Somewhere, I read that breaking the seal around the bullet on the CMPicon's Greek HXP would improve accuracy. I decided to test this theory. All rounds came out of the same spam can of HXP-69 which has proven to be very accurate ammo. All rounds were first weighed to eliminate any highs and lows and then spun to eliminate any round more than .006 inches out of round at the bullet. 54 rounds produced 40 matched rounds and 14 rejects. The rejects were set aside and not used in the test. I then took twenty of the matched rounds and ran them up into a Bonanza bench rest bullet seating die set to push the bullets another .010 inches into the case. On each and every round you could hear the sealant make a distinct cracking sound as the sealant was broken. I then retested these rounds for runout and if anything, the Bonanza die made them even straighter.

The results were not what I expected. The rounds with the bullet sealant broken were terrible. The undisturbed rounds still produced the same accuracy that this lot of HXP-69 has been good for in the past. Now, this test is with one lot of HXP in one M1icon Garand. I am not saying that anything should be etched in stone here. But I am suggesting that before you set up your bullet seating die and break the sealant on 500 rounds of HXP, you might want to do a little small lot testing.

All rounds were weighed and spun for consistancy:



Accuracy with the undisturbed rounds was what I have come to expect from this lot of HXP. Half of these rounds were fired single fire using a sled and half were fired semiautomatically rapid fire:



These are the broken sealant rounds fired the same way, half single fire and half rapid:



Further testing at 200 yards slow fire prone on a NRA SR target showed that while the undisturbed rounds would hold the ten ring when I did my part, the broken sealant rounds would not stay in the black no matter how careful I was.
Information
Warning: This is a relatively older thread
This discussion is older than 360 days. Some information contained in it may no longer be current.