Originally Posted By: JCLI had a failure to hold together on a bull elk hit in the shoulder at 275 yards with a 300 RUM and a 180 gr TSX bullet. The bullet broke into pieces leaving a huge hole in the skin, it did shatter the shoulder but failed to penetrate into the body cavity. I no longer use the TSX due to this and another bullet I recovered from an elk shot from the 300 RUM using the 180 TSX that looked like an FMJ. All the petals were blown off on entrance and the wound channel besides the outside skin damage looked like an FMJ had passed through. I was not impressed. This is from a guy who swore by the X bullet for 10 years and switched to the TSX when they quite making the original X.
The only difference between the TSX and the X bullet are the rings around the bullet to reduce pressures,and because of them the bullet length ended up being a little longer giving you a slightly higher SD and BC. I think that if you had put a Partition in the same spot on that bull you would have had less penetration. I've done some very extensive testing on the TSX's into a very hard medium (water filled milk jugs) with cartridges ranging from the 257 Roberts(115gr@2800fps@20yds) to the 7RUM(140gr@3600fps@20yds) and the worse case scenario I ever had was with the 7RUM where the bullet lost its petals in the 6th jug, but the bullet still penetrated all the way up to the 12th jug. The remaining bullet was petal-less, but mushroomed. This happened only once during my testing whereas I shot 14 times @ above conditions with that particular round.
That being said, I believe that the biggest problem is that ALL of the premium bullets are subject to failure in the hyper-velocity cartridges (RUM's, STW's, and the bigger Weatherby's)when encountering heavy bone, especially the joint in the shoulder. I am surprised to hear that the whole bullet stopped in the shoulder though as usually the base will still penetrate. What was your velocity on your 300RUM?
I haven't had the chance to start testing the Hornady GMX yet but they are not made of pure copper, rather, gilding metal copper alloy usually found in jackets. Maybe they will be able to hold together better in the hyper-velocity cartidges?
Personally for this years elk hunt I've settled on the 210gr tipped TSX for my 338-06...
15 bullet tests into milk jugs averaged 11jugs of penetration with picture perfect mushrooms
when shot at 20 yds at 2750fps. I can get more velocity out of the round, but need to keep it at 2750
to match up to my Shepherd scopes reticles.
Hope you have better luck with your RUM,
johnny