by Apollo » 17 Jun 2018, 3:58 pm
Well, let's put it this way.
In every calibre and rifle I have and the same for my mate. I have a Hornady OAL Case and every different bullet I may use I measure the maximum length that bullet can be seated into the case and touching the lands so that becomes my starting point. Now, all my target rifles are "single shot" so they can be set up to have the bullet jammed (say 0.020") into the rifling but since I use "Soft Seating" which means not a great deal of neck tension the bullet is pushed back into the neck by the process of closing the bolt. It varies and some varmint rounds have a lot of neck tension so I have to find the point where I don't need to apply pressure to close the bolt.
With some rifles like my Tikka T3 a long seated bullet in a case touching the lands still fit's in the standard magazine. The likes of a CZ 527 I am restricted by magazine length so a bullet seated to touch the lands is too long to fit in a magazine. However, I have started there in the past with say my CZ 527 .223R Varmint to test loads and find the ideal seating length. On some rifles like my Sako 85 .243W that I also use for single shot target shooting I can make a long seated bullet in the case and use that as a "single shot" by just sitting the round on top of the magazine and push feeding it. The CZ's don't really like push feeding as they are a control round feed which like to pick the round up from the magazine.
Anyway, my method is still the same. Test loads as either jammed and/or just touching and work up a powder load for best accuracy at either 100 or 200 metres. Then I adjust that best accurate load with seating depth. Very easy for me as most all of my reloading is done with an Arbor Press and In-Line Dies which I can have sitting right beside me out on the shooting bench. I also use a Chrony during the first development stage simply to give me an idea of velocity and what changes then that's the last I use a Chrony.
Working on Varmint Rifles and Target Rifles is two different stories and that in itself is a whole new story for discussion sometime.
Not one of my Varmint Rifles has rounds that are jammed or even close to the lands, Be it may that it was just the way it worked out but in my view for a Hunting/Varmint Rifles do not ever have rounds that are close to the lands or jammed as it is just looking for trouble. If you get the measurement incorrect you might just end up with a stuck bullet in the chamber and powder everywhere if you have to extract the live round for any reason. Not a safe practice,
Again, might just be my luck but the likes of the .22 Hornet the rounds ended up quite short of the lands for best accuracy. In my Sako 85 Varmint .204R the bullets are seated very short of the lands and also the same with my mate's CZ 527 Varmint .204R where we are talking accuracy of about 0.3 MOA and the accuracy I aim for with Varmint Calibres. My favourite Varmint Calibre BTW is my Single Shot Sako S491 22BR which is a deadly long range varminter.
Anyway... enough rambling.
Twist rates in Factory Rifles is what I'm stuck with. I would love to try a .22 Hornet with a slightly faster twist rate like say 1:15 or even 1:14 and the same goes for my .204R which doesn't like 40gr Bullets at all with it's 1:12 Twist Factory Barrel. BTW, the .204R in any I have tested works best with a huge jump to the lands.
Hope I have provided some food for thought that leads to greater accuracy.