I have a 7mm Chilaen Mauser that I took it to the range today and did some group shooting. I found that it does not like anything lighter than 154 grain bullets.
I had a few different bullet weights 120 gr., 129 gr., 139 gr., 140 gr., 145 gr., 154 gr., 162 gr., and 175 gr. The bullets that were lighter than 154 grains looked like a shotgun blast. I could get nothing that even resembled a group. At first I thought that it was me, then I thought it was the sights. Nope, looked at the crown nope, looked fine.
I had a bunch of 154 and 162 grained handloads so I stuffed in a few 162 gained handloads and Bingo, the group shunk down to 1½" for the 162 gr. SPBT Hornadays. Thought I would try the 154 gr. SP Hornadays and got a 2" group. Next I went to the 145 Winchesters Factory loads and 140 grained handloads. Again a shotgun blast the best I could get was 7.2" with the 140 grained handloads the 145 grained Winchester factory loads measured 7.58". I tried the 175 grained Winchester factory loads and the group shrank to 1.6". I then tried a group with 129 grained Speer SPBT and the group blewup to almost 9". Back to the 154 grained handloads and again 1.93". I thought I would see how the lightest bullet I had would fly and got a group that was 9.33" Next went to the 162 grained handloads and the group measured 1.52" I know that the original loads for this rifle featured a 175 grain bullet at about 2300 fps. I'm pushing the 162 grain at 2570 fsp. I was supprised when I could not get the lighter bullets to group. I guess it is the twist rate. I have never had this happen before, it has always been the heavier bullets that would not group do to slow twist of the barrrels.
Has anyone else had this expirence?
Kirkned
