Which of these would be the best in a contender pistol with a 10" or 12" barrel?

More horsepower in the Bullbery improved.I can not speak about accuracy but bullbery stuff is pretty darn good!!!

I agree on Bullberry. Super quality, super accurate and highly recommended! I have a 44 mag barrel from them and it is a one-holer, even with factory ammo.

After some more research, I am starting to lean towards the 6.5 JDJ.

You never mentioned the most important thing . . .

Whatcha gonna do with it after you put it together.

IF I was just gonna punch paper, it would be 6.5 TCU for sure due to the economy of powder use.

Hunt + paper plus some varmints in between . . .

Then 6.5 JDJ is where ya wanta be.

Glen Fryxell and likely many more we have never heard of have stopped some western mulies with the TCU though. Some of Glen's writings might still be here on this site.

Do some google searches on WV Hitman and Glen Fryxell with 6.5 included in the search.

Handgun Hunter web site likely has some info too!

The 6.5 TCU is a neat little round. The 6.5 JDJ is a workhorse in that caliber range.

Well from good advice and research, I have concluded that I need a 6.5 TCU in a 10" barrel to carry while bird hunting to dispose of coyotes and bobcats that pop up. Then I need to get a 6.5 JDJ with a 14" barrel for deer and such. And since doing all of this research, I have stumbled onto a decent priced 375 JDJ that is ported with a scope that would come in handy on a hog hunt. I hope that my pocket book can handle all of these new discoveries.

The .375 JDJ is an entirely new level. You will get spoiled with that one. The cases are very easy to make and that cartridge has the accuracy and ability to take any creature on God's green earth.

Fryxell used 10" TCU with Nosler 120 grain BTs for deer.

The 120 BT is the 6.5 Bullet of choice.

10" 221 or 222 would smite the occasional coyote or bobcat quite well and quite dead.

IF you are not hung up completely on the 6.5, the 7X30 would work for what you want, including deer. SD Handgunner would the source of anecdotal information on this one.

Of course one could pour a nice powder charge under a 85 grainer in the TCU and it could rattle along til the hit the TC throat, it may make a coyote retire