Originally Posted by
Larry Gibson
StarMetal
Let's talk accuracy also. I agree it is easier to get accuracy with slower twist, or even with slower velocity in slower twists. I think any defects in the bullet or the reloading procedure are more forgiven in the slower twist.
This is exactly what "amazes" me as I posted. Just what exactly is it that you think "forgives" those defects? It is the lessor RPM of the slower twist. That's pretty plain to see isn't it?
Now let's talk about the accuracy. Let's leave the easier part out and just talk the actual group. Will a slow twist accuracy be more accurate then a fast twist one?
No it won't Joe given equal velocities and equal stability. However given equal velocity the slower twist will give equal accuracy at a higher velocity. I have proved that over and over again with the extensive testing of the .308W in 10, 12 and 14" twist rifles. I get the same accuracy at 2500+ fps in the 14" twist that i get at 2200 fps in the 12" twist and at 1900 fps in the 10" twist. Do the mathc joe, the RPM is close to the same for all of them.
Let me put it to you another way before you start to think of your reply. Many jacketed bullets shoot more accurate smaller groups when pushed to the limits. Not all them, just many. See what I mean? Nothing to do with ease.
There you go again, off on tangents about J bullets and cars:-) Did you ever consider, in your anolgy, that some J bullets are impossible to shoot at HV because the blow up from to many RPMs? I thought not.
Many have mentioned no need for HV loads. I've wrote this before, but here goes again. I only got into cast bullets because I got satisfaction of making my own bullets. I never started with the pistol/shotgun powders. I merely wanted to replace my factory jacketed bullet with a cast one. I started right off with rifle powders and at the 1800 fps level and up. I never shot below that only rarely. I bought a 45-70 good while back. Bought the RCBS 405 mould for it. Well the first load I settled on was a pretty stiff one using 4895 powder that got that bullet up to 1850 fps from my carbines 20 inch barrel. Yes, that curved steel butt plate bit me pretty good. Only recently have I dropped that down to 1450 fps after realizing I didn't need to push those big slugs as fast as I was. I did harvest a flue of deer with them though. I guess the HV with cast bullets in rifles comes pushing Chevies hard and fast on the street and track.
Funny how we agrue over HV in rifles, but not in handguns. You or someone will say well they don't have fast twists. Yeah some of them do. Like my 30 Luger and I push it too with accuracy. No specialized loading techniques there one iota. Just the bullet and the powder. And yes it doesn't have the rpm of the Swede at HV.
There in lies the reason we don't discuss loads such as your 45-70 and handgun loads. They do not exceed the RPM threshold, most do not even enter the RPM threshold range. There fore they should shoot well, all other things being done correctly for a cast bullet load. BTW; In my Siamese Mauser 45-70 (it has one of them "crappy" E.R. Shaw barrels on it) I have shot the Lyman 457483 (GC'd 390 gr fully dressed) at 2300 fps without pressure problems. The RPM of that load was not quite 80,000. Thus even with a slightly faster twist your Marlin load still had less RPM. I have to tell on myself here....There was some adverse "pressure" ....it was to the shoulder as you mention. As a matter of fact it was down right fierce off the bench:-(
Larry Gibson