tight. RETUMBO was obviously made for this cartridge.
I may be well advised to find a different bullet for this purpose, one that can be seated more deeply and still come close to the lands in my rifle. I may be able to get more accuracy by seating closer to the lands. Is there a 140 grain Nosler Partition? Should I consider an offering by Barnes? I should buy a few things and see how they reach into the throat.
Sierra MatchKing: I am a little disappointed with these. I would have expected them to be more accurate than Nosler's cheaper offerings, but they were not. I've noticed a great deal of lopsidedness at the meplat, and much more variation of overall length. I might want to consider getting a meplat uniformer, which were undoubtedly designed specifically for these bullets.
Nosler Ballistic Tip: I am quite pleased with these. They are more accurate than my MatchKings, and I was surprised to measure at most .001 variation in overall length.
One problem is the length of the bullets. They have a long ogive taper. When seated to touch the riflings, the overall length is 3.414, which does not fit in my magazine. I have settled on an overall length of 3.385 inches, which puts them .029 away from the lands.
Nosler AccuBond: They are supposed to be more accurate than Ballistic Tip, but I haven't really noticed. Theoreticaly, this is due to the process which eliminates voids in the lead, yielding a better balanced bullet. Like the Ballistic Tip, they have had almost no variation in overall length. I have also heard they have terminal ballistics near that of the Partition.
These bullets have an even more slender taper. Touching the lands, the cartridge would have to be 3.455 inches long. At 3.385 inches, they are .070 from the lands. They seem to be performing reasonably well at this distance.
Ooh! I can get factory seconds from Nosler!
Nosler Partition: In addition to the excellently designed structure, these bullets appear to be made very precisely. I have not loaded or fired any in 7mm Remington Magnum, but I have gotten some very good groups with then in my brother's 243 Winchester.
Hodgdon H870: I did use a bottle of this with 150 grain bullets. I was quite puzzled, since the starting load and the maximum load were the same, no matter who I checked with. I couldn't guess why that was, and it gave me no room to experiment with the charge to find the most accurate load. H870 is also disappearing from shelves, being basically discontinued.
Hodgdon H4831SC: To date, this is the powder I have the most experience with. It measures quite well in my Lee Perfect Powder Measure, and lot to lot density variations have been undetectable. It is one of Hodgdon's Extreme Rifle Powders, giving me temperature insensitivity, a very important consideration for a hunting load.
Hodgdon H1000: I have just picked up a bottle of this. Like H4831SC, it meters wonderfully and the density was right on. It is also an Extreme Powder. I am trying it because it is a better match with 140 grain bullets than H4831SC is.
Well, I got sure signs of overpressure with H1000 today. Difficult case extraction at 69.2 grains, and some suspicious primers before that. Modern Reloading says to back off a full grain, which is luckily just enough to keep the fairly good group I had at 68.1 grains. I shall have to experiment with some lighter loads.
Hodgdon RETUMBO: This is a new Hodgdon Extreme powder. In 7mm Remington Magnum, it yields consistently faster velocities than any other Hodgdon powder, and the max charge is a compressed load for all but 175 grain. If I wanted to, I could use this powder for every load in this gun. And that's a good thing, because I now have a huge supply of it.
Accurate XMR 3100: I just bought a bottle of this at a gun show, and I intend to try it out with the MatchKings. It yields the best velocity for 150 grain jacketed bullets. The guy I bought it from seems to think it is very accurate. It won't be a compressed load, but it should fill up the case nicely. I probably should not use this for hunting ammunition, as it is probably more susceptible to temperature variations than a Hodgdon Extreme Powder is.
Well, apparently I have been spoiled with Hodgdon powders. The density of this 3100 is way off from where it should be, and my powder measure is giving me a much wider variation than I am comfortable with. I've pulled the bullets and I will do this again with my digital scale + trickler.
Alliant Reloder 22: I have not tried it yet, but I bought a bottle of this. It is a very short grain extruded powder, so it should meter well.