7.62x51mm "Black" rifle conversion to 358 Winchester?

[REDLINE]

In regard to the various AR10s and other 7.62x51mm chambered semi-auto battle type rifles by various manufacturers;'

To convert any of them to 358 Winchester (parent case is 308 Winchester), is there any other requirement outside of a rechambered barrel?

And, could a rechambered barrel, from 308 Winchester to 358 Winchester, be realistic in and of itself?

I'm just thinking 358 Winchester in a battle type rifle would be pretty sweet, based on ballistics and efficiency over 308 Winchester (in a 16" barrel).  In terms of handloading the 358 Winchester, bullets could range from anything in the .357 caliber pistol bullet lineup to the super heavy 280gr Swift A-Frame, and everything in between. 

[Yondering]

I'd guess in a gas system like the AR10, you might have to use a different sized gas port with a .358 barrel. I'm not sure what you'd have to do in a non-gas operated system like the HK 91, although those are not an easy barrel swap anyway.

I do like the idea of the .358 in a semi. I don't own one, but my 35 Whelen bolt gun is my favorite hunting rifle; similar concept, the 35 Whelen is to the 30/06 what the .358 is to the .308. There is a pretty decent step up in power when opening up the case to the .358 bore. I don't know about the .358 in a semi, but 4,000 ft-lb is not out of reach for the 35 Whelen in a bolt gun.

I haven't had good accuracy results with .357" pistol bullets, but they are fun to shoot, and fragment like varmint bullets. The 220gr Nosler Partition is just about perfect for hunting.

[sqlbullet]

I also like the idea.  I have a CETME kit laying around somewhere I have never built up.  It might be a candidate.

It would not be cost effective to rebore, rifle and chamber a 308 barrel to 358.  You would want to start with a 358 blank and have it reamed for the chamber you want, and then contoured for the target action.

There are a few threads out there suggesting the Paladin Machine can cut a barrel for you for about $500, which is about the cost of a match grade AR-10 barrel from Noveske.

Also, this company offers a 358 Winchester AR-10 option.  Looks like an upper will run you about $1800 from them, and a complete Armalite lower with a free float flat top upper is about $2500.

Edit - If you scroll to the bottom of that link, those guys also offer a 450 marlin AR upper...

[Yondering]

I also like the idea.  I have a CETME kit laying around somewhere I have never built up.  It might be a candidate.

I have a PTR (HK) 91, but don't know as much about it's predecessor, the CETME. Do those use fluted chambers too? If so, that might be one of the few cases where it'd be worth having the 308 barrel re-bored to .358". I would certainly prefer my 91 in .358, that would be cool. I saw that PTR did a limited run of these in .243 at one point, I wonder if they could be convinced to do a run in .358 Win? Probably not enough demand, but fun to dream about. I'm in the process of welding a scope rail on the receiver of my 91 at the moment, fun side project.

[REDLINE]

Well good.  I was a little afraid I'ld just be told I was crazy.  Then again that's probably a little true anyway.

It would seem there are a few ways to go about it from what you guys have said.

And even though I'm really just dreaming as far as the near future is concerned, I really did put a lot of thought into it and feel a 16" barreled semi-auto with at least 20 round capacity in 358 Winchester would be sweet.

Since I'm still dreaming for now, it's the FNH SCAR 17S that I want chambered in 358 Winchester.  Maybe someday I can make that happen.  I'm thinking it would work very well for all of hunting, self defense, and just plain old fun. 

And since I'm still dreaming at this time, Schmidt & Bender makes a scope that I thought would work really well to top things off.  It's their Police and Military Forces model called the 1-8x24 PM ShortDot.  So you get 1-8 times magnification with a reticle, illuminated or not, inconjuction with a red dot sight all in the same unit.  It's pretty cool I think.  If you care, here's a link -

http://www.schmidtundbender.de/en/products/police-and-military-forces/1-8x24-pm-ii-shortdot.html

It sucks I'm not even prepared to start saving for all that at this time.   But if I live long enough I'ld say there's a real posibility of it happening down the road.

[Ramjet]

Well unless you enjoy doing all that work it is hard to find a cartridge as efficient as the 338 Federal I have a DPMS lite hunter it is a great all around rifle the capacity to bore is outstanding. Selection from 180-225 grain bullets offerings from Barnes and Nosler make this a great caliber for the AR10 platform. Uppers readily available. I like the 358 but think the 338 is superior in so many ways.

[Yondering]

The .338 Federal is an interesting round as well, being the same thing as the 358 but with a .020" smaller bore. Of course, the larger bore is still more efficient. As handloaders, we know the larger bore in the same case, loaded to the same pressure, is always more "efficient", but a lot of the 358 factory loads don't reflect this, as they aren't pushed to the same levels as the newer 338 Federal. .358 bullet selection is similar and more suited to the velocity of the .358 round IMO; many of the .338 bullets are designed around the faster .338 Win Mag. 150-250+ gr jacketed bullets are available for the 358 bore.

[REDLINE]

What Yondering said, plus in this particular case the .358 is a larger caliber yet than .338 without going to really large calibers like .45 and up.  Add in the efficiency factor in a fairly short 16" barrel, like Yondering brought up, and the .358 Winchester looks better yet.

BTW Ramjet, don't take this as me trying to change your mind on your choice.  Not at all.  I'm just explaining further why I would still choose the 358 Winchester for me.

[Ramjet]

Look at the ballistic coefficient of 338 225-250 grain BT bullets vs 358, 338 wins out. I also do not really agree with Yondering in that the bullets such as the partition and Barnes X or even the 180n grain Nosler bonded perform superbly in the 338 Federal. Don't get me wrong but the 338 Federal IMHO is the perfect balance of power and ballistics for a medium range hunting rifle. 333 OKH right?

I like the 358 alright but think the 338 outperforms it. No project for me I already have and shoot it and have taken game. DPMS Lite Hunter.

But anyways I will look forward to reading about your adventure.

[Yondering]

Look at the ballistic coefficient of 338 225-250 grain BT bullets vs 358, 338 wins out.

Look at it this way: The 358 can push a 225gr as fast, or faster, than the 338 pushes a 210gr. (This is also true of the 338/06 vs 35 Whelen; the larger bore is just a little more efficient.) BC of Nosler's partition bullets are .400 for the .338 210gr, and .430 for the 358 225gr. So, the 225gr 358 is moving about the same speed, with a higher BC, and more mass.

That is the appeal of the .358 (or 35 Whelen if you make the same comparison based on the /06 case). The 338 Federal is a fine cartridge, but you can't reasonably claim that it's more efficient or works better.

Good discussion though.

[REDLINE]

What do you see the performance advantage(s) being in 338 Federal over 358 Winchester from a 16" barrel in a black rifle type setup?

[Yondering]

I like the 358 alright but think the 338 outperforms it.

This is probably true with factory loads, more because of marketing than physics though. The 338 Federal is a new round that has had a bunch of money spent on it in recent load development. The 358 is an older round, less popular, that the ammo companies aren't spending much time on. It is not true for handloads.

One of these days someone in the gun industry will start marketing the 35 caliber again, and everyone will suddenly "discover" how great it is. Until then, those of us in the know will just smile and nod. 

[Ramjet]

Well if you can hand load the 358 to optimum performance then so you can also load the 338 Federal to even better. B.C. With the boat tail bullets.

[REDLINE]

I see what you're saying.  For my intentions though, boat tail bullets won't be necessary.  I'm only looking at it for short range applications (150 yards and less), and to work in a pinch for medium range (250 yards and less).

In a longer barreled (20"-24") bolt action setup I would agree more but then wouldn't consider either the 358 Winchester or 338 Federal.  Actually then the 35 Whelen that Yondering is so fond of would begin to look better yet, not to mention one of the 338-06 variants.

No doubt though, I do get the arguement for the 338 Federal.  I'm certainly not knocking it.

[sqlbullet]

Well if you can hand load the 358 to optimum performance then so you can also load the 338 Federal to even better. B.C. With the boat tail bullets.

I don't know that this is always true.  I am not familiar enough with these two calibers to speak to them.

But, I know that in the 10mm Auto V 40 S&W fight that is not true.  Plenty of ammo makers push the 40 to it's full potential.  About the only thing a handloader can do is lower cost per round.  However, the 10mm gets lots of improvement over most factory loads.  Only Underwood is really tough to beat.