Which weight bullets are you having luck with? I just bought 1 box each of 40, 54, and 60 grain Hornady..
I haven't really shot a lot through this particualr barrel. What I have shot were my standard .223 loads that always shoot well in other 1-12 twist barrels. The 52 gr Speer HP over 26.5 gr of H335 or the 55 gr Hornady SX over 26 gr. My TC barrel will shoot pretty consistant MOA with either load. This is good as the scope was only 4X so with a little tweaking and a better scope it should do better. Just haven't worked with it as I prefer the .22 Hornet TC carbine barrel for the shooting I do with it.
I have shot thousands of .223 rounds through several other 1-12 twist barrels, ARs, M700V and a M70 XTR. The 40 and 45s work ok up to 3600 fps unless they are Hornet bullets. Some of them will spin apart after exiting the barrel at higher velocity than 3200 fps. The 50 and 55 gr SX or Blitz bullets made for up to 3200 fps are superb in the 1-12 barrels. Doubt you'll get any decent accuracy with the 60 gr bullet.
Years ago for bolt guns I found the 55 SX bullet to be the best bullet for critters from squirrels through coyotes, though I have shot a few larger animals successfully with it also. The 26/H335 load (26.5 in milspec chambers) will most often shoot sub MOA all day long. In gas guns the 52 gr Speer gave excellent accuracy and terminal results. I have tried a lot of bullets in the .223s with 1-12 twists and that's what I settled on. Some of the newer BT bullets shoot as well but none are really any improvement for accuracy or terminal ballstics, just newer is all and almost twice the price. For match shooting any of the 52/53 Match bullets will work quite well.
Were I going to get serious with my TC barrel for hunting I would look at the 55 SX/ H335 load for general use. For a "light" squirrel load the Hornady or Sierra 45 gr Hornet bullet with 4227 powder at around 2700 fps (dulpicates the .22 Hornet) would be the ticket. Also, I use Lymans 224415 at 1800 fps in the M70 XTR on ground squirrels and such. Should work as well in the TC Barrel but I just haven't gotten around to trying it.
The newer faster twist barrels in .223 are another story as to what they like.
Your two lighter weight bullets should work just fine. The 60 grain bullet is right on the edge of what a 1 in 12 twist barrel will stabilize. And as the bullet goes down range (i.e. slows down) it will definately become unstable if it isn't right out of the muzzle.
What you might see is the 60 grain bullet shooting accurate up to 50 yards, but then getting very dissappointing (say four inch groups) at 100 yards. 200 yard accuracy will be even more disappointing. The first sign of unstability is inaccuracy, not tumbling.
Maybe you'll still luck out and shoot those 60 grainers just fine. Some combinations of bullet and twist work better than others. Me, I'd stick to a max weight of 55 grains with the 1 in 12 twist.
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