I've noticed there's a difference in coal between mfgs. That's only part of the equation. Brass volume throat and twist rate contribute the other factors. As far as lot numbers go there's usually not much change in max charge (less than .5gr in most test), compared to 1.5-2 grains of the same powder. Sierra #5 and #6 are way different as some coal has changed also for some reason? 1 BIG example is #6 book has 6.5prc w/107smk @ 2.955" (I think or just a little shorter) is a no go on it's to long of a coal! The bearing surface only goes into the neck about .080-.100" and the boat-tail takes up the rest of the neck.
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Book powder charge difference
- Thread starter C-130 Dude
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Mike Matteson
Well-Known Member
Yes it #6 addition. They are showing 1 x 12 twist rate. They are showing 35 grs of IMR 4064. @ 3550fps. My old manual is 1971 addition. Shows IMR4064 39grs, and a velocity of 3900fps. I have use this 2nd load of 39grs from the 1970's. No problem and just about a single hole grouping. The twist rate is 1-14.
No neither listed pressure. I don't really care about that listing. I work my loads, and watch other item showing me that I am getting to be overpressure. My swift I have held it to 3900fps loads. I read a long time ago it help to keep your barrel from burning it out. That was the big problem with the 220swift back when. I think they were using 45gr bullets @4200fps.
That was the big seller or push with the 22/250 that is wasn't a barrel burner. Then they come up with the 22/250AI case.
The only plausible reason I can come up with is that the older 4064 powder has different characteristics than the current 4064. Be great if the company would confirm or explain this....
Mike Matteson
Well-Known Member
Twist Rate!
Does 4 grains difference between a 1x12 or 1x14 twist make that much of a difference? I don't know. Something else???
Not missing anything at all but you made a valuable observation. These manuals provide reference data that was recorded on a given day under certain unique conditions. Use the data provided as a reference guideline. At the beginning of almost every manual I've looked at, starts out with the statement start out low and work up gradually. Never Never look at the MAX load and jump right on it. Having 60k psi going off right next to your face should be undertaken with the greatest of care. I will look at several load data sources when I start out with a new load. I use a ballistic calculator to give me velocity at the range I expect to shoot at game, I use the bullet manufacturers recommendations as to what minimum velocities their bullets expand best at. Then I work backward to the muzzle velocity that will give me that downrange velocity. Most times I find that my loads are well below maximum, provide me with needed velocity at range, and give longer life to my brass.
Mike Matteson
Well-Known Member
Neither do I. I just came across it last years. Looked into my old reloading manuals. Saw the difference. Then note there was a change in twist rates. I have used that old load im my rifle from the middle 70's.
Sometime I feel that people don't like the 220 Swift, and push the 22/250 or others. It's hard to beat in the 52grs to 55gr bullet weight. At one time I could almost get a single hole in the target @ 100yds. Nothing special about the workup in the loading of the case either. If you misssed, it was the shooter not the rifle.
That rifle was in M-98 action with a bow barrel and 24" long. Set up for a left hander. Me being a lefty. It was gone off the shelve in a sec. I got it.
Like has said before. Once I develop a load for that rifle that's what I stay with. If having a rifle being built I generally already know what bullet weight I am going to use, velocity that is shown on the reloading manuals. From there I work on getting accuracy and velocity out of the round.
The only thing I have change over the years it I put a lot more work into the case to set up to uses.
Several years ago I though that I had my reloading down pat. This the place to get your upcoming. Sure changing my way, after really reading here, and learn a bunch too.
