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Not quite "intermediate" - .45-70 conversion?

11K views 86 replies 13 participants last post by  1biggun 
#1 ·
I fondled an empty .45-70 case and tested its fit in several magazines. This seems like it would be a NICE round for the AK platform.

I am sure it will fit in the G3 .308 magazines I tested. I still have a pile of them! The FAL mag would require a bit more work to shape the top area due to the thin size, and it would hold less rounds, again due to the thinner size. My estimate is that perhaps 12-15 rounds in a G3 magazine would fit.

The PSL mags are really too thin at the tip to handle more than perhaps 5 rounds, if that much. I think the cartridges tip too much toward the middle, but I'd have to stack it full to see exactly how that would work.

I didn't have any other mags - PSL, FAL, and G3 were all I could find. I'd like to see how those US Saiga .308 magazines would work. I wonder if Saiga .410 magazines might work too?




Looking at the rim, it seems a 7.62x54R bolt could be modified to fit the .602" base of the .45-70. There would still be enough area on the bolt to cover the rim, and considering the rim really doesn't need to be directly supported, it seems almost too easy to modify it.

The Speer reloading manual has a section dedicated to the .45-70 with loads specifically tailored to "only the modern lever actions" that can handle the "extremely high pressure" of 35,000 CUP. That really got my attention! :)

The AK action should be able to handle this cartridge no problem.
considerable hunting platform. And a home defense platform too, assuming you put a big muzzle brake on it. I'm thinking a blast-redirecting brake like on the Barrett 50. I'm pretty sure I've seen one of those, perhaps on Global Trades.




I have no idea on barrels. I assume it uses a .458 barrel but I could be wrong. I'll have to check on what's out there. I think a nice 16-18" barrel with a whopper muzzle brake would fit the bill very nicely! :D


Wheels are a'turnin!!!! :thumbup1: Someone talk me out of this! Why would this be a bad idea?
 
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#2 ·
Talk you out of it? Yeah, right.

Maybe you could take a look at a Bren mag. It's squared off at the front, unlike the PSL mag. It's made for a large rimmed case. They're affordable. They're BIG. They're thick enough to weld without blowing big holes in them.

The downside is that they have a big rib on the back for the bolt hold open lug, which might need to be ground/cut off and a new back panel attached. The mag is really just too big for anything less than a PSL bolt and carrier, but you seem to be planning on going that route so it shouldn't be an issue.

For barrels, you may want to look at Thompson Center. I believe they have 16.5" and 21" versions.



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#3 ·
Hc I read of A guy building one(45-700 on a 20 guage sagia shot gun when researching the Tromix 444 marlin conversion). .458 barrel I have been looking at the 444 Marlin and the 45-70 brass as a doner for a rebated rim round and am collecting parts for a 444 marlin/410 sagia conversion. I really want to build a 444 marlin with a rebated rim on a Yugo kit. I dont think the rebating will be that much work. there is also the possability of using 410 brass shotgun shells as well formed to make a simular round.
 
#4 ·
Rhino, I thought Bren mags had dried up? I assume you mean the .308 mags? Or the .303 mags?


Biggun,

I looked at the Saiga .410 first, but after reading the chamber pressure of a .410 is around 12,000 PSI, I decided to look more closely at a PSL-based setup.

The data on the Chuck Hawks website here:

http://www.chuckhawks.com/45-70Govt.htm

... is based on the Hornady 6th edition data. The "heavy" load is 50,000 CUP - quite a bit. I'm not sure that the Saiga shotgun actions would be up to it?????



I just pulled out the Hornady 7th edition, which states that the data listed under ".45-70 Gov't 1895 Marlin" are "held up to 40,000 CUP max"... that puts this just on the high side of normal - but still within - standard AK action pressures. And the write-up says that it will be good for anything "from black bear to moose". I'll bet!!! :D This would blow volleyball-sized holes in a man-sized target!!! :rofl:


Now, the Hornady 7th data for the "Ruger #1" does indeed put them at 50,000 CUP. Probably too much for a "G" conversion, but possibly OK for an M76 action? The 54R data from the Chamber Pressures thread here:

http://www.gunco.net/forums/showthread.php?t=35193

... is listed at 46,000 CUP. The question is how well the 46000 would handle the cartridge's 50000 CUP. That's only 4,000 difference, not much really. HRM. The Hornady manual stresses the maximum is 50,000 CUP, so the more I read it, the more I think those 500 grain monster bullets could be used with a PSL action. Oh WOW - 1300-1500 FPS in a 500 grain bullet! That would be a cool dinosaur killer!!! :rofl: And if you stayed on the left side of the charts, it would not reach up to 50,000 CUP and probably behave like a "hot" 54R round.


After looking at MidwayUSA's barrel selection, the barrels start at $80. Not bad!


This has me all warm and squishy inside. :)
 
#5 ·
#8 ·
I totally agree about the G3 mags! Since I have so many left, they are my first choice. Those Bren mags look interesting, so I may actually pick up a few of those.


Check this out - the current Hodgdon data indicates 50,000 CUP is the *MAX* for the hottest of loads which are intended for the modern firearms. Obvoiusly these wouldn't work in a lesser rifle. The important thing to me is the comparitive data for 7.62x54R. The asterisks show the hottest load on their charts. I copied only the hotest of loads - more are listed on their site.

Curious that they list the x54R as a .308 "class" bullet. Somewhere I read a post that x54R can climb up to 49,000 CUP. Presumably that's with a hot military surplus load.

Cartridge: 7.62 x 54R

Bullet Weight (Gr.) | Order BW | Powder | Bullet Diam. | C.O.L. | Start Grs. | Vel. (ft/s) | Pressure | Max Grs. | Vel. (ft/s) | Pressure

150 GR. NOS BT | 150 | H4895 | .308" | 2.875" | 46.0 | 2769 | 38,000 CUP | 49.5C | 2938 | 46,300 CUP

200 GR. SPR SP | 200 | H380 | .308" | 2.950" | 46.0 | 2337 | 41,200 CUP | 49.0 | 2432 | 46,600 CUP*
220 GR. HDY JRN | 220 | H4895 | .308" | 2.830" | 38.0 | 2143 | 41,200 CUP | 41.0 | 2263 | 46,600 CUP*


Cartridge: 45-70 Government (Modern Rifles Only)

Bullet Weight (Gr.)| Order BW | Powder | Bullet Diam. | C.O.L. | Start Grs. | Vel. (ft/s) | Pressure | Max Grs. | Vel. (ft/s) | Pressure

300 GR. SIE HP | 300 | H4198 | .458" | 2.525" | 59.5 | 2394 | 37,300 CUP | 63.0 | 2532 | 50,000 CUP*
350 GR. HDY JRN | 350 | H4198 | .458" | 2.540" | 50.5 | 2104 | 35,100 CUP | 56.0 | 2300 | 50,000 CUP*


Cartridge: 45-70 Government (Lever Actions)*

Bullet Weight (Gr.) | Order BW Powder | Bullet Diam. | C.O.L. | Start Grs. | Vel. (ft/s) | Pressure | Max Grs. | Vel. (ft/s) Pressure


400 GR. SPR JFP | 400 | H335 | .458" | 2.540" | 52.0 | 1798 | 25,400 CUP | 58.0 | 1995 | 40,000 CUP*
400 GR. SPR JFP | 400 | Benchmark | .458" | 2.540" | 55.0 | 1856 | 29,600 CUP | 58.5C | 1986 | 40,000 CUP*
 
#11 ·
The .444 marlin was originally made from untrimmed 30.06 brass in development by Remington.The rim was left untrimmed for .444 & trimmed for 30.06. The first .444 cases were headstamped 30.06 Remington. Hope this may help.
That is interesting as it would make finding cheap brass possable for a rebated 444 marlin build.although it would have to be straightend out.

tromix has already built a 444 marlin on a 410 sagia all ready. the chamber pressures between the 45-70 and 444Marlin are very simular when loaded with smokeless powderThe 444 is loaded to around44.000 CUP. I under stand that he actually is taking orders for them. Even though the 410 does not make that kind of pressure dosent mean the gun (IE BOLT AND TRUNION) wont handel it. the trunion is pretty much the same. I dont think a 45-70 will fit in a sagia Mag as it is the round is aproximently .100 larger in diamiter.(I could be wrong).

What is the current cost of a psl kit?? trying to figure what the total build cost would be.
A 45-70 would certanly be impressive aswell as severl others that are simular .458x2, 450 Marlin(basicaly a 45-70 but designed to handel hotter loads and not chamber in the weaker 45-70,s),450 Alaskan there is also a 45-60 that is starting to make a come back. that may be even better on a AK platform case is 1.89 long
 
#13 ·
(SLAPS FOREHEAD) I should have read that more closely! $30 each just stinks. However if I could get that to work with my SVU clone.... HRM....


Here's what I decided today - I am going to use a PSL bolt and whatever trunion I can find. Presumably a Yugo trunion, because I don't think there are any PSL trunions available. Those two parts together will be about $160 or so. That $80 barrel from MidwayUSA looks promising, unless there are cheaper ones to be had. I can't find any of the T/C barrels for less than $250. So the way I see it:

Bolt & carrier - $150
Barrel - $80
Trunion - $25 ???
Coldsteel 1.6mm blank $40

I think I have enough parts in my pile to handle the rest. And I'll machine the piston and the gas tube. If I build the muzzle brake, that will cover all of the parts except the furniture.

For the furniture, I'm thinking I'd like to put a PSL-style skeleton stock on it, but I'm not sure. I'll have to think about that some more. Maybe I'll make the buttstock and handguards too :D I need to look at some of the AK variants to see how I want to fix it up.

My estimate is starting around $300-400 for the entire build. Assuming I use the pile G3 mags like I did with the SVU. ;)


ETA - didn't think about it until just now... Numrich has 45-70 replacement Marlin barrels for $46. They have dovetails on them, and appear to screw into the breech. Does anyone know if they fully support the base of the cartridge? Or do they have a shimmed arrangement? It looks like there's a little spar or something on the chamber side, which is why I ask.
 
#15 ·
#18 ·
HRM I didn't realize the extractor fit INTO the barrel on that one. Perhaps that $80 job from Midway would be better?

Here's my thinking - look at the 7.62x54R breech. The bolt grabs the rim. The barrel supports the case all the way up to the base (and obviously this is how headpace is set).

It sounds like that Marlin barrel would not support the chamber wall with an AK extractor. It sounds more like a shotgun action.

I'll have to look more closely at that exploded view of the Marlin... I'd hate to buy a barrel that doesn't work.
 
#19 ·
After looking at my dad's Marlin barrel setup, I think it will be less hassle to use the $80 blank. No sleeving required and no grooves to fill in.

I picked up a box of ammo yesterday. The G3 magazine won't work due to the follower tipping too much. Ditto for the FAL magazine. A new follower will be necessary for either magazine to work. And only steel - the alloy G3 mags bulged WAY too much when I loaded it! With the spring fully compressed, I could only get 9 rounds, and that was pushing it. 10 rounds and the spring is too tight to let them feed.

I need a magazine more like a Siaga .410, CETME, or SVD/PSL magazine than a straight-boxed G3. The rim needs the curve, but not as much as an AK curve. I curved magazine may work without any special follower, however I'm thinking an SVD/PSL style follower that has the raised side all the way front-to-back will be a necessity.
 
#21 ·
I don't know, but I am not resizing the 45-70 brass from anything, I'm just buying factory brass. I'm considering an MG13 magazine or perhaps a Bren or CETME. A new follower is almost certainly going to be needed...
 
#23 ·
but (>>>>turning blue in the face<<<<) the 45 win mag is not .458" its .451" same as 45-70 same as 45 acp...[
QUOTE][/QUOTE]

Im pretty sure the 45-70 uses a .458 rifle bullet not a .451 bullet. at least all the books I have show it that way. Im I missing something???

HC some were I read that a 410 sagia mag will NOT work with 45-70 and that a 20 guage sagia was a better fit. I will try to find that link. I have a 3" 410 sagia if I can find some 45-70 ammo I will try to check it out.
I am followning along on this 45-70 build. were are the bolts avaliable for this build??????????
Iwill try to keep the 444 marlin stuff to the other link.
 
#24 ·
Why not just use that .458 barrel for a .458 SOCOM? :D :D :D


According to Hornady, the 45 Wincheseter Magnum is "essentially an elongated 45 Automatic." It uses .451 bullets, not .458. Hornady's reloading suggestions are for the 200 gr, 250 gr, and 300 gr bullets.

.45-70 uses .458" bullets. Again, according to Hornady #7.





Now, about that magazine...

I looked very closely at an M-14 magazine today at the gun show. No dice. The rear section is open (where the BHO activator sits) and the .45-70 rim would have issues with that. I think the MG-13 magazine is the same, not really sure. I'm still leaning toward Bren magazines, or G3/FAL mags with a new follower. This is going to need a new follower no matter what. The normal followers for the bottleneck cartridge design cause the straight-wall rounds of the .45-70 to tip the follower and cause feeding issues.



Bolts - I'm going to use a PSL rimmed bolt and trunion, and open up the bolt to .602" for the .45-70 rim. According to Hodgdon, the 7.62x54R CUP pressure is 46k, the MAXIMUM heaviest pressure I can find for .45-70 is 50k. 4,000 CUP difference. That is right on the line and I doubt I'd use that particular load. The other loads are right in the 40k range, so I should be OK as far as safety is concerned. I'm surprised to see the highest pressure is with a 350gr bullet, and the 500 grain bullet is less pressure. 500 grains! :D
 
#25 ·
Here are a couple comparison pics between the FAL, G3, and Bren mags. I have my Romak 3 stuff buried right now, but I think I posted another pic somewhere. I'll see what I can dig up...

FAL, G3, and Bren mags:






Comparison of width and length of feed lip area:



Notice the HUGE rib on the back of the Bren, and the BHO lug that lives there. These would have to be deleted from both pieces. I think you could just cut the rib off and braze/solder/weld a new strip on the back. The follower could just be ground/milled off. Aside from the rib, the width and length of the .303 Bren mag is similar to the .308 mags.

Look at the stampings in the sides of the FAL and the tabs and dimples at the top of the G3 mags. These mags weren't designed for a rimmed case, and I think these areas might cause problems when feeding the case. The Bren mag was designed for a rimmed case.




These next 2 pics are just to show the front and back of the Bren feed lip area.







And one final pic with the case dimensions and OAL measurements from Ammoguice.com

 
#26 ·
I do have some doubts about the Bren mag...

With the shape and size of the 45-70, I think there might be an issue with how many rounds you can get into the Bren mag.

The 45-70 has a larger base diameter and isn't tapered like the .303. The rounds won't follow the same curve when packed into the mag, so capacity could be seriously diminished.

The size of the case head will also limit how the rounds can stack into the mag.

I might draw up some 45-70 cases in Visio and see how much they curve when stacked together.


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