I also had a box and a half of similar 150gr Hornady Interlocks, that to be honest were of no use to me just sitting in my drawer, so I decided to work up a load in the .30-06 with those. The intent of these would probably just be practice rounds but there is always the potential they could be used on an occasional doe antelope hunt or maybe a couple years when my boys are old enough for some rifle deer. I could just pick a charge and load up a bunch blindly just for practice but since there may be the potential for some hunting with it I figured I’d go through the Optimal Charge Weight (OCW) load work-up process and get a solid accurate load.
I had found a couple pounds of Hodgdon H4831, which is the same powder for the 180gr load and figured that sharing powder between the two loads would be a good idea. After consulting a number of reloading manuals and online resources I settled on a maximum load of 61.5 grains. An Excel spreadsheet helped me perform the calculations to determine the charges for the individual sets and I loaded up the series of bullets.
Once at the range I covered the target board with my paper targets. I created small targets with a simple ¾” black square at the center (in hindsight I could have probably made the square smaller because it still looks pretty good sized at 100 yards with my scope up to full power).
The first three rounds (set 1, 2, and 3) are simply to make sure that the shots show up on the paper and give you one last chance to quickly adjust your scope. So I fired the bullets from set 1, 2, and 3 at the first target. With sets 4 through 10, the OCW method calls for shooting “round robin” style, so I proceeded to shoot one round from each set and each target. I labeled each target to match the set number, so when I was done shooting the first round targets 4 through 10 had one bullet hole on them. I proceeded to shoot the second round, and then wrapped up the third round. When I was done, targets 4 through 10 each had a three shot group on them. I allowed the barrel to cool approximately 2 minutes between each shot since the weather was still relatively cool.
This is the image of the series of targets that I shot:
At home, I measured the center of each group or the point of impact (POI) and the overall group sizes. The POI is the critical information with the OCW method and I was looking for a string where the POI was very close together. My 180gr targets showed a good string where the POI between several targets was within ¼”, but this 150gr load did not show anything that I was satisfied with and I would not consider any consecutive targets as sharing a POI. Here is an image of the Excel spreadsheet where I entered in the data from the targets to determine POI and group size.
Honestly, if group size was the only determining factor I would be perfectly satisfied with anything ranging from 60.1 grains to 61.4 grains as each group was right at or just under MOA (1” at 100 yards). But group size only tells one part of the story and finding a series of charges that share the same POI results in a very forgiving load for the reloader so I decided to press on. Since I got good groupings from 60.1 to 61.4 grains, I decided to make up a series of graduated loads between 60.1 and 61.4gr to be shot at a later date at 200 yards. I’ll perform the same evaluation of POI and group size and hopefully determine an accurate but forgiving load that I can count on in those occasions where I’d feel comfortable using the 150gr bullet instead of the 180gr bullet.
