Hoot wrote:Thanks for the images TT. Looking at them, I'd say the 350s might like even more velocity to get them into the sweet zone. Not sure is you can achieve that safely, but perhaps WC may have already found it and can chime in. When I referred to 1680 as a "Gentle Giant" I meant it. It's slower turn on seems to make it a lot easier on the brass, at least the ones I was using. That's not saying you can't get in trouble with it. If the stock 450b had a slightly faster twist, you probably could get heavier bullet groups to tighten up a little more at lower velocities. That is all fine and good, but the truth is any of those shots would put meat on the table.
Could you measure the average bullet length after you size those 350s? In the case of the 325 Barnes Busters, which run .90 inches long, QL says that seated to 2.26 COL, you can get a maximum of 46gr of 1680 in there for a predicted velocity of 2120-2140 fps depending upon which start pressure model you use. Both start pressures yield predicted maximum pressures in excess of SAAMI, but within the generally accepted maximum limit for .284 Winchester. I must emphasize that those values are for a 325gr bullet, not a 350gr though.
Good Work there!
Hoot
Yup, it sure seems like he can get more velocity. TT, as you up the powder weight, pay close attention to marks on the base, from bolt thrust. At 41gr, you are not reporting any and that's normal. Using a sharpie, will show the marks (Big-Time), when you finally get them, that's a sure sign to back off some powder. Also, measure the area just ahead of the Web, you can tell the spot, because that's all the further south, your sizing die sizes. Go for about .0015"+- expansion. If the case starts dropping on the mag, you've got too much pressure for that chamber (its sticking in the chamber, before it extracts). In that vain, look for the extractor marks on the inside of the rim. When you have to much pressure for that chamber, you may not be at MAX pressure yet, but you will have to back off the load, to get the gun to cycle.
You sound like an experienced Reloader, so pay attention, do your job safely and you may break 2000fps and even closer to 2100fps. I've seen 2100fps/350gr, but not all chamber will shoot to that number.
TT, you may indeed have seen benefits from the virgin brass, they are all Annealed at the factory and you may need to do that often, if you start to see spring-back from those heave crimps.
Your thrilled by this experience and you need to be, you're doing Yeomen work here and you're doing a good job. I just sized a batch of those Interlocks for Gunny and his LM. I bet he's going to see speeds over 2500fps, which is why you "Might", have room for more speed.
Hoot, as for a tighter twist, if you knew you were only going to use bullets heavier than 325gr a 16t would be the trick, but as we have so many choices the 24t was a trade-off, for the notion that everything will work well, some even much better than others (witness, sub moa w/250gr-ftx).
TT's 1.5MOA+- groups, are what, 4.5" at 300yds, considering that an adult deer chest, here in Michigan, is at least 18", for a kill zone (5" in Texas..wink), I'd diffidently say, that that would be meat on the table (to quote Hoot), like no 300wm could ever do at those ranges, with a chest shot! I might save those 350gr bullets for Elk, Moose, Bison, and the Big Bears. But at ranges of at 300yds and in, make the shot, Bang-Flop on anything in North America, the only thing left to do, is getting out your knife.
Hey, I just thought, the mean range for the 45-70, during the old buffalo days was 300yds. Keep in mind, before you get done, your going to smoke the shorts off the 45-70 GOV, that was using a 405gr lead bullet, in a 32"+- barrel and you'll beat that energy, hands-down, with a 20" barrel or even a 16 incher. The factory loads are advertised for Rem, Fed, Win, for a 300gr w/24" barrel at 1880fps!
Humm..
..t