So I have a question off the back of that if I may?
I'd worked up some pretty accurate home loads with 165gn Interbond and then subsequently had problems with just neck sizing the cases on reloading. Now I am full length sizing and have a proper press which I seat way more accurately with so how best should I proceed from here do you think?
1) Load up an average charge or RS52 (EG; 43.5gn) with bullets seated a 2.75" (Hornady's recommended COAL for this bullet), 2.76", 2.77" etc etc until I get to 2.8" (SAAMI max) and see which is the most accurate seating depth, then tweak the load?
Or 2) Assume that 2.75" is the best bet and stick with that, and then just work a load up?
Just interested in your thoughts!
Depending on the rifle, cartridge and the bullet I load all the charge development loads to the same length
A minimum of one calibre depth of straight shank or the recommended OAL
This is hard on light for cartridge larger calibres (90gr .270 for example!)
Factory rifles are all throated to take the largest available bullet in factory ammo
In some cartridges this is a very large range and chasing the lands at a lower weight is futile
(.308 for example, 110gr to 180 or 220gr, .243 - 55gr to 105gr)
Powder makers book data shows a range of velocities achieved
N550 | 2,21 | 34.1 | 787 | 2582 | 2,48 | 38.3 | 885 | 2904 |
MV range of 2592 to 2904 using 34.1-38.3gr N550 in 243 with a 100gr bullet
You probably want to be up above 2807fps in order to achieve the 1750ftlbs so loads in the 34.1-36 range are unlikely to be of value
I whizz through these lower charges with single rounds checking for pressure
above 36gr and up to 38.3 I am looking for accuracy nodes
using 0.3/0/4gr increments initially
usually two, one lower likely around the 36.5 mark and one higher near the limit.
ordinarily you can see a clear shrinking in group size at those two nodes.
Once you have decided on a node, I tend to go back and "bracket" that charge weight
Lets say 37.8 is the best group and you were using 0.3gr increments
37.5 and 38.1 either side are discounted
drop down to 0.1 or 0.2gr either side
37.6 and 38.0 or 37.7gr and 37.9gr
If the group improves, great
If not stick with your first "best charge"
Once you have this charge you can tweak the OAL either side of the initial OAL, I tend to go with 0.2mm or roughly 8 thou
Not sure I can accurately and repeatedly measure and reproduce anything smaller than that and I am not entirely sure it matters in factory rifles....
in practice for stalking loads I skip an awful lot of the above
15 rounds
choose the smallest group. anything inside 1" at 100yds is better than most people can replicate in the field
Load it
Shoot it