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The How and Why of a Bolt Action .450 Bushmaster Hunting Gun

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They say that necessity is the mother of invention, and that old bromide generally holds true. A few years back, the local lord decided to ease back on regulations that pertained to the hunting of the king’s deer in our most beautiful and tragic of states. But was it really a mercy?

I’m going to come out swinging and say that the regulation of cartridges for hunting is one of the most unnecessary and hopelessly idiotic things that a government body can waste our tax dollars enforcing. It’s right up there with the strict control of short barreled rifles, suppressors, and interstate speed limits.

We live in a century in which technology allows me to have a sandwich sent to my coordinates with the press of a button on my pocket communicator and yet my elected officials see fit to make themselves relevant by forcing me to hunt my own deer with a cartridge that would’ve been considered weak sauce in 1900.

So it came to pass that hunting with straight-walled cases between 1.16” and 1.8” and of .35 caliber or larger became the law of the land. I could dive deeply into the “reasoning,” but frankly, it’s not worth trying to understand why these utterly arbitrary guidelines were established. The point being, Michigan and several other states need to get with the times and let us hunt with modern cartridges.

The original intent of the state was to make hunting with what are essentially pistol cartridges legal in the shotgun zone. The idea was to allow cartridges like the .357 Mag, .44 Mag, and .45 Colt in short range rifles that were less powerful or equal to a 12ga slug, because you know, logic.

The state certainly got one-upped because it turns out that there are myriad law-compliant cartridge options that exist that are vastly more powerful than a simple slug gun and, at normal hunting distances, far more powerful than many centerfire bottleneck calibers.

To illustrate the stupidity of this law, it’s illegal to use a common and very effective .243 caliber rifle, a 6.5 Grendel, or a .223 Remington. But it’s perfectly legal to use something like the .50 Beowulf, which in a 400 grain loading has power equivalent to a .50-90 buffalo rifle of the same bullet weight.

Being a modern hunter, I decided to go ahead and do something to satisfy the state while at the same time beneficial to those in my same position. I could’ve gone with a garden variety AR, but I decided to use my .308 Mk4 rifle as a base for the project since many people these days have underused bolt guns they originally bought for hunting or target shooting. So what caliber would meet both my demands and that of the law?

My first inclination was to look at calibers that would fit into an AR-10, as my .308 was of that magazine size. My only real option was a relatively obscure caliber called .45 Raptor. It is a very well thought out cartridge that is essentially a .460 S&W magnum case with a .308 rim. It claimed to be able to fire a 200gr bullet at over 2800fps from a 16” barrel. I was listening and they had my attention.

I began to dig and dig, but I was unable to find a barrel maker that would make a drop-in for a Savage small shank thread. This got me looking into other options. I eventually looked at a number of calibers and determined that none were up to my standard. That was until I looked into .450 Bushmaster a bit more than I had in years past.

I remembered when the round was introduced and it was all about Jeff Cooper and how he called it ‘Thumper’ or some shit. All I could think of was the rabbit in Bambi when I read about it. Say what you will, but Cooper had some good and very borrowed ideas that made for good press. His scout rifle concept was ripped right off the Nazis and the ‘Thumper’, well that wasn’t what people thought it was.

The Thumper thing referred to what Cooper wanted to be an infantry weapon for rear-line troops chambered in something like .44 AutoMag and was wildly panned as a bad idea. The idea behind the .450 Bushmaster came from the concept, but wasn’t really what Cooper had envisioned.

I had dismissed the .450 Bushmaster as a hokey marketing campaign to capitalize on a dead guy’s name and sell a caliber that would die off in a matter of a few years. I still think it is a stupid idea, but as it turned out, that stupid idea was within the parameters established by the silly bureaucracy of my state for deer hunting.

The .450BM, like the .45 Raptor, features the same case head as the .308, making it compatible with my existing rifle. The case is also wide-bodied and will fit in and feed from a standard AICS-pattern magazine, although at a slightly reduced capacity. A ten round Alpha Mag holds 7 .450 rounds and 8 if you squeeze.

Alpha Mags in the front, MDT polymer mag in the back. Note that there is a large amount of room in the front of the magazine. Contrary to what you may think, it does not have an impact on feeding.

So began my conversion quest.

I contacted a company called Black Hole Weaponry after I read a number of positive things about them online. They were one of the only companies that offered a drop-in barrel for my rifle. Dealing with BHW was time well spent. The folks there are very kind and knowledgeable. Another gentleman was interested in the build concept, so we decided to install a barrel on his .308 as well.

Both barrels from BHW were 1:18 twist varmint contour, the shorter of the two being 18” and finished in a matte black and the other 22” and polished.

Installing the barrels was as easy, just like on any Savage. Or so I thought. Turns out that nobody really makes headspacing tools for the .450 like they do common rounds like .308. Being a natural innovator, I decided to take the ‘YOLO’ approach and put on my flat-billed thinking-cap.

Yeah, I work on my carpet sometimes. Paint can be removed from your gun parts easily with paintbrush cleaner, which came in handy here.

 

The .450 is basically a big .45ACP, so it is able to headspace on the case mouth. I pulled the bullet on a couple cases, got out my wrenches, and went to town. I measured the cartridge case protrusion from the face of the barrel and then the gap between the bolt face and barrel face. I figured out the minimum headspace and spun those babies on.

Barrel headspaced and set. I had to cut a small notch in my proprietary barrel nut to remove it from my old barrel. Hindsight is 20/20 they say.

Stocks were put back on and scopes reattached. I was ready to rock. After a few non-serious rookie moves, I got my new law-compliant buffalo/deer rifle shooting.

Hornady supplied me with their excellent 250gr FTX loads and I was off to the races. I had fired this and calibers like it in various AR rifles over the years and really didn’t know what to expect for recoil. It may be the fact that the rifle weighs over 16 pounds or because I was expecting it to be bad, but I found the caliber to be relatively easy to shoot. I’d compare it directly to a 20ga rifled slug gun in the recoil department, but another taker at the range said it felt much more like a .45-70.

Black Hole Weaponry’s barrels provided as good of accuracy as I could’ve hoped for considering my limited round count and time frame. I didn’t bother at all with a break-in time, mostly because I consider them to be unnecessary, and just got right into getting my setup zeroed.

I discovered that the .450 heats up a barrel fast, but it doesn’t lose much accuracy when hot. Groups measured in at an average of 1.5” for three shots across the board, with the very best being 3 in one hole at 100 yards. Considering my practical range of use, that was plenty good for deer.

Despite the short OAL, the .450BM is right at home in a .308 action.

I backed off to what I consider the effective ethical distance of the cartridge and observed the drop and groups at 200 yards. The rifle performed well and averaged about 3”, with the best being about 2” for three shots. To make my life really easy, the bullets dropped a very handy 1 mil on my crosshair.

I zeroed for 200 yards to take advantage of the effective range and point-blank trajectory. I could hold dead on a deer at any distance inside the zero, which made my life easy.
After it was all said and done, I packed up the rifle in my Eberlestock pack and headed to the east side of Michigan where I was to go hunting in the early antlerless season.

Long story short, I didn’t manage to get anything, but there’s always November to take this baby out again. I was, however, able to enjoy the confidence that comes from knowing that I can sit in on the edge of a field and hit anything that wanders in with little to no special holdover or fuss.

The .450BM allows for a much greater effective range than any other legal calibers in the same restriction zones. That won’t guarantee you a kill, but it will make it a bit easier to fill your tag.

The .450 Bushmaster offers the legally burdened hunter a bit of edge in what should be a standard rifle zone. It vastly outperforms any handgun round while at the same time offering ballistics better than .45-70 and on par with the more obscure .45 Raptor in the same bullet weight, while at the same time being drop-in ready for a .308 bolt action. Unlike other options, factory ammo is available from Hornady and is top quality.

If you are looking for these qualities, look no further than a Black Hole Weaponry barrel and a few boxes of Hornady ammunition. There’s still plenty of time until most hunting seasons start, so now is a great time to upgrade your rifle.

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