This little experiment was to see if seating cast bullets firmly into the rifling (.080") altered velocity and POI. It was intended to define the extreme end of varied seating depth. My normal seating depth leaves the bullets about .060" off the rifling, this depth being required for reliable magazine feed. Test COL was 2.640". Normal is 2.500".
The rifle is an 1899 Savage .30-30 with 24" barrel, 12" twist. Scope is Leupold VX1 2-7, set on 7 for this exercise. Range is 100 metres. Aiming mark is 1.5" square. Load is 32 gns LeveRevolution with 175 gn cast bullet #U321297HP (yes, .32 Special) sized to .312", lube 2500+. Alloy is estimated 11% non-lead, tested 16 BHN.
Barrel had been wiped with a patch treated with Ed's Red and 2500+ lube, following on from an earlier discussion of getting the clean barrel shot to go to group for hunting loads. Prelubing the bore might or might not have worked getting the first shot to go more or less to group.
The bullets used were a little ratty, starting as seconds, then having been collet pulled, reseated and readjusted to get the required rifling engagement. I was not expecting anything much in the way of accuracy.
All shots were chronographed and individual POI recorded.
First fouler (right hand target) was a little high of the main part of the group. Second fouler would have been in the group. The group itself (3.41" left hand target) was spoiled by the first shot going high, but would have been a good group (1.76") without the high shot. This is at 100 metres, not yards.
Velocity (2185) was almost identical to the normally seated loads, and POI similar or a little lower, so I don't need to get excited about seating depth on that account.
A secondary observation is the very good group without the high shot. I take hope from this group that good things might still be ahead for the new 2500+ lube.
There appears to be a relationship between velocity and POI. The high shot was the fast one (2219). Of the seven shots fired including foulers, the three fastest shots were also the three highest on target, and the three slowest were the lowest POI.
The high shot could be interpreted as barrel still seasoning with 2500+ (third shot), but only if the lube was responsible for the extra velocity. Alternately, the extra velocity may have been due to different neck tension or adhesion resulting from all the length adjustments.
I have noticed that Marlin and Winchester .30-30s throw shots up and down with velocity variations (about 4 minutes per 100 fps), though the Savage is normally much less prone to this effect.
Conclusion: COL doesn't seem to affect ballistics for this load, but could be worth following further in pursuit of accuracy. This would be of academic interest only, since this is a hunting rifle and needs to be loaded for field use.
