I am new to the LRH site and I've seen a lot of talk about 300 ultras, but I can't find anybody else shooting a .30-378 Mark V. I've had this rifle for about 6 months and finally settled on a load for it after a lot of trial and error, from trying 5 different powders and bullet combos. There really isn't a lot of load data out there for a true long range load in this caliber.
My load is using Reloader-25 to push a Sierra MK 240 gr. at 3050 fps. This is very close to the pressure limit and I went as high as 3160 while "pressure testing" the recipe. The rifle is a Weatherby Mark V standard with the 28 inch barrel, plus the brake. I do not use the brake, and although it was very effective in reducing recoil, the inherrent loss of accuracy and the muzzle blast are not required (in my opinion) for what is still considered a "standard size" rifle. I know if I wanted to use the brake while out hunting with my buddies, I would soon find myself with much fewer friends. The scope is a Leupold VX-II 6-18x40mm with the long range varmint reticle. This load has proven to be slightly over a 0.6 MOA out past 1600 yards. I am compensating with 38 MOA adjustment to get out there.
I could find very little data for using RL-25 in this caliber. I think this powder shows a lot of improved performance in this "oversized" magnum cartridge.
Anyone else have any opinions on this caliber or shoot it regularly? I look forward to your replies!
Travis Kamps
(406) 580-9700
[email protected]
You are doing well in the pioneer world of wildcats.
Simple physics as amount of powder vs bullet weight and pressure . The Mark V can take the most pressure all of the actions , 308 calibers are that a 308 to a 3006 to a 300 win mag is just amount of powder.
The reloading manuals are terrible for weatherby . Its start low and work up .
The 100% case capacity and max pressure intersect that's your load check accuracy .
Ball Powder you can pack more in but not as constant burning. VithVo powder is great stuff .
Try the N570 instead of RL 25 it will be more accurate and faster.
The next thing to watch its tempature and altitude it affects the pressure huge huge huge.
Accuracy is 2 concerns targets or hunting . Bullet type and speed doesn't matter to targets as much as hunting scenarios. Bergers work and Nosler Bal. tip or Barnes those 3 like speed vs sierra that doesn't like speed .
You are on the right track , Like like free bore and you will read barrel burner statements but if you can shoot 10,000 rds of hot weatherby a year you like pain .
50 bmg is terrible trajectory but if you know the distance and calulations or time its an amazing round as 308 . But in hunting etc or time you don't know the distance or cal or time you have to be flat and fast.
After 550 yds its a step curve for everyone but 200 in drop vs 500 in drop at 1000 is a huge guess. Wind ?
Lija bbl are good and they know weatherby well. For hunting #1 for completion Bartilen .
Trick is to go buy a $500 Mark V at a gun show 300 weathery action not a small action trashed out gun the better . You only need the metal . Sent it to Dan Lijlas gunsmiths and put a bbl and cut the bot groove and face and you have a $5000 Weatherby custom that shoots sub MOA .
I have wildcatted and weatherby since 1972 and like them but I do owe a 308 as it has its fun place but limited.
Build a 6.5 x 300 weatherby on a old Mark V with a Bartilen bbl free bore it you will love it .
Muzzle Brakes use them all the time never take them off the bigger the holes on the sides the better and big. many, BBl length ? need to be over 28 in for sure but not over 31 in .
Just my thoughts , good luck
