How different are these two bullets in a given weight? I'm guessing (but haven't any long range experience with the HP) that the FMJ is going to be more accurate at long range? Anybody care to enlighten me?
The Sierra match king bullet (used in Federal GMM) has a hollow-tip, which is a by product of manufacturing and not intended for expansion at all. This hollow tip effects accuracy NOT AT ALL. The US Armed forces switched to the Sierra Matchking 175gr with the M118LR ammo, this was a switch from the 173 BTFMJ in the M118. But, like I said, it was not because it had a hollow tip (we are not allowed to use exanding bullets in combat anyway) its because its a superior bullet. Now, Lapua exceptional bullets also, but theirs are all FMJ... again, its all in the quality and design of the bullet.
Some people have argues the hollowtip has aerodynamic advantages, but I would argue more that is does NOT have aerodynamic DISadvantages.
When comparing bullets, check out the ballistic coeffecient (BC). The higher the number, the better. This gives you a quick comparison number for figuring long range ballistics. So if two bullets were fired at the same muzzle velocity, the one with the higher BC will retain energy better and have better long range ballistics then the other.
I read up on some documents once that said when the .300 win mag was being evaluated (I think it was navy special warfare) they said that without the hollowpoint, rounds were hitting targets sideways at 800 m...do you think that could be true?
If the round they were using was not stabalizing that's exactly what you would expet them to do. I have no idea what round they were using during the test, but if I tried to shoot Sierra 220 MKs out of my 12 twist 308, that is the result I would expect.
if it failed to stabilize then how would it hit the target 800m out?
i have played around with some .223s in 69 and 77gr BTHPs with my Varminter (24" barrel, 1:9 twist)
77 gr BTHP were able to do ok at 100y and sometimes at 200y but even then had problems (not match grade accuracy though) while 69 gr BTHP shot flawlessly
byond 300y a 77 gr BTHP wouldnt hit a parked car while the 69 gr BTHP was doing just fine out much further
i have played around w/ Federal FMJ-BT rounds but not match grade ones just their surplus and thier budget rounds American Eagle brand they do just as well but thats more of a gun preference than it is a quality of round differnece
im sure that some guns the BTHP will do better while some the FMJ BT will do better seems that the BTHP has a higher bc so at longer range its probably better
I would agree that if the bullet was going through the target sideways, it was not stabilized. It has nothing to do with a hollowtip or not. Lapua, who makes bullets every bit as good as sierra, has no such hollowtips on any of their bullets. The M118 has a 173gr FMJBT. The list goes on. The hollowtip of the sierra match king bullets is a bi-product of manufacturing, it is not done for aerodynamic reasons, or expansion reasons. Sierra wraps the jacket around the lead core from the base to the tip, this is why there is the tiny hollow tip.