FN FiveseveN Forums - 55 grain loads

Posted by Rnelson11:

FN FiveseveN Forums - 55 grain loads: "In FiveseveN Pistol

55 grain Sierra Gameking, HS6 powder, CCI small rifle primers, 1x and 2x fired cases.

3.4 grains - Avg 957 - 1001, 914
3.6 grains - Avg 1032 - 1072, 992
3.7 grains - Avg 1062 - 1020, 1022, 1094, 1111
3.8 grains - Avg 1085 - 1103, 1066
3.9 grains - Avg 1090 - 1063, 1139, 1068
4.0 grains - Avg 1114 - 1141, 1134, 1079, 1110, 1099, 1119
4.1 grains - Avg 1157 - 1098, 1216
4.3 grains - Avg 1229 - 1229, 1222, 1247, 1220
4.5 grains - Avg 1314 - 1325, 1342, 1315, 1293, 1299
4.7 grains - Avg 1296 - 1292, 1293, 1320, 1290, 1285
4.9 grains - Avg 1375 - 1323, 1365, 1438

Primers started to crater at 4.3 grains and the shoulders moved about like factory rounds at 4.5 grains.
No flatening of the primers at all (I do use Locktite 609 on all primers for the 5.7x28).
I saw no signs of overpressure. The overall length of the cases increased slightly from 4.0 to 4.9 (.003 Avg) and I also checked the diameter of the case just above the rim and there was no change at all.
The lighter weight charges hit about 6' low but once I reaches 4.3 grains they started to come up closer to factory rounds.

I can not explain what happened at 4.7 grains but I plan to re-test these and go up to 5.5 grains. It is suppose to rain today so it may be next weekend before I can test anymore."