338 Rum or 300 Prc build?

I am starting to look at building a new rifle next year, except I plan to do the build instead of finding a Smith, I have been debating on the Grayboe line versus using McMillan or Manners. I have a McMillan, on a Custom 28N, but wanted to go different. The price seems better than McMillan and Manners.
 
I am starting to look at building a new rifle next year, except I plan to do the build instead of finding a Smith, I have been debating on the Grayboe line versus using McMillan or Manners. I have a McMillan, on a Custom 28N, but wanted to go different. The price seems better than McMillan and Manners.
Don't overlook AG composites or even Iota. As for the caliber dilemma, 338 all day. Your PRC will net you nothing you don't already have. A 338 however... let's just say you won't need a viagra after pulling the trigger 😁 and I went with the RUMso I could have the option of factory ammo if I needed it. But since you already have 300 RUM brass, the EDGE might be a wiser choice. Plus 300 RUM brass seems easier to find and just needs to be necked up
 
Well I can tell you from experience that the 338 Rum and 338 Edge are very close .
That being said your choices given were a 300 prc and the 338 Rum .

Build a 338 Rum 28" proof or Carbon in a 1/9 twist, T-3 Termanator brake and a McMillan Edge fill stock . Light weight Scope and push the 300 gr bergers .
I have had excellent luck with H-1000 !
You should expect velocity about 2850 to 2900 ft.per.sec.
This should be a fantastic Elk , long range Mule deer combo ! If your shooting ability is up to par !
View attachment 213062


Rum Man
Good choice on the powder!
 
Why go 300prc when it's just a few fps faster than a properly throated 300wm that you already have? Factory ammo? I can understand that. The 338 rum is a beast. My 338 rum pushes 300 bergers @ 2820 very accurately. It's throated long and is using a 4" mag box.
You didn't clarify your application/needs/desires. Maybe, just want 338RUM?? Go for it. If there are specific application parameters, then consider those. You don't want a barrel burner like your 300RUM?? 338RUM is just that on steriods......much over bore, barrel burning excess powder for the extra umph delivered. Unless a specific need for it's characteristics, I wouldn't go there. See the comparsion, features of the 300PRC versus other popular 300 cartridges, including your 300WM, following. There are many reasons to go 300PRC over 300WM. 300WM is still, and will remain, a venerable, serviceable, great performing old warrior. Great factory field ammo availability is a feature not available for the newer 300PRC yet.

This has been discussed before on LRH 300PRC vs 300WM. There are numerous advantages of the 300PRC ; numerous limitations, disadvantages of the venerable old warrior 300WM designed with technology, knowledge of 60yrs ago. 300WM is a fine round, but today there are better.....depending upon one's application, needs, and preferences. Here is a comparison of the two.
300PRC vs 300 Win Mag.jpg

300PRC left; 300WM right
300 Winchester Magnum vs. Hornady .300 PRC

300WM biggest disadvantage is a quite short 0.72-inch "head height," which is the distance between the front of the case mouth and the cartridge's SAAMI maximum overall length. Ammo factories must load to this standardized maximum, which prevents factory ammo from being loaded with long, super-sleek bullets with the very fine, gradual entry that so benefits extreme-range aerodynamics.

In contrast, the .300 PRC is engineered with the latest cutting-edge cartridge design principles, and features a 1.12-inch head height, enabling the use of very long, low-drag projectiles without intruding inside the case. (You'll find this is a common thread throughout most of the following comparisons.)

The SAMMI throat of the 300WM is 0.315.....throwing a bowling ball down a hallway.....versus 300PRCat 0.3088......better bullet presentation to the rifling. 300WM is belted making headspacing less precise. 300PRC is a shoulder headspace datum line.




300PRC vs 300 RUM.jpg
Hornady .300 PRC (left) and .300 RUM

.300 Remington Ultra Mag vs. Hornady .300 PRC
This beast provides more initial velocity than any of the previous cartridges discussed, and has proven to be an outstanding elk cartridge. However, it's a bit too much of a good thing. Barrel life is short, and being aggressively overbore, the RUM can be finicky about accuracy.

Plus, it kicks like a demoniac mule, and requires a full-magnum-length action even though it has a short head height. This last fact makes it incompatible with really long-nosed, fine-entry high-BC bullets. Why not just shoot a slightly slower cartridge that pushes heavy, sleek bullets optimized for long range, and which provides less recoil and more performance way out there?
 
You didn't clarify your application/needs/desires. Maybe, just want 338RUM?? Go for it. If there are specific application parameters, then consider those. You don't want a barrel burner like your 300RUM?? 338RUM is just that on steriods......much over bore, barrel burning excess powder for the extra umph delivered. Unless a specific need for it's characteristics, I wouldn't go there. See the comparsion, features of the 300PRC versus other popular 300 cartridges, including your 300WM, following. There are many reasons to go 300PRC over 300WM. 300WM is still, and will remain, a venerable, serviceable, great performing old warrior. Great factory field ammo availability is a feature not available for the newer 300PRC yet.

This has been discussed before on LRH 300PRC vs 300WM. There are numerous advantages of the 300PRC ; numerous limitations, disadvantages of the venerable old warrior 300WM designed with technology, knowledge of 60yrs ago. 300WM is a fine round, but today there are better.....depending upon one's application, needs, and preferences. Here is a comparison of the two.View attachment 213493
300PRC left; 300WM right
300 Winchester Magnum vs. Hornady .300 PRC

300WM biggest disadvantage is a quite short 0.72-inch "head height," which is the distance between the front of the case mouth and the cartridge's SAAMI maximum overall length. Ammo factories must load to this standardized maximum, which prevents factory ammo from being loaded with long, super-sleek bullets with the very fine, gradual entry that so benefits extreme-range aerodynamics.

In contrast, the .300 PRC is engineered with the latest cutting-edge cartridge design principles, and features a 1.12-inch head height, enabling the use of very long, low-drag projectiles without intruding inside the case. (You'll find this is a common thread throughout most of the following comparisons.)

The SAMMI throat of the 300WM is 0.315.....throwing a bowling ball down a hallway.....versus 300PRCat 0.3088......better bullet presentation to the rifling. 300WM is belted making headspacing less precise. 300PRC is a shoulder headspace datum line.




View attachment 213494Hornady .300 PRC (left) and .300 RUM

.300 Remington Ultra Mag vs. Hornady .300 PRC
This beast provides more initial velocity than any of the previous cartridges discussed, and has proven to be an outstanding elk cartridge. However, it's a bit too much of a good thing. Barrel life is short, and being aggressively overbore, the RUM can be finicky about accuracy.

Plus, it kicks like a demoniac mule, and requires a full-magnum-length action even though it has a short head height. This last fact makes it incompatible with really long-nosed, fine-entry high-BC bullets. Why not just shoot a slightly slower cartridge that pushes heavy, sleek bullets optimized for long range, and which provides less recoil and more performance way out there?
Do you know that the 338 rum is smaller case than a 300rum? Did you know that a 338 rum has about 12% more powder than a 300prc, but in a 10% larger bore? So I'm pretty certain a 338 rum barrel will last about as long as a 300prc. The 300wm with a custom reamer that has the same throat specs as a. 300prc, will be within 30-50fps of one another loaded to the same pressures. There have been several test done with 30 nosler, 300prc and 300wm, all loaded to same pressure there's 75fps between the three with the same bullet and chamber specs.
 
If it was me I'd go for the 338 RUM. If you have a 300 and smaller calibers sounds like a 338 would fill out your entourage. As far as recoil goes you can put a break on it and knock the kick down to 270 levels or less. I have a MBM lil beast on a factory sporter barrel and it kicks like a 243. If you don't like the need for ear protection you can always go suppressed. But as far as long range killing power and just general fun the 338 RUM is awesome. But I'm biased
 

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