@ 10:00 am (GMT)
Nathan FosterHi Arve, thanks, glad you are enjoying the site.
OK, regarding the 140 grain Accubond, it is a very violent, wide wounding projectile but can suffer at the extremes. When pushed at extremely high velocities and used at close ranges on heavy bodied deer, penetration can be poor and in many instances, excessive weight loss can be the result. On the other hand, as velocities fall below 2400fps, kills can be quite delayed. The 140 grain AB works very well in the .270's out to ordinary hunting ranges on light to mid weight deer.
As for the Barnes TSX, your post is very timely. I had an email from a reader in Alberta who shoots a .270Wby, concerned that I had not properly re-iterated or described how slow killing the Barnes TSX can be throughout the Knowledge base. The reader gave very carefully detailed information based on his own experiences with the TSX describing wounding, ranges etc. These results duplicated my own findings.
Throughout the knowledge base, I have endeavored to describe the strengths and weaknesses of the Barnes TSX but have perhaps been too kind, too subtle when when describing slow killing. The Barnes TSX is favored by a lot of hunters for low meat damage and in some states of the U.S, is one of the only options due to lead bans. However, I do have to re-iterate, this is a slow killing projectile in many instances.
In your .270Wby, the TSX can be made to work well on Elk at ranges where velocity remains above 2600fps and where the front shoulder bones and muscles are encountered as a means to promote fast expansion. But as a general all around projectile for a wide range of body weights at varying ranges with varying points of impact, the Barnes can be a slow killer. Barnes have recently released a line of long range hunting projectiles which are poorly conceived and poorly designed. These are not frangible projectiles and in the absence of high velocity (at long range), can only create a wound channel as wide as the expanded projectile which, in most instances, results in a 13mm / .5" internal wound. This is abysmal performance for long range hunting.
I would like you to start with the 150 grain Partition. Internal wounding will be identical to the results you saw last week (please start recording autopsies with a camera from here on in if possible). The Partition is every bit as violent as the Interlock and continues to produce this performance down to 1800fps, though expansion and wounding will still be very good on heavy deer at 1600fps. The .277 150 grain Partition produces excellent penetration on large bodied deer.
Use the MRP powder (for other readers- this duplicates H4831sc / ADI 2213SC). You might also like to purchase a pack of 150 grain Interlock projectiles as quite often, the two bullet designs will shoot to the same POI, the form and BC's are near identical You can then use the cheaper Interlock for varminting and long range plinking.
The Partition, particularly the projectile in question when utilized in either the Win or Weatherby, is extremely wide wounding (have a look at the 'what is long range hunting to you' post, I put a pic at the bottom of a 150 grain .277 Partition ham wound on a pig). Accuracy of the Partition is dependent on the inherent qualities of the rifle. If the Partition cannot be made to shoot, chances are that the Interlock won't shoot either. And if a rifle cannot shoot the Interlock, there is a big problem as these were very carefully designed to give optimum performance in every conceivable barrel configuration, taking bore tolerances and twist rates into consideration. You should hopefully find that you can get straight into good accuracy seeing as you have already had good results with the Interlock.
Whether to neck size or FL size is dependent on the reamer tolerences and had space tolerances. A generous dimensioned chamber reamer will allow for neck sizing. If the smith opted for generous head spacing, neck sizing will again be optimal. Personally, I prefer to have some slop when head spacing belted magnums and to let the brass flow to fit the chamber, then neck size thereafter for both ease of reloading operations and optimum bullet to bore concentricity.
Seeing as you have a neck die, start neck sizing and monitor chambering over successive reloads. If your hand loads become difficult to chamber, you will need to FL size. This does not necessarily mean you will have to FL size every time. Again, you can monitor this as you go along.
It is hard for me to say whether you have a tight or loose chamber, it will depend on the preferences of the smith. If I had to take a guess, the smith may have felt compelled to utilize tight head space dimensions for the custom build which might in turn require FL sizing with each load. But again, neck size your brass and see how you get on over successive reloads.
As an aside, a lot of smiths have had it drummed into them that tight head spacing is the key to optimum accuracy. This isn't really so and I have tested this using the M700 action, altering the recoil lug thickness and testing accordingly. In the case of your Sako, major variables would have been squaring the bolt face and bolt lugs to the bore along with the receiver threads. A good bore and good bedding, paying attention to critical points of relief are the other critical factors. From here on in, sound, basic hand loads, monitoring bore condition and good shooting technique will be primary factors.