New project in the works

Josh

Well-Known Member
#1
It's been a long time since I logged in or posted, but I'm still kicking! There has been a lot going on in my slice of paradise which has kept me from my hobbys. But, I have been working on a back burner project as the time permits.

Today I present to the group my 450 Bushmaster build. This cartridge normally runs at 38K psi but with the Savage 10 action it will safely handle the 62K psi of a 308. So I plan on working up some loads in the 45 Colt range as well as standard 450 loads. But I also plan on making a few nosebleed rounds just for the experience.

So I made a cast of the chamber and found it to be about perfect for what I intend. The throat is generous in length but shaped very well, the bore is also a hair tight at 0.449". Here is a crude drawing of my measurements. 2173.jpeg

Yeah, I know I drew the rifling as left hand while it is right (crude drawing remember?) The twist is also not the normal 1-24" that comes with a 450 Bushmaster but the 1-16" normally found on the 45 ACP. I believe this will rob me of some velocity, but the versatility to shoot anything from 185 gr HP's to 550 gr cast is appealing.

Now, I have seen that this cartridge normally uses generous amounts of Lil' Gun and H-110 but when I start loading for the standard power loads I believe we will use 458x2" American data and start with IMR 4198, IMR 4895 or IMR 4064. I would prefer to keep the launch as soft as possible. With all this said, I think I will try the 3 Lee moulds I have in my 45 cal collection, the 230 TC, 255 RF, and 300 WFN.

So, hello again and what do you think?
 

Ian

Well-Known Member
#3
Reloder 7.

I opted for the .458 Socom because of the typical 1:24 Bushmaster twist, not suitable for heavy bullets loaded below the speed of sound. Yours doesn't have that issue. The .45 Raptor uses a 1:16 for 2300 fps/300-grain bullets, if that's any help.
 

Josh

Well-Known Member
#4
Reloder 7.

I opted for the .458 Socom because of the typical 1:24 Bushmaster twist, not suitable for heavy bullets loaded below the speed of sound. Yours doesn't have that issue. The .45 Raptor uses a 1:16 for 2300 fps/300-grain bullets, if that's any help.
The Socom is a 1-14 right?

That's the velocity I'm looking for, a 300 at 2300 or so sounds fun but brutal. Most of this rifles life thought will be shooting 300's at 1200 fps or so.
 

fiver

Well-Known Member
#5
I think I would try that LEE 255 at about 14-500 fps. it should snuggle into that throat pretty well.
I'd start at about 18grs of 2400 and move ahead from there, 19-20 should be about right.

rl-7 would be a good powder, so would AA-1680 and as far down as 3031.
 

Josh

Well-Known Member
#6
I've got a slew of fast rifle powders, not sure what I want to run first. I'll probably shoot some 45 ACP and 45 Colt style loads first just to get the bore seasoned. It will be a bit before I get the SiCo brake for it and the Leupold vx-3i so I will run a spare scope and cope with the bare muzzle.
 

RBHarter

Well-Known Member
#7
Hi !
I did a 45 Raptor with a 1-16 . It was fun with 2000-2200 250-265s . It tips about 6.5# . 350s brought any fun to a stop around 1850 fps .
A couple of yr ago a guy had an adjustable mould and something in 458 dia with a 16" twist . His goal was to see where the 16" twist would actually not stabilize a 2 a long nose RNFP . If I'm remembering correctly he got to like 900gr and decided he had had as much fun as he cared to.
Not long ago I ran a few 1100 fps NOE 460-543 (I want to say a Lyman 459132 copy) in an 1895 G . It made round holes with I believe a 1-20" twist I think I'd like to try a few in the Raptor .

The Raptor calls for 460 S&W dies , bullets and data .
Did you know the bulk of 460 data is rated at 45kpsi ?
Anyway after a few hot Colts and entry level 454 type loads of Unique I stepped up to the plate and loaded a few of the 350s with H322 and got reasonable results for flopping around in the dark . I think after I fix the stock crack and get the pillars in it and a couple of comfort mods I'll try the 535gr monster slayer in it as a sub .

Quick Load says like 22 gr of 322 in a Colts case is under 25kpsi so I tried 18.0 with the custom 453-350 RNFP . To clear the action I had to seat just a little deeper than intended so the 4.0 reduction isn't as much as it looks like . I got 1280 fps in a 16" 1-32" twist . Absolutely floored me . I wanted it to stay under 1100 MV .....back to Unique I guess .
 

Josh

Well-Known Member
#8
Excellent info, being that case capacities are almost identical, I hope to achieve similar results. If I can get a 300 gr cast close to 1800-1900 fps I will be in cast heaven.

This one weighs in at 6.8 lb without the scope or muzzle brake, and I hope that the brake lets me comfortably get into that 18-1900 range.
 

fiver

Well-Known Member
#9
a 300 at that speed might not be too bad with that stock shape and a brake.
I know 435grs. ceases to be fun just over 1600 in an 86 type rifle, it has a little more fun room but it goes away rapidly as the fps increases.
 

Josh

Well-Known Member
#10
That's about as far as I really want to push things, I'll have to try some 405's and the like in it, but I know they won't be the norm. This kinda scratched the itch for a Siamese Mauser in 45-70.

Also as a side note, that stock was converted from 4.4" spacing to 4.27" spacing to match my old action. Not to bad of a process but it does involve the skilled use of a heat gun.
 

Josh

Well-Known Member
#12
Josh i would like to hear about the gun and where the different parts were found. I have thought about 45/70 on one of the savage actions.
Kevin,

This idea all started a few years back when I first found Siamese Mausers were a thing. Unfortunately in my area they were either unavailable or very expensive for an already converted rifle.

So, fast forward to about a year ago, I found the 450 Bushmaster cartridge. It wasn't what I was expecting, I thought it was proprietary brass and funky rebated rims and anemic performance, this isn't so, it is just a shortened 284 Winchester case running at sedated chamber pressure to keep AR-15's from blowing apart. In this form it pretty much duplicates factory 300 gr 45-70 ammunition, that in itself impressed me.

Moving to the rifle, I found an old Savage 10 in 243 Win for $200. It is a stagger feed 4.27" action screw spacing receiver, I later came to find out that really only Boyd's makes affordable stocks for this particular 4.27" action. So I fiddled with a stock from a new Savage 12 FV which has the updated 4.4" hole spacing, with a bit of work I converted the stock to the old 4.27" spacing, it involves moving the front action screw hole.

On to the magazine, first this rifle is stagger feed, which means it feeds like a Mauser or Remington 700. The updated actions feed from the center or "center feed" they can in many cases feed empty brass casings due to their direct line to the feed ramp and chamber. I may run into some feeding issues with the stagger system and WFN or LFN style bullets, time will tell but I will be getting a center feed setup soon and plan to correct that problem before it starts.

Now the barrel, it is a Rhineland Arms QPQ treated barrel measuring at 16.5" long and of the Savage "Heavy Magnum" contour with a barrel diameter before the threaded muzzle that measures 0.810". It features a 1-16 twist, which should stabilize everything this side of a sharpie pen. It is finished with a threaded 3/4-24 muzzle with a hunting style crown. Special note, 3/4-24 is an odd thread for the 450 Bushmaster, the only company that sells the correct brake is SilencerCo and Brownell's is the exclusive dealer. At $90 it isn't cheap, but it is an effective brake. This particular barrel could have enjoyed a slower speed/feed rate on the lathe when turning down the blank, it exhibits some minor roughness from too much metal being removed at once. All that said, the bore and chamber are as close to perfect as I could ask for. All in all for $140 bucks for a Melonite treated barrel I am very pleased.

When you combine a strong bolt action with a high performance and low pressure cartridge, you can enjoy the ability to safely "hot rod" the cartridge, this is where it shines. The 450 Bushmaster enjoys almost identical case capacity as the 45 Raptor, 460 S&W, 450 Marlin, and 458x2" American. This means the load data for these cartridges is a good jumping off point for the higher pressure loads. But as stated above, your shoulder will likely be your first signs of high pressure!

All in all I expect loads from this rifle to walk hand in hand with Marlin 45-70 loads, which is all I can ask from this combo. This particular build was also pretty easy on the budget, I'm in it $350 so far and plan on about $100 more for the rifle, the scope will be extra.
 

Kevin Stenberg

Well-Known Member
#14
Did you have to special order the barrel? Its hard to find the standard heavy calibers. 35 calibers are listed different places but out of stock. And generally run 250$+
Do the heavy magnum bolt faces work for the Bushmaster?
The problem i have is i'm a lefty. And all parts are scarcer than normal parts.
 

Josh

Well-Known Member
#15
Did you have to special order the barrel? Its hard to find the standard heavy calibers. 35 calibers are listed different places but out of stock. And generally run 250$+
Do the heavy magnum bolt faces work for the Bushmaster?
The problem i have is i'm a lefty. And all parts are scarcer than normal parts.
These barrels are mostly in stock, and barrels are for either action type. You need a standard 308 bolt face (0.473") these run about 140 plus shipping.

http://www.troupsystems.com/product-category/barrels/
 

Ian

Well-Known Member
#16
I bought a left-handed Savage rifle in some caliber I didn't care about just for a build. Grab a pawn-shop special for the action, ditch the stock for a Boyd's of your choice, swap the barrel out, glass bed it, stick a scope on it and you're set.
 

Kevin Stenberg

Well-Known Member
#18
In my case its getting the money to keep up with the needs! LOL
I have an extra 308 bolt face and an left handed action that i was going to mount either the 223 or 7TCU barrel on. I will now have to start looking for another action. Boy it never ends. And i just told the wife i had all of the rifles i needed.
 

Josh

Well-Known Member
#20
Well, it didn't last long, packed up for a trip to the Cerakote guy in FL along with a few others.

It will come back "battleship gray" for eventual placement in a Nutmeg laminate stock. received_1436274776478187.jpeg