Home Forums Hunting & Shooting Ask The Gunwriters Cartridge efficiency

Haven’t posted on here in a while so here’s my question for Mule Deer and everyone else who wants to chime in.

I have a 15” Encore handgun barrel in 308 Win. that I’m having trouble finding the right load it likes. I hope to take it out west in a couple of years and harvest an Elk with it. Thinking of having it re-bored to either 338Federal or 358 Winchester. Which would be more efficient? In the 15” barrel. 180-210 gr. in the 338 Fed., 200-225 gr. in the 358 Win. I would probably limit my shots to 250yds. maybe more under the right conditions. I still have a couple of more loads to try in the 308, but I thought I would throw that out there to see what kind of info I could glean from y’all. By the way I’ve been hunting with handguns since 1979.

All the best,

You need to define "efficiency" for starters

Have you had success with that gun with other barrels? Maybe you have a crummy barrel?

I've never used the 338fed and 358win in my life but they're probably choice. I've used my 16"+ scout rifle for elk bear. I doubt there's much difference between that and your 15" single shot. An 180gr cup core works well with enough weight and holds up well at those speeds.

That’s what I’m thinking, maybe a bad barrel.

MuskegMan,
By efficiency I guess I’m asking per grain of powder which one will give the best velocity in the short 15” barrel with the given bullet weight for the caliber.
I know I’m probably opening a can of worms….

Thanks

...... starting with the cost/benefits ratio.

Yep, I've opened a can of worms.... "cost/benefits ratio" you sound like the bean counters we had when I was working, retired now.
I'll probably go with the 358 Win. I have scads of 35 cal. bullets and 308 brass.

Oh well.

I could be wrong, but it's my understanding that if two cartridges are operating at the same pressure, the bore of greater diameter will be faster, because the pressure has a larger surface area to push on. I would assume the .338 fed and. 358 win would be pretty close as far as amount of powder it takes to get to like pressures.

Yes, but on the other hand, how do the the applicable bullets compare regarding SD and BC?

I like the 358 idea. You could shoot pistol and rifle bullets out of it.

Sorta depends on what the problem is with the current barrel. Do you have other barrels that shoot well on that same frame? If it's an issue with locking lugs, etc then reboring won't fix it. The other thing is .. is it the gun or is it you? I finally got around to shooting my Contender with .30-30 and .44 mag barrels I'd had NIB for a decade or so and found that though the Ruger Bisley .454 has "bigger" recoil, the TC flat hurts my shootin' hand in ways the Ruger does not. Grip shape, fit, material, etc. Reboring won't help if the problem is you, not the gun.

All that said, I'd probably look at .338 Federal and load it with 210 grain partitions for elk. Overall the .358 is more flexible, but .. maybe that flexibility isn't useful. Would like to have one to launch 140 grain XTPs at warp speed into ground squirrels but .. is it useful or merely entertaining?

Per OP "I would probably limit my shots to 250yds. "

IMO, BC means nothing here. But, probably so does efficiency.

👍

I’ve had this frame since 1995, trigger work right after I purchased it. I have had all manners of barrels on this frame and all shot good. Some better than other calibers, but all had acceptable accuracy. All were either factory ( Rochester made) or custom. This particular barrel is a Springfield, Mass. made barrel, I picked it up NIB and got a great deal on it. It has a Holland muzzle break and it’s extremely effective along with good optics.
I have also given it the JB Bore paste treatment, no change in accuracy. Maybe I should go ahead and replace the locking lugs, if that’s the issue it will be a cheap fix. Just never had one give me fits like this one has.

I'm no bean counter but any means. I have a 308 here that I was considering doing the very same thing as you, making it into a 358W. I like the 35cals and have owned three or four 358Ws over the years, but also, in my older, more practical years, fully realize that a good 308 that handles heavier bullets well will give me similar results.

I also know what gun-looneyism does to a practical train of thought.

Cartridge efficiency would be calculated by expansion ratio (case powder column capacity plus bore volume divided by case powder column capacity all in grains of water). The longer the barrel means higher bore volume and greater exp ratio. Small bores with big case capacities would leave small exp ratios around 5,6,7, which constitutes inefficient ratios. That’s why long barrels are utilized on 264 Win Mag, 7mm Rem Mag, 300 RUM and such, to increase efficiency.

There’s not a great difference in 308 WCF, 338 Fed or 358 WCF when it comes to exp ratio out of a 15” barrel. With a 20”-22” barrels they are all real efficient because of the powder capacity and the longer barrel, which increases bore volume.

If it were me I’d try to get a 165 grain Nosler Partition to shoot out of the 308 WCF. Getting approx 2,550 fps out of the 15” barrel with less recoil would be a better advantage for both velocity and delivered energy and the 165 partition will expand very well down to 1,800 fps. It will carry over 2,000 fps at 250 yards with close to 1,700 ft-lbs of energy.

If desire is heavier bullet, which will increase recoil, I’d still go 308 WCF with 180 gr or 200 gr. Either will match the abilities on game the 338 Fed or 358 WCF would produce out of a 15” barrel.

BTW 250 yards is a long poke with a 15” Encore. A 165 gr .308 would provide best ability to shoot that far and deliver the goods. Could easily reduce recoil more by reducing weight and utilizing 150 gr monos. The 308 WCF is very effective.

You could go to some light weight bullets like the Nosler 125gr BT and really zip them out there. They might even shoot better for you.

Ya know, it's probably gonna depend on what you want to shoot out of your Encore.

I like the bigger bullets but what happens at the muzzle is probably less important than what happens downrange (at 250 yards).

I suspect 'efficiency wise', you'll get more bang for your buck with the 358 but then again it'll depend on what load you're using. Try to find some real world velocity and load data from folks using a 15" barrel then you can guesstimate the efficiency yourself using the equation,

Efficiency =ME/PE

Where ME is your Muzzle Energy and PE is your Potential Energy which is defined by the NRA Sourcebook to Powder Charge x 180. That 180 represents the theoretical Potential Energy of every grain of Powder.

Here's a few simple examples:

358 Winchester (3.07cc) 0.358 Dia. 250 gr JHP with an SD=0.27866. Using 32.5 gr of IMR4198 (51,700 CUP) at 2045 fps.

This load gives us an ME of 2321.89 ft•lbs. But at 32.5 grs it gives us a PE of (32.5x180) 5850 ft•lbs of Potential Energy. So calculating Efficiency then becomes:

Eff=ME/PE or 2321.89÷5850 = 0.396896 rounded or about 39.7% efficiency.


A similar load in 338 Federal using a 215 gr bullet having an SD=0.26885 over a max 46.0 gr load of Varget (53,100 psi) at 2452 fps gives us an ME of 2870.74 ft•lbs and a PE of 46.0x180=8280 therefore this load gives an efficiency of

Eff=ME/PE or 2870.74÷8280 = 0.34671 rounded or about 34.7% efficiency.

Last one, a .308 Winchester (3.43cc) using a 180 grain JHP SD=0.27106 using 33.5 grs of IMR4198 giving us 2350 fps at 51,600 CUP.
This load results in an ME of 2207.61 ft•lbs and a PE of 6030 so our efficiency is then

Eff=ME/PE or 2207.61÷6030=0.366105 rounded or about 36.7% efficient.

But these are just numbers using loads not from a 15" barrel so your actual Eff numbers will vary. You'll have to track down some reliable numbers yourself and plug away like I did above.

OR

As a wise man once said, "To hell with efficiency, give me performance!"

Like I said earlier, I like the big bullets but it's more important to know what the bullet is doing downrange than at the muzzle.

Just my random thoughts on the matter. Good luck.

I've played the Contender/Encore game and they are fun. I've had a few Encore/Contender barrels that wouldn't shoot as well as I wanted. They went down the road or were re-chambered to something else.

I could really like the 338 Fed or 358 win in an Encore.

With that said, I'd think about this in a different light and start with - who cares which is more efficient? The issue, as you know, is attaining and retaining bullet velocity. Given your stated 250 yard max, I wouldn't sweat either cartridge. I have a 338 Fed in a Kimber MT and its going elk hunting at the end of the month. It loves 185 TTSX and launches them at 2700 and group sub-MOA with H322. In a rifle it is still a 350 yard gun. I'd guess the 358 win is the same deal. Both will be handloading propositions, both have plenty of useful bullet options, and both will recoil more than a little. To me they are same-same - but I'd lean 338 Fed simply because the same weight bullets will have a higher BC.

Have fun and let us know which way you go.

Someone mention using a 165 gr. bollet in the .308. I concur most heartily.

There was an article on one many sites I go to, or maybe it was in a gun magazine. THe author wrote on what he considered was the most efficient cartridge. After much shooting and thought he said he believed the .35 Whelen was the most efficient considering powder burned, velocity and I forget what else he mentioned. Based on my use of the cartridge, I think he may have a point. I don't know what a .35 Whelen would feel like regarding recoil but I thought I'd just mention that article.
If the choice were mine considering the cartridges mention by the OP. There are no flies on the .308 and it works well even in short barrels. If I were to go larger, I'd look at the .358. Be interesting to see which way he goes.
PJ

I have an XP-100 in .338 Federal that I usually run with 45 gr Alliant Varmint or 44 gr TAC, which are moderate loads probably giving around 2300 fps in the 15" barrel. I use the Hornady FTX 200 for hunting, which will open reliably at lower fps than the 200 Speer.