My new $250 45 cal "Thumper"

Andy

Andy

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"RR" and I have yet to be named Wildcats based on the 458 Win Mag shortened to about 2.200". They are essentially a 450 Marlin without the wide belt. He picked up two guns chambered for said round and based on Turk Mausers at a recent gunshow and was kind enough to pass one over to me. :)

I put it into a budda'd milsurp mauser stock I had in my bin, after opening the barrel channel up, painting it with truck bedliner and adding a recoil pad. I had a cheap Bushnell 4X scope kicking around and voila, instant Thumper. It remains to be seen how long the stock and scope hold up, but hopefully at least long enough to develop some loads.

458x2_1_Gun.jpg



As for ammo, it's easy. Take 300 Win Mag brass, cut it to 2.20" with a Lee 45/70 Case Length Gauge, and size it in a 450 Marlin die.

458x2_1_and_3006_ammo.jpg


L - 458 x 2.2", R - 30/06

To the range this afternoon with a bunch of 350gr Hornady RN over 48.0gr of H4198. A report to follow.
 
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Yea at first we thought they were 450 Marlin, then 458 American, but the chamber is clearly 2.100" long (in fact a wee bit longer than that). I'm sticking with 2.100" so I can use the 450 Marlin dies and so forth. Another 0.050-0.100" would make little difference and it's not like I need more energy.

So it's effectively a "458 American Improved" which would make it a "458 Canadian" right? ;)
 
Andy said:
Yea at first we thought they were 450 Marlin, then 458 American, but the chamber is clearly 2.100" long (in fact a wee bit longer than that). I'm sticking with 2.100" so I can use the 450 Marlin dies and so forth. Another 0.050-0.100" would make little difference and it's not like I need more energy.

So it's effectively a "458 American Improved" which would make it a "458 Canadian" right? ;)
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"450 Canuck"??:rolleyes:
Cat
 
Andy said:
"RR" and I have yet to be named Wildcats based on the 458 Win Mag shortened to 2.100". They are essentially a 450 Marlin without the wide belt. He picked up two guns chambered for said round and based on Turk Mausers at a recent gunshow and was kind enough to pass one over to me. :)

I put it into a budda'd milsurp mauser stock I had in my bin, after opening the barrel channel up, painting it with truck bedliner and adding a recoil pad. I had a cheap Bushnell 4X scope kicking around and voila, instant Thumper. It remains to be seen how long the stock and scope hold up, but hopefully at least long enough to develop some loads.

458x2_1_Gun.jpg



As for ammo, it's easy. Take 300 Win Mag brass, cut it to 2.10" with a Lee 45/70 Case Length Gauge, and size it in a 450 Marlin die.

458x2_1_and_3006_ammo.jpg


L - 458 x 2.1", R - 30/06

To the range this afternoon with a bunch of 350gr Hornady RN over 48.0gr of H4198. A report to follow.
Click to expand...


Yes, the small bores are fun!!

Lauriespics084a.jpg
 
FOR f**kS SAKE! PLEASE STOP POSTING PICS OF YOUR 505 GIBBS! You have never shot anything with it and we all know you have one. you tell us 10 times a week.

PLEASE JEBUS! MAKE IT STOP!

on a more relavent note, Andy, give 53.5gr of RL7 a go with that 350gr RN. it;s a sweet load in my Marlin, gettign a chrony'd 2150fps
 
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Amphibious said:
FOR f**kS SAKE! PLEASE STOP POSTING PICS OF YOUR 505 GIBBS! You have never shot anything with it and we all know you have one. you tell us 10 times a week.

PLEASE JEBUS! MAKE IT STOP!
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Amphibious kicks ass!!! You crack me up dude.............and you're SOOO right too.:D
 
Range Report

Actually I consider the 505 Gibbs a medium bore - I shoot a 577 Snider ;)

Anyways, I went to the range and have a report along with some pleasant surprises.

http://www.pridham.ca/Shooting_the_458.AVI

I shot 25 rounds of a 350gr Hornady RN over 48.0 grs of H4198 and averaged about 1800fps. I knew this was a very mild load, but the velocity was about 150fps lower than I expected from the 22" barrel. But I discovered why.

458_Chrony.jpg

My Top velocity


Where the surprise came in was with my fired brass. This is not simply a shortened 458 Win Mag - have a look.

458_Fired_Unfired.jpg

L - Fired, R - Unfired

It is a bottleneck cartridge with almost no taper! The shoulder measures 0.509" (and the base is the usual 0.513") as opposed to the 0.481" I expected. The capacity of the blown out cartridge is 80.0grs of water full to the top as opposed to 76.0grs - a 5% increase. This extra capacity lowered the pressure and dropped the velocity.

The neck is very short on the 2.100" brass (0.250"), so I will be lengthening it to the max (2.200") and increasing the cartidge OAL to 2.800" which is about 0.050" from the lands with the 350gr RN.

As for dies, neck-sizing can be done with the 6.5x55 Mauser seating die.

More to follow.
 
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I found IMR4198 to be poor in the Velocity dept. as well with my .450. "max" loads yeilded approx 1900fps with the 350's. more then enough for NA game, but not what I was looking for.

keep us posted on your project. I like the stepped barrel, very cool,
 
Amphibious said:
...I like the stepped barrel, very cool,
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Thanks for the tips guys - I know I have along way to go. I plan to try heavier loads of H4198, but also RL7, H322, Benchmark and IMR3031.

As for the comments on how good the gun looks, thank you very much, but I must say it looks a lot better in pictures than in real life. It certainly is unique, and a bit of a pig IMO, which suits its character. I laughed about the stepped barrel - it's the result of the previous owner losing interest at the lathe before he got the profile he wanted. :)
 
Amphibious said:
FOR f**kS SAKE! PLEASE STOP POSTING PICS OF YOUR 505 GIBBS! You have never shot anything with it and we all know you have one. you tell us 10 times a week.

PLEASE JEBUS! MAKE IT STOP!

on a more relavent note, Andy, give 53.5gr of RL7 a go with that 350gr RN. it;s a sweet load in my Marlin, gettign a chrony'd 2150fps
Click to expand...


A litle teeched are we!:rolleyes:

Very well, if you want the pic removed, it is!

Oh bye the way there are reason's that I have not being going hunting the past few years, but they are none of your business!
 
Workin Man said:
Looks like fun Andy. Does it feed well? I don't understand though about how you neck size for this with a 6.5 Swede seating die. I'm curious as to how that works.
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It feeds very well.

Being "creative" with dies is common with wildcat cartridges. With a cartridge book and bit of luck, you can sometimes find a die that, although not used for its intended purpose, "works".

The usual neck size for 45 cal (0.458") is 0.481". The base of the 6.5x55 is 0.479", which would be a bit tight, but would work "in a pinch" (no pun intended), but seating dies always provide a bit more clearance, and in this case my 6.5x55 seating die was bang on at 0.481".

To neck size, you just lower the seating die down to the shoulder. There's a wee bit of taper in the first 0.350" (the neck length) of the die, but not enough to matter.

No need to buy an expensive die set. The first firing is a forming load, and if after four or five cycles of neck-sizing the bolt won't close, I can either size the body down a bit in a 450 Marlin (or even 300 win Mag) F/L die and be good to go again, or simply discard the brass.
 
So if you were to use a 300 WM die to push the shoulder back, you would only feed it in part way, similar to what you are doing with the 6.5 die to neck size? And all the way with a Marlin die?
 
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Workin Man said:
So if you were to use a 300 WM die to push the shoulder back, you would only feed it in part way, similar to what you are doing with the 6.5 die to neck size?
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You'd have to experiment, by moving the die down in increments. My best guess is that 2/3 rds of the way down would be sufficient.

Make note that this is a belted round that headspaces on the belt, not the shoulder, so you can do things you can't with a rimless round. For example, fireform from straight to bottleneck, and size the area around the shoulder down without affecting headspace.
 
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