Home Forums Hunting & Shooting Ask The Gunwriters 458 Win. Question

How much barrel length would you need to burn all the powder in a 458 case? I'm looking for the minimum. I'd like to go 20", maybe 21".

Would have to look up the powders used with the 458, but think most would burn in 22" maybe 20. 4198 a favorite in the 458 and it's a pretty fast burner.

Thanks Ghost. Had to quote you to read your reply, there's some friggin ebay ad right in thee middle of the screen that I can't get rid of, no way to close or move. Unbelievable.

Just looked on Hodgdon's site, and Varget seems to be the best powder. When you consider the .458 bore, lots of powder can be burnt in it in a shorter barrel. But seems to me, cutting the barrel back, would change the balance on the rifle.

That is the intent to get a quick handling, closely balanced gun.

I'm planning my own 458 Win project and will start with a 22" barrel, I can always cut it back to 20" if needed.

If I recall, Phil Shoemaker's (458Win)Old Ugly is right around 20".

It takes the same length of barrel using a 458 as it does for any other round using modern smokeless powder. Been there, tested that.
Charlie

How much barrel is that?

I don't have a 458 WM, but a 458 B&M with a 18 " barrel. Case capacity is about the same as a 458 WM. Using H4198 and CEB 258 gr. or Hornady 250 gr. Mono-Flex bullets I can get 2800 FPS no problem 1 1/2" 5 shot groups at 200 yrd.

Easy of handling my Winchester 70 458 B&M with a Ultimate stock 18" barrel 6lbs-10ozs. with iron sights.

For more Information on 458 B&M :http://www.b-mriflesandcartridges.com/458-B-M.html

Fact is the powder that is going to burn does so in the first few inches of the barrel. Barrel length affects velocity because the powder gasses continue to accelerate the bullet until it exits the barrel. A 22" barrel give an additional 4" of barrel to accelerate the bullet.

Powder burns in the first few inches, the gasses generate throughout the balance of the barrel length.
Be careful not to miss 2 important points:
1. Longer barrels reduce blast.
2. Pointability and manouverability are critical attributes for a dangerous game rifle. If you prefer a shorter barrel, it needs to have the weight to retain this important control.

John

This is worth repeating.

Pick the length that feels best in your hands. It's not like a 500 gr bullet is going to bounce off game if it's going a wee bit under 2000 fps at the muzzle.

You like 18", go with 18, like 20, go with 20, like 22, go with 22....

I've had two 458 lotts, one with a ported barrel that was just under 20", and one that was as I recall around 22". Not much velocity loss when going with a shorter barrel.

If I ever get around to getting another 458, it'll probably sport a 20" tube.

I didn't measure mine when I made it, I simply started sawing off sections until it felt the way I wanted it to. As it turned out that was 20 1/2 ".
I still get an honest 2050fps from most factory ammo and over 2150 from some others and my handholds.

As the late gun writer and African PH Finn Aagaard once pointed " a 500 gr .458 caliber bullet moving at 2000 fps make a big, bloody hole in anything it hits"
I have to agree.

AA2230 is the best powder for 450 to 500 grain bullets in the .458. You can get 2200 or 2250 fps with no excess pressure. H335 is also good. For light (350 grain) bullets use 4198 and you can get 2700 fps with no problems.

The only problem is that these loads cause the 350 and 450 grain bullets to shoot about 7" different in elevation at 100 yards.

My rifle has a 22" barrel. It has never got "hung up" when hunting elephant or buffalo in the African jesse. Try that before cutting further.

What most buyers of .458 Win Mags don't realize, or know, is how much "free bore" a typical .458 WM actually has from the factory. Unless you are having one put together by a smith and he asks you about it, a standard reamer will create a free bore of about 3/4", the same as most factory products. In effect that shortens your barrel by more than 1/2" already. That's not much, granted, but it's then very difficult to get enough of the "right" powder into the case to compensate for that "jump" to the lands.

When I bought my first .458 WM, a Ruger M77 (22") with a tang safety (which I prefer), I couldn't get decent accuracy from 350 grainers while getting one-hole groups from the 500 Hornady. I contacted John Kronfeld, who was of great assistance in explaining about the typical .458 WM "free bore". I had to seat those 350 Speers out as far as possible (1/4" in the case) to get any kind of consistent accuracy, but even then it was closer to 2" groups than 1 1/2", and that was after shooting several boxes of 350s and trying every suitable powder/primer, etc.

But that free bore served a purpose to defeat the extra high temperatures of African hunting that elevated pressures with the available powders of the era, especially those using factory fodder. The vast majority of safari hunters using a .458 WM was totally unaware of these issues.

The late Finn Aagaard, wrote an article several years ago (which I still have) on the .458 Win in which he had tested most factory ammo in five different .458s. One of those five was his own that had been re-barrelled to a 23", but he discovered in the process of these tests that handloaded with the 500gr Hornady it ONLY had 1/8" free bore compared to the others that averaged about 3/4". In his rifle, the factory loads plus his own, beat all the others, including a 25" Winchester, by upwards of 160 fps, with NO signs of excess pressure. He was getting 2188 fps from the 500gr Hornady in a factory load!

I've since owned a CZ550 with a 25" tube. The weight all up was 11.25 lbs. There was NO difficulty to exceed 2200 fps from the 500gr Hornady with several powders, H335 and H4895 in particular. A2230 wasn't available at the time. Later, before I sold the rifle, I obtained some 2230, and it was slightly faster with a couple of grains less than H335, but I never got it tested for accuracy. That rifle was more accurate than I was. The other powder I used for the 350 TSX was H4198 at 2750 fps. It too shot into MOA when I did my part. The key to that was in being able to seat those bullets long in crimping into the bottom groove.

Concerning handiness: That rifle was perfect in balance, so was never a burden in moose hunting in Northern Ontario for a week (using that 350 TSX). That's vast and rugged country. Didn't get a moose but used the same ammo on a decent bear a few weeks later at 95 yards.

Today, my Ruger #1 in .45-70 IMP (long-throat) is my ".458". It has the original 22" barrel with an "improved" throat, but little free bore using the long 500's or 450s. My bear load last fall was a 300gr TSX at 2645 fps. It's much lighter and handier than the CZ, but the recoil is MUCH greater!

Having experienced a few 1000 rounds through each, I'd recommend a 22" barrel and a weight of at least 9 lbs all up, built on a standard-length action, not the CZ which is a true magnum-length action.

Just my view from who I am.

Bob

www.bigbores.ca

One of my 458's is on a Springfield 03 action. I would say it was built in the 1950's. The barrel a a short heavy 16 1/2" in length. The gun handles superbly and I would have liked to have used it in Africa. It was built by A&M in Prescott and is original in all respects so someone had the short barrel/handy theory even back then. Have never chronographed a load from it or any other rifle. I just use book values and trust them to be close. I have had no game complain, ever. Just lucky I guess.

Zimhunter; Congrats on your .458s. Equivalent ballistics from a 22" .458 WM is possible from my #1 Ruger in .45-70 with a long throat so bullets can be seated as long as possible/practical.

But, I'm wondering -- since you've never chronographed your loads -- why you seem to believe the book values that, without doubt, were from a 24 - 25" barrel? The Ruger 77, I once had, I should have kept as it was about ideal in overall length, weight and handiness given its purpose -- except for the too long throat which the action didn't allow adequate use of. The CZ did.

Anyway, not knowing your load, you probably are getting about what my Ruger #1 was making from the 500gr Hornady before I had the mod made on the throat. It was making 2000+ fps from the factory at safe, tested psi. The long throat allowed another 185 fps. That rifle, all up, with scope and 5 cartridges in a cartridge holder on the stock goes 8.6 lbs. I don't mind shooting it, but I wouldn't want it any lighter. And it's OAL is 38.5", almost as short as yours while still using a 22" tube. I think you're loosing about 200 fps from wherever your load might be from a 24".

So yes, a 500gr at +/- 2000 fps will kill anything on Earth assuming the right bullet and placement within range. But I WOULD NOT WANT THE MUZZLE BLAST, NOR WOULD THOSE NEXT TO ME!!!!!!!!

Bob

www.bigbores.ca

Several years ago Remington printed some ballistic figures for calculating how much velocity was lost cutting back a barrel. I believe they took bore size and starting velocity out of a 24" barrel as standards. If I remember correctly loss per inch was very little from a 45 caliber barrel. They no longer publish this information where they used to. I am incorrect in as much as they use the velocity rather than the bore. It was published by Remington and is from their Centerfire Rifle Ballistics Tabel Information I printed from http://www.remington.com/ammo/ballistics/tableinfo.htm on Oct4,2003. for a rifle with 2000-2500FPS out of a 24" barrel you lose 10FPS for every inch cut below 24". 2500-3000FPS 20FPS loss. 3000-3500 30FPS. 3500-4000FPS 40FPS. I would assume Remington would not publish such information unless they were fairly confident of it's accuracy.

I've used 2 rifles chambered for a .375 H&H, the first an M70, 24" that failed to make 2600 fps from 300s, though I tried every appropriate powder at the time. My next .375 H&H had a 26" barrel and would easily grant 2700+ fps from at least two powders, one was relatively new -- RL-15 and the other, a much older powder, had similar burn characteristics: IMR 4320.

But the bore of the 26" was off center by .008" and would not give the kind of accuracy I expected, so I had it lopped to 22" in hopes of correcting the poor accuracy (It wasn't until the smith cut the barrel that its off-center bore was discovered). The rifle then gave 2530 fps from the same loads! That was a loss of 185 fps from -6" = 31 fps per inch.

From a 20", .338 Win Mag, prime handloads of 250s attained factory specs at 2660 fps, but another .338 with a 26" tube gave 2840 fps from 250s. That's an increase of 180 fps = +30 fps per inch increase. Then, I've owned several .458" calibers, and while the loss from 26" to 22" is not quite as great as in the faster .338 and .375, it still amounts to about 25 fps per inch, so that was the basis of my thinking in suggesting a loss of approximately 200 fps in a 16.5", .458, while taking into account variances incumbent in a variety of firearms and variable loads.

Also, taking into account that factory loads in .458 WM from 24" tubes usually run about 2050 fps to start with, and several manuals only grant about the same number starting out. So even giving your 16.5", .458, 2000 fps from 500s may well have been optimistic on my part.

Bob

www.bigbores.ca