Feed The Beasts
Nowadays Hornady offers 450 Bushmaster ammo with the 250-gr. polymer Flex Tip expanding (FTX) bullet, Winchester has a 250-gr. Extreme Point polymer-tipped bullet, Remington has their 260-gr. AccuTip polymer-tipped bullet and Federal offers a 300-gr. JHP. There are other brands on the market, too but excluding exotics like the lightweight ARX-style “drill bit” bullets, factory 450 Bushmaster ammo falls into the 250- to 300-gr. range.
The rounds are similar in velocity. The 450 Bushmaster 250-gr. FTX round has a published muzzle velocity of 2200 fps while the SOCOM round loaded with the Barnes 250-gr. TSX HP bullet is listed at 1990 fps. However, the standard barrel length for the 450 is 20″ with a 1:24″ twist while the 458 SOCOM standard is a 16″ barrel with a 1:14″ twist. The 4″ difference between the two accounts for about 100 fps of the velocity difference. Reverse the barrel lengths and the difference would disappear. The 450 does get a bit of a boost from being loaded to a slightly higher chamber pressure than customary for the 458 (there is no SAAMI standard for the .458 SOCOM).
What about ammo prices? Nope, not even close. A box of Hornady 250-gr. FTX for the 450 is only $31.99, or $1.60 per round from Midway USA. A box of 20 SOCOM 250-gr. TSX runs $54.99, or $2.75 each, and 300-gr. loads run around $60 ($3 per round) — and it just goes up from there.
And I thought shooting my .45-70 was expensive. Holy Schmoly, Batman! So, come feeding time, the Bushmaster seems to have it all over the SOCOM.
But wait. We haven’t talked about magazines yet. Remember, the 458 SOCOM was required to feed faithfully from standard mil-spec mags, — and it does! The 30-round .223 magazines hold ten 458 SOCOM cartridges, the 20-round USGI mags hold seven while 10-round mags hold five. The SOCOM’s reputation with 30-round .223/5.56 polymer Hexmags seems to be flawless. Those wonderful PMAGs? Nope. The center rib down the inside front prevents them from being usable with the 450 and 458. Lancer mags are fine when modified for the 458 by Wilson Combat or Tromix.
On the other hand, the only magazine Bushmaster offers for the 450 is a short five rounder. Why? Because it doesn’t feed worth a darn in larger magazines. Several magazine makers have tried making or modifying 7- and 10-round mags, and failed. As mentioned, the 450 Bushmaster case is a tapered but straight walled case while the 458 SOCOM is a shorter, fatter bottlenecked case.
Therein lies the rub — standard .223 magazines can barely contain five of the skinnier 450 Bushmaster rounds. The cartridges do their best to double stack and also frequently force the magazine feed lips wider, eventually ruining the mag and allowing the cartridges to self-eject.
The sole company still offering a 10 rounder for the 450 is Tromix Lead Delivery Systems. It’s a highly modified Tapco Intrufuse magazine, costs $50, and is limited to one per customer when available