The 25-284 is also a great round. Although about the same capacity as the '06 case, it virtually always out performs the 25-06. You can read about it on www.accuratereloading.com, where they test various cartridges. Ray Romain has the reamer and will tell you of its merits. Very good performance with no fire forming makes this a very nice round.
You can have the Sendaro 25/06 barrel (26") rechambered to the 25 Gibbs to see if you liked it unless your 25/06 barrel is shot out?
I would go to a 30" barrel if I were you.
The capacity of the 25 Gibbs is 7 to 9 grs More of powder over the 25/06 depending on the brass you use.
For velocity comparison, check the Sierra loading book for the 257 Weatherby and that is the velocity you will be able to get with the Gibbs. Actually when I ran them hot with good actions, I could soundly beat the 257 Weatherby by 100 FPS (or more) in most cases and in my 30 to 34" barrels.
I don't advise going that hot though. Excessive Speed kills accuracy and wears barrels very fast.
I was thinking of rebarreling my 25-06 sendero to 25 gibbs, as a long range varmint gun.Can anyone tell me what the case capacity is,and what kind of velocity to expect with a 28" barrel and 100gr pills.Thanks
Hey I have a Gibbs and am having bad luck with brass and fireforming. My dad built it about 15 years ago and we started with 30-06 put in a .270 die then in the .25 Gibbs die. We had problems with the neck splitting so I bought a box of 25-06 and loaded out to the lands. The primer strike seats the bullet deeper and leaves only a light dent on the primer. Should I try the Unique and filler or different bullets? Anneal the necks? How about the lee crimp die? Am using this gun on a desert sheep hunt but running low on brass and time. Do have 30 rounds loaded for the hunt, 10 practice rounds and 6 more to load. Wish I could get the extra 100 ready though. Very accurate and nice shooting round. Dad killed his 2 biggest mule deer with it. Load is 59.0 H4831 with a Sierra 117 BT. Want to get a load for TSX's , Ballistictips, ACCU-BONDS or Swifts shooting for this gun. Seems like fireforming/wildcat help is hard to come by.Thanks for any help. Gene