Efficiency question about guns....

[Timber338]

You're exactly right 200 fps gain for 21 extra grains is definitely less efficient. Based on your original example of 21 grains increase for the RUM, that works out to 28% increase in powder. For the 300 RUM to be as efficient as your 300 win mag, it would have to have a muzzle velocity of 3217 fps, for an equivalent 28% increase in muzzle energy. And that's just not gonna happen...

I'm with dkhunt14 on this one... the WSM cartridge is about as efficient as they come while still being able to achieve reasonable velocities with the heavy bullets. The 300 WSM makes your win mag look like a waste of powder!

 

[Greyfox]

In the context of a hunting cartridge I tend to agree with views that bring energy into the equation. Being a fan of the 6.5 caliber, there has been quite a few new additions that have shown up over the past few years. Years ago, I began with the 260. Using an optimized bullet, I could generate the 1000 ft/pds of energy I needed at 700 yards. Wanting to get to 1000 yards, moving up to 6.5-284 got me there in a rifle weight/size that I considered feasible. It cost me less than 10grs more powder to get my energy of 1000 Ft/pds in a practically sized rifle which was very acceptable. As I have looked a some of the more recent higher performance 6.5's , in most cases I might get an extra 100-200 yards of range that gives me my 1000 ft/pds, and and a very minor improvement in wind drift/trajectory. Since this improvement isn't material for my specific criteria, at least for now, I feel I'm at a good efficiency with my 6.5-284 and have no motivation to change. I'll use the money on a better RF or scope. IMO

 

[J E Custom]

One other thing, There is a certain efficiency improvement in some cartridges because of the cartridge shape.

The Efficiency is normally in ES and SDs being better/lower. Bench rest shooters believe that a short fat case is better because of better, more consistent powder burn in a short column of powder because of the Flame front .

It is hard to disprove because most of the bench rest cartridges are short and fat. They are also normally small capacity cartridges that burn fast burning powders.

The game we are in "Long distance and terminal energy" requires more of everything, barrel length,
bullet diameter, velocity, energy, High BC bullets, ETC. so powder efficiency is not a prime concern.

An Efficient cartridge is one that fills a certain need for distance, game, trajectory, energy at POI
and resistance to outside interferences(Like wind) the farther out we go the bigger the bullet, the more powder, the longer the barrel, the larger the case needs to be.

I own a 7 WSM because I had heard how efficient the Cartridge was. I also own a 7mm rem mag. both rifles have the same barrel length so I was interested in seeing what the WSM would do compared to the 7mm rem mag. I could never reach the advertised velocity of the WSM with reloads and the recommended powders available.

So I unloaded one of the factory rounds that would match the velocity of the 7mm RM with the same bullet weight and found 71 Grains of powder in the WSM (Way more than the powder weight possible in the 7mm RM with the same bullet weight. so Is the WSMs more efficient ? in my opinion NO. It does operate at a higher pressure than the 7mm rem mag though. But It is nice to have the same performance in a short action rifle.

Just more conversation about Efficiency.

J E CUSTOM

 

[MontanaRifleman]

So.... Let's ay that the Ultra was 200 fps faster than my 300 wm. Wouldn't it still be less efficient? More? What??
The guy (please forgive me for not remembering your name) choosing his 7 mm over a 30 cal. makes a good point and understands the debate.

Thanks for ALL your responses.

Some very good replies here. That said, a smaller caliber is NEVER more efficient than a larger caliber. A smaller cartridge in the same caliber is ALWAYS more efficient (powder vs velocity/energy) than a larger. Shape of the case has little to do with it. A 300 WM will out perform a 300 WSM because the WM has more case capacity. A 7 WSM and 7 mag are going to be very close with the 7 RM usually on top. A 300 WSM/WM is more efficient than a 300 RUM. A 30-06 is more efficient than a 300 WSM or WM. And a 308 Win is more efficient than a 30-06. BTW, a 300 RUM is a long 300 WSM.

I have loaded for the 7mm RM, 300 WSM and 300 RUM. In the 7 mag, the best velocity I got with a 160 gr bullet was 3150 out of a 24" barrel using RL17. In the 300 WSM, I was able to push a 180 gr bullet 3200 plus out of a 24 3/8ths barrel using 5 less grains of RL17 than the 7 Mag.

In the 300 RUM I could push the the 230 Hybrid to 3150 or so with about 96 gr or so of RL33 out of a 27" barrel. That is 300 fps faster faster than your 300 WM but there is an efficiency cost.

Bottom line is, if you want performance, you're gonna have to pay for it. No pian, no gain. Question is, how much performance do you want and more importantly, how much are you willing to pay for it.

Efficiency IS relative but efficiency is not my priority in LR. If I was a short to mid range hunter in the Eastern/Southern states, my go to rifle would be a 308 Win hands down. But I am a guy in Montana where there are a lot of long shots and very few calm days.

Cheers

 

[MontanaRifleman]

The 300 WSM makes your win mag look like a waste of powder!

No flame intended, but hafta disagree with that.

 

[FearNoWind]

I agree with you. But some guys have the bucks and can't resist the temptation to push the load for another couple of feet per second. A lot of the guys I shoot with spend countless hours and lots of money trying to get another 25 - 50 fps out of their load. They strive for those increases incrementally until they get to the inevitable limit of perhaps a 100 fps increase. But their targets don't look any better than mine and they suffer from insomnia. Don't make sense to me either.

 

[Timber338]

No flame intended, but hafta disagree with that.

haha. no worries. I know I was kind of stretching with that just getting my point across. I own a 300 win mag and love it.