.458 Socom or .450 Bushmaster?

Shooting from my CMMG Anvil, using 458 Socom, on my Chronograph a 300gr JHP using 43.5 grains of Reloader 7, CCI Large Magnum Pistol primers it averaged 2065 fps. I could go hotter but Three shots at 100 yards measured in at 1.15" minus the bullet diameter of .458 equals .692 grouping, that is pretty good out of a AR
 
Last edited:
Hitzy said:
Wait a few months and the 350 Legend will be another AR option.
P1000181.jpg
Click to expand...

Yeah but 160gr bullets going the same speed as 250gr in a 450bm...
 
Hitzy said:
You can hold 10 of these in a mag, same body as 223, no proprietary pieces needed.
Click to expand...

Fair enough. I didn't really think of that part, magazine limits are not something I think much about as I mostly shoot bolt guns... One of these days my AR will get built and then I'll be more interested in mag caps...
 
If I had to choose I'd go 458.
Better choice of projectiles, unless a 250FTX is what you want to use. It seems to be the best bullet choice for the cartridge since it was designed for these velocities.
The 450BM headspaces off the case mouth while the 458 does not. Not a huge deal breaker but 450 is not as safe of a load for that reason.
According to the RCMP and their bulletin no magazine that will work with 223 is allowed to hold more than five 223 which limits all of them to 2 rounds of 450/458 unless you can buy proprietary magazines that are not just a STANAG pattern magazine body with a different follower. It must not be able to hold 223/5.56 to get around this. Not "law" yet but I wouldn't want to have to go to court to fight it.

If you're building a restricted rifle I wouldn't bother at all though, an expensive paper and gong plinker that beats up your shoulder and isn't much good past 200 yards isn't really an attractive range toy to me. Also opening up the bolt face that much is not leaving much material which would lead me to believe there will be more broken bolt lugs than with cartridges with a smaller head.

That CMMG Mutant would be a really nice rifle to try a conversion like this. They enlarged the bolt to make it handle x39 better which would benefit these cartridges. I've also never understood why that rifle got a restricted FRT, there is less compatible between it and an AR than there is between any of the other current non restricted ARish rifles.
 
Last edited:
cr5 said:
If I had to choose I'd go 458.
Better choice of projectiles, unless a 250FTX is what you want to use. It seems to be the best bullet choice for the cartridge since it was designed for these velocities.
The 450BM headspaces off the case mouth while the 458 does not. Not a huge deal breaker but 450 is not as safe of a load for that reason.
According to the RCMP and their bulletin no magazine that will work with 223 is allowed to hold more than five 223 which limits all of them to 2 rounds of 450/458 unless you can buy proprietary magazines that are not just a STANAG pattern magazine body with a different follower. It must not be able to hold 223/5.56 to get around this. Not "law" yet but I wouldn't want to have to go to court to fight it.

If you're building a restricted rifle I wouldn't bother at all though, an expensive paper and gong plinker that beats up your shoulder and isn't much good past 200 yards isn't really an attractive range toy to me. Also opening up the bolt face that much is not leaving much material which would lead me to believe there will be more broken bolt lugs than with cartridges with a smaller head.

That CMMG Mutant would be a really nice rifle to try a conversion like this. They enlarged the bolt to make it handle x39 better which would benefit these cartridges. I've also never understood why that rifle got a restricted FRT, there is less compatible between it and an AR than there is between any of the other current non restricted ARish rifles.
Click to expand...

Use these mags

https://truenortharms.com/ar15_default_store_view/asc-5-round-450-bushmaster-magazine.html

The internet tells me that they will work with .458 Socom & .50 Beowulf as well.
 
cr5 said:
If I had to choose I'd go 458.
Better choice of projectiles, unless a 250FTX is what you want to use. It seems to be the best bullet choice for the cartridge since it was designed for these velocities.
The 450BM headspaces off the case mouth while the 458 does not. Not a huge deal breaker but 450 is not as safe of a load for that reason.
According to the RCMP and their bulletin no magazine that will work with 223 is allowed to hold more than five 223 which limits all of them to 2 rounds of 450/458 unless you can buy proprietary magazines that are not just a STANAG pattern magazine body with a different follower. It must not be able to hold 223/5.56 to get around this. Not "law" yet but I wouldn't want to have to go to court to fight it.

If you're building a restricted rifle I wouldn't bother at all though, an expensive paper and gong plinker that beats up your shoulder and isn't much good past 200 yards isn't really an attractive range toy to me. Also opening up the bolt face that much is not leaving much material which would lead me to believe there will be more broken bolt lugs than with cartridges with a smaller head.

That CMMG Mutant would be a really nice rifle to try a conversion like this. They enlarged the bolt to make it handle x39 better which would benefit these cartridges. I've also never understood why that rifle got a restricted FRT, there is less compatible between it and an AR than there is between any of the other current non restricted ARish rifles.
Click to expand...

The 450 bushmaster in the AR15 uses a proprietary magazine made by bushmaster. I have not had any issues going through game checks in BC where conservation and rcmp officers were present.

I also use a custom bolt of stronger alloy, the face is even larger to allow it to be used with both 450 bushmaster and 30rar at pressure in excess or 55,000psi with no failure to date.

I believe the Hornady ftx is just their pistol bullet. I have had good results with the rem accutips on game, it is a rifle bullet designed specifically for the cartridge.

With Ruger now selling more rifles per year in 450 bushmaster than any other caliber, win is loading ammo, federal is loading ammo and rem is coming out with more options as well.

458 and 50 beo are way behind in availability now
 
mileageman said:
Use these mags

https://truenortharms.com/ar15_default_store_view/asc-5-round-450-bushmaster-magazine.html

The internet tells me that they will work with .458 Socom & .50 Beowulf as well.
Click to expand...

If you look closely at the pic, that mag has the Bushmaster logo on it, I believe ASC has been licensed to produce them.

Ruger is making 450 magazines now as well, part #90679, I am going to buy one to see if it is any different.

The 450 uses a true single stack design, there are steel inserts down both sides of the magazine inside to prevent a double stack which are not found inside 458 or 50 beo mags. I wouldn't believe everything posted on the net. I have not experienced trouble free operation with 50 beo in a 450 mag
 
Brian46 said:
The 450 bushmaster in the AR15 uses a proprietary magazine made by bushmaster. I have not had any issues going through game checks in BC where conservation and rcmp officers were present.

I also use a custom bolt of stronger alloy, the face is even larger to allow it to be used with both 450 bushmaster and 30rar at pressure in excess or 55,000psi with no failure to date.

I believe the Hornady ftx is just their pistol bullet. I have had good results with the rem accutips on game, it is a rifle bullet designed specifically for the cartridge.

With Ruger now selling more rifles per year in 450 bushmaster than any other caliber, win is loading ammo, federal is loading ammo and rem is coming out with more options as well.

458 and 50 beo are way behind in availability now
Click to expand...

That's good to know, I wasn't aware they had their own magazine.
I'm sure i read somewhere that the 250ftx was designed for cartridges like these. It supposedly has a little thicker jacket to handle being pushed 2000+ fps. Like the Hornady XP line of pistol bullets. I had to shop for those specifically when loading hot for my 460S&W.
 
alberta tactical rifle said:
Not for much longer. We just ordered a TON of barrels for these calibers.
Click to expand...

I was talking about factory ammunition of any manufacture on Canadian shelves. For a company like Ruger to come out and say they have sold more rifles in 450 bushmaster last year than any other caliber is huge.

Will the FA upper have the ejection port opened up to accommodate the larger rounds?

Interested in a 30rar barrel if that is possible?
 
Brian46 said:
I was talking about factory ammunition of any manufacture on Canadian shelves

Will the FA upper have the ejection port opened up to accommodate the larger rounds?

Interested in a 30rar barrel if that is possible?
Click to expand...

Nope. There was to much push back from guys about the larger port opening on the SS uppers so we have revised the programs to only make the smaller mil spec size port openings.

A 30Ar could be done, we would need to procure a reamer, gages and test fire ammo and bolt and you would need to provide detailed specs on contour, length and port location and size. IF you have a bolt we could use it and it would save you some $$
 
alberta tactical rifle said:
Nope. There was to much push back from guys about the larger port opening on the SS uppers so we have revised the programs to only make the smaller mil spec size port openings.

A 30Ar could be done, we would need to procure a reamer, gages and test fire ammo and bolt and you would need to provide detailed specs on contour, length and port location and size. IF you have a bolt we could use it and it would save you some $$
Click to expand...

I was thinking it was just barrels you were selling along with the receiver sets? Sounds like you are selling completed rifles now? What is the build time on something like that?

I was going to have the same guy who did my ACR bolt build another and do the assembly since he already has done one

An AR performance bolt could theoretically be used with face opened up, port size would need to be figured out as ACR is different. An adj gas block would allow fine tuning. I would like a light contour barrel or fluted med contour if the same weight in 18.6"

I have lots of factory ammo
 
458 socom. Because of shoulder.

For ammos I'd favor 458 socom too. Much better bullet selection if you're reloading. 450BM is more common, but that's irrelevant as long as you can get 458 ammos. Look at it like 300win mag vs 7mm Rem Mag: 300WM is a lot more common (maybe 10X), but you can get 7mmRemMag everywhere, so it doesn't matter.

You get to use your 223 magazines. Only 4 rounds will fit in a pistol mag, as opposed to 5 rounds in a rifle 450BM, but if you have 10 or so pistol mags, you save on buying new magazines (or not, nobody has ever died of too many mags!)
 
alberta tactical rifle said:
Nope. There was to much push back from guys about the larger port opening on the SS uppers so we have revised the programs to only make the smaller mil spec size port openings.

A 30Ar could be done, we would need to procure a reamer, gages and test fire ammo and bolt and you would need to provide detailed specs on contour, length and port location and size. IF you have a bolt we could use it and it would save you some $$
Click to expand...

Would you still do an enlarged port by special request? I decided to wait for the FA uppers for my 2 builds, one is a 50Beo
 
alberta tactical rifle said:
Nope. There was to much push back from guys about the larger port opening on the SS uppers so we have revised the programs to only make the smaller mil spec size port openings.
Click to expand...

Curious as to why people took issue with the larger sized port opening?

I don't need the larger opening on my uppers but I didn't see any negatives to having it either. Did it cause compatibility issues with some parts? The one I assembled was fine.
 
jiffx2781 said:
Curious as to why people took issue with the larger sized port opening?

I don't need the larger opening on my uppers but I didn't see any negatives to having it either. Did it cause compatibility issues with some parts? The one I assembled was fine.
Click to expand...

Too many internet experts expressing that the bolt is not fully supported and apparently this create some problem that only a few claim to be aware of.
There is no compatibility issues. Several of the BIG manufacturers offer the larger ports and there does not seem to be any real and documented problems but what do I know? I just make the stuff, test it, shoot it and then reload for it.
 
You must log in or register to reply here.
Back
Top Bottom