Rifle Loony

The original X got a bad rap because of fouling and because ofhigher than normalpressures, with both problems walking hand in hand it affected accuracy. Thosewho sufferedthe bad luck made a big enough stink over it that Barnes was forced into a redesign.....a good thing, in my opinion.

The resulting groovesperform two functions, first they reduce the bearing surfacewhich reduces the operating pressure, less metal riding on the bore takes lesspressure to push it. With copper being lighter than lead it takes a longer bullet to achieve the same grain weight as a jacketed lead bullet. Theoriginal X had to be long and resulted in too much bearing surface, thegrooves on the TSX make a dramatic reduction in bearing surface.This brings thingsonto sortathe same playing field as normal jacketed bullets regarding pressure and often you'll find that TSX's can be pushed faster than jacketed with the same level of pressure.

Second, the grooves allow a "space" for copper that is displaced by the riflingto "collect" and "roll up" off the bore's surfaceasthe bulletpassesdown the bore. With normal jacketed bullets this same displaced copper is dragged or galled all the way to the base of the bullet and is depositedon the surface of the bore resulting in fouling. A jacketed bullet has more contact with thebore and thus more heat and friction produced, this is why you get fouling in the first place.Thelarger bearing surface of the jacketed bullets allows enoughheat and friction to make the fouling "stick". If you've ever cut aluminum or brasswith an unlubricatedcarbide toothedchopsaw blade you'll understand how soft metal"galls" and sticks to harder metal. TheTSX'sgrooveslessen the heat and friction with lessbearing surface to begin with, and the space in each grooveallow the galling metal to "roll up" before it gets "hot" enough to stick as bad as it would with jacketed bullets.....an accidental side benifit.

Barnes suggests cleaning out fouling from jacketed bullets before shooting TSX's to reap thier accuracy potential. I've found this to be true and can only think that thejacketed fouling defeats the design of the TSX's grooves by forcing them to ride over fouling that is "bigger" than what the TSX would leave.

My experience withthe TSX is that they leave less fouling than any jacketed bullets I've used........

spaniel

I have a Remington Sendero 300WM and shoot the 200gr Accubond and Sierra Match King in it.

Here was my strategy:
1) Determine length of chamber. Seat bullet long, mark all of bullet with black permanent marker. Seat bullet progressively deeper until it will just chamber without engaging the rifling (which makes marks in the marker). This is maximum bullet length. I backed off 5 thousandths I think, from that. Some bullets like more "jump" to the rifling than others. If you are seating with no idea what jump you have, it is hard to make accurate loads except through sheer luck.

2) Conduct a ladder test at 300 yds. Starting with a low load, shoot a series of loads identical except for powder charge at incremental powder charges (I did .2 grains difference I think). Use a very, very steady rest. 100 yds won't work either. You should see a series of "nodes", where slightly higher charges won't change POI much but then it will jump and again stay consistent for several increasing charge shots. Within each node velocity is about the same; you can then test 3-5 shot groups at each charge within the node of desired velocity to pick the most accurate one. Note you'll have to do with with each new bullet type.

3) Play with seating depth to fine-tune accuracy. I did not bother with this since I was at 1/2 MOA after steps 1 and 2.

I love the Accubond. I would recommend it. However, I question the logic of anyone who told you a 180gr partition was only meant for small deer. That bullet is a fine elk bullet. But for bear I'd go with the 200 Accubond.

MinnFinn

I agree with spaniel on this. An Accubond 180 gr for Elk is a fine bullet, as is their Partition. They like some other "bonded" and partition bullets are designed to retain substantial bullet weight with good expansion on heavy hided, thick boned animals like Elk.
Others can speak to which bullet weight for big bears, if that's what you're going after.

Big Guy01

My gun loves the el cheepo Rem coreloks and they work well on Moose I tried partitions and they won't group in my rifle. the two targets are the same components, gun,day but the only difference onehas coreloks and the other partitions.

spaniel

Forgot to mention that I bet the same people who said the 180gr is for small deer are the same people on the "hunting" show I was watching who were recommending the 300WM as the absolute minimum catrtidge for deer!!!

(What do you use for moose? a howitzer?)

SJAdventures

Was this at 100yds?

Big Guy01

yes 100 yds, gun m-70 winchester

statjunk

I've gotten very similar results between Speer 180gr Spitzer Boattail and 180 gr Nosler Partitions. Except that the Speer were all touching.

Tom