Long Time Long Ranger
Well-Known Member
Weatherby cartridges are some of the most accurate cartridges ever designed. Numerous long range world records have been held by them and matches won with them. I have built wby's for 35 years and they will shoot with anything out there. The 340 will shoot just as accurate as the ultramag. It gets about a 100 fps less velocity with between 10-15 grains less powder. Like I said I think the last model 70 I did which was a 375 H&H to 338-300 ultramag Didn't require a lot of work to make it feed the ultramag case. If that is true then I would go with the 338-300 ultramag for the little extra. You would not have to load it hot to get the 340 velocities where you would be loading the 340 hot to get it up toward the ultramag. Brass would be a little cheaper with the 340 since you can use the 375 H&H and neck them down then trim to length. I have one 340 that I built back in the 70's and it still shoots great. Matter of fact I am sitting here looking at a load with the sierra 215 gameking at 3287 fps that has 1 3/8" at 400 yards written by it.
I would try to get with one of the guys on here who has worked with the model 70 action a lot converting it to the ultramag case and see what kind of feeding problems you will have. If it will feed well that is where I would go. If not I know the 340 would feed perfectly since the standard mag case is what your action was designed for. The 340 will kill any elk at any range the ultramag will and the elk would never know the difference so you would not be limiting yourself. I have several big 338's that I shoot all the time. My 338-378's will shoot on average about 250 fps faster than the 338-300 ultramag and about 150 fps faster than my 338 Lapuas using 200-225 grain bullets. Then comes my 340 about a 100 fps slower than the ultramag. I have killed elk with all of them and from the 340 to the 338-378 they all do a good job. The 338-378 gets most of the work because of the extra velocity giving less time of flight and less wind drift. My accuracy load in it shoots the 225 accubond at 3475 fps with 124 grains of H-870. That varies depending on the batch of 870 which can be up to 5 grains batch to batch. I already gave you the accuracy load in the 340. I hope some of this makes some since but all in all you can't make a bad choice with one of these.
I would try to get with one of the guys on here who has worked with the model 70 action a lot converting it to the ultramag case and see what kind of feeding problems you will have. If it will feed well that is where I would go. If not I know the 340 would feed perfectly since the standard mag case is what your action was designed for. The 340 will kill any elk at any range the ultramag will and the elk would never know the difference so you would not be limiting yourself. I have several big 338's that I shoot all the time. My 338-378's will shoot on average about 250 fps faster than the 338-300 ultramag and about 150 fps faster than my 338 Lapuas using 200-225 grain bullets. Then comes my 340 about a 100 fps slower than the ultramag. I have killed elk with all of them and from the 340 to the 338-378 they all do a good job. The 338-378 gets most of the work because of the extra velocity giving less time of flight and less wind drift. My accuracy load in it shoots the 225 accubond at 3475 fps with 124 grains of H-870. That varies depending on the batch of 870 which can be up to 5 grains batch to batch. I already gave you the accuracy load in the 340. I hope some of this makes some since but all in all you can't make a bad choice with one of these.
