I picked up a box of the cavity back 120 mkz bullets a few weeks ago to do some testing with before early bear season starts here in NY. so far I'm very impressed with the results I have gotten shooting into ballistics gel. I worked up a load with 8208 xbr that gives me about a 2 inch group at 200 yards which is plenty good for hunting in upstate NY. here are my velocity results:
16" YHM melonite coated barrel
120 mkz
S&B brass (once fired)
wolf primers
oal: 2.295
temp: 80 degrees
8208 xbr powder:
29 : avg 2450 fps
29.5 : avg 2483 fps
30 : avg 2534 fps
30 grains ended up being the most accurate so this is the load i used for the gel tests. on the hodgdon website they list 30 grains View attachment 49413 as the highest load for 115 grain bullets loaded at mag length. I had slightly flattened primers, but no swipes or blown primers. now to move on to the ballistics gel testing. I started at 35 yards to test at max velocity.
35 yards:
shot 1: I put a empty 1 pound propane tank and a 1 inch thick pine board in front of the gel to see the bullets barrier performance. the bullet did not expand and went through both barriers, 24 inches of gel and got caught in a gallon jug of water I put in the back. the bullet did tumble right at the 12 inch mark leaving a large wound channel. on inspection you could see the tip of the bullet was essentially covered in metal preventing it from opening.
shot 2 : I removed the barriers and the bullet performed perfectly penetrating 17 inches. the bullet fully expanded to .78 inches leaving a 5" wide permanent cavity from about 1-8 inches. this is widest wound tract I have gotten from any monolithic 6.8 bullets I have tested.
100 yards:
performed perfect again expanded to .75 inch and penetrated 19 inches. the wound channel was 4.5 inches wide.
200 yards:
my first shot veered out of the gel around the 14 inch mark but my 2nd shot stayed in the gel. again perfect opening up to .70 of an inch. penetration was 17 inches with a 3 inch wide wound channel.
300 yards:
after doing some sighting in I only had 3 bullets left. the first shot hit low striking the the 2×6 board the gel was sitting on. this bullet was recovered after going through about 6 inches of the board and was expanded to to .64". the 2nd and 3rd shot both hit the gel on the right side about an inch into the gel. both shots completely blew off the side of the gel, but only one made it into the 2nd gel block stopping at the 17 inch mark. this bullet expanded to .65 of an inch, which is very nice for 300 yards. I would like to retest at this distance and try to hit the gel more in the center to see if it gets the same penetration
16" YHM melonite coated barrel
120 mkz
S&B brass (once fired)
wolf primers
oal: 2.295
temp: 80 degrees
8208 xbr powder:
29 : avg 2450 fps
29.5 : avg 2483 fps
30 : avg 2534 fps
30 grains ended up being the most accurate so this is the load i used for the gel tests. on the hodgdon website they list 30 grains View attachment 49413 as the highest load for 115 grain bullets loaded at mag length. I had slightly flattened primers, but no swipes or blown primers. now to move on to the ballistics gel testing. I started at 35 yards to test at max velocity.
35 yards:
shot 1: I put a empty 1 pound propane tank and a 1 inch thick pine board in front of the gel to see the bullets barrier performance. the bullet did not expand and went through both barriers, 24 inches of gel and got caught in a gallon jug of water I put in the back. the bullet did tumble right at the 12 inch mark leaving a large wound channel. on inspection you could see the tip of the bullet was essentially covered in metal preventing it from opening.
shot 2 : I removed the barriers and the bullet performed perfectly penetrating 17 inches. the bullet fully expanded to .78 inches leaving a 5" wide permanent cavity from about 1-8 inches. this is widest wound tract I have gotten from any monolithic 6.8 bullets I have tested.
100 yards:
performed perfect again expanded to .75 inch and penetrated 19 inches. the wound channel was 4.5 inches wide.
200 yards:
my first shot veered out of the gel around the 14 inch mark but my 2nd shot stayed in the gel. again perfect opening up to .70 of an inch. penetration was 17 inches with a 3 inch wide wound channel.
300 yards:
after doing some sighting in I only had 3 bullets left. the first shot hit low striking the the 2×6 board the gel was sitting on. this bullet was recovered after going through about 6 inches of the board and was expanded to to .64". the 2nd and 3rd shot both hit the gel on the right side about an inch into the gel. both shots completely blew off the side of the gel, but only one made it into the 2nd gel block stopping at the 17 inch mark. this bullet expanded to .65 of an inch, which is very nice for 300 yards. I would like to retest at this distance and try to hit the gel more in the center to see if it gets the same penetration
