Will a 7.62x54R reamer clean up a .308 chamber?

[scythefwd]

First, will a 7.62x54R reamer clean up a .308 win chamber? In other words, is it possible to rechamber a .308 win to 7.62x54R?

Second, due to the differences in pressure, the x54R being close to 52k psi while the .308 is 62k psi, will this most likely be safe in a break action rifle? Just looking to have something a bit obscure to play with.

 

[Cosmoline]

They are utterly different cartridges. All dimensions are different, and the 54R is rimmed so you will have major feeding issues on top of everything else.

 

[scythefwd]

Cosmoline, I understand they are different cartridges. I am thinking of having a .308 barrel rechambered. If the x54R is larger in all aspects, then should be able to do the rechamber safely without worrying about a false shoulder like what would happen with a .30-06 to .300 wm rechamber. It is a single shot rifle, so feeding shouldn't be an issue... no harder than any other round.

I don't see any issues with pressure due to the .308 being a considerably higher pressure round.

 

[fguffey]

from the stand point of cleaning up the chamber, no, the 7.62x54R case diameter in from to the rim is .485, the case head of the 308 is .470, that is .015 thousands difference., The case length for the 7.65 is close to .100 thousands longer but the shoulder is about the same diameter, the length of the case from the case head to the shoulder is about the same 1.560



F. Guffey

 

[scythefwd]

fguffy -
Where do you think the chamber would be out of spec? From your numbers, it looks like it would rechamber well, but I admit ignorance in this area which is why I am posting here.

 

[fguffey]

going to 7.62mm34R, I had to read that again, the 'in other words'.

The 7.62 reamer will clean up the 308 chamber but the thickness of the rim is outside the chamber, without doing the numbers I believe the barrel will require setting back because of the distance from the head of the case to the shoulder is the same on both, again the rim on the Russian is not included.

Sorry about that,

F. Guffey

 

[scythefwd]

what do you mean by setting back? Couldn't the smith just run the chamber reamer in further and then inlet the breech face to allow for the rim to sit flush? I would have to have a new extractor built, but that isn't that hard I might even be able to modify the current extractor to just sit under the rim since it won't have to slip into the groove anymore.

 

[Clipper]

I don't think he's paying attention, and missed 'break-open single shot'. A competent smith, or even a talented amateur should be able to pull it off (the extractor modification). The .003 tighter bore may or may not be problematic if shooting milsurp, but I think Norma uses .308 bullets in it's factory rounds, and worst-to-worst, you could stick to reloadable brass like Wolf, and just pull and swap bullets, though I doubt the .308 barrel is gonna be tight enough to cause pressure problems.

I was going to have my buddy get a replacement barrel for his NEF .17HMR, so I could rechamber it to .17 Rem Fireball for my centerfire Handi Rifle...That was going to require a bit of ingenuity for the extractor, but we're both retired Toolmakers, so it was within the realm of our experience.

 

[fguffey]

scythefwd, the rim is .063 thousands thick, I have 62 chamber reamers, the only reamers that cut a countersink are reamers for belted chambers. The face of the barrel could be cut and the rim could be to allowed to countersunk into the face of the barrel, this would allow the rim to get out of the way when the brake over closed and also allow the reamer to move forward to clean up the chamber.

The 308/311 could be worked out with a 308 neck sizer ball in the full length sizer.

It would be suggested the first measurement maid would be the head space on the rifle to be chambered, This would allow the smith/novice to determine case head protrusion or Clarence between the case head and breach face.

F. Guffey

 

[fguffey]

head space would be determined by the depth of the counter bore,

F. Guffey

 

[scythefwd]

fguffy - the frame/barrel gap is smaller than my smallest feeler gauge which is .04mm. I cannot see any gap, but a .001-.002" gap could be there. Counter sinking the rim to be flush with the breech face should work just fine.

That said, pressures aren't going to be an issue is it? So far we have just discussed mechanical issues, and I have stated I don't think pressure will be an issue. Any agreement or disagreement on that thought?

 

[fguffey]

The 7.62mm54R is an old cartridge, like the 30/40 Krag, the bolt face is dished to accommodates the bevel on the head of the case, the bevel would reduce the contact between the breach and case head.

The 7.62mm54R is tapered like the 303, 30/40 krag and 30/30 Winchester, cases that are not know for high pressure, the 308 W has little trouble keeping up with the 30/06 because of the powder column, it is shorter and larger in diameter than the powder column of the 30/06 and is considered a high pressure cartridge, unless the shoulder is improved and or the taper of the case is removed by increasing the diameter of the case to that of the diameter of the case head, the chamber will not be considered 'high pressure', and of course that being said, I can not protect someone from them self..

The feeler gage is a foreign tool to the smith and reloader, if I had the chance to set head space on a chamber by controlling the depth of the counter bore by measuring case head protrusion I would do just that and leave the go, no and beyond gages to those that like to be surroounded with tools.

F. Guffey

 

[Zeke/PA]

Before I would attempt this "conversion" I would CAREFULLY research the differences in Bore/Groove in the Russian stuff versus what is compretively tollerable in the NATO round.

 

[hillbillydelux]

Is it possible to rechamber a .308 win to 7.62x54R?

Ok I gotta ask. Why? Unless you happned to stumble across a couple thousand rounds of free 7.62x54R rounds. Im just curious thats all.

 

[Cosmoline]

I misunderstood what you were aiming for.

As to the .308 issue, that's an easy fix. You just load .308 bullets as you would with the 7.62x53R Finnish variant. And avoid standard ammo or surplus.

 

[7.62 Nato]

The Ruger Mini 30 runs a 7.62 x 39 (311 dia.) through a .308 bore.

 

[sonier]

mini 30 has a like forcing cone that resizes the .311 through a .308 bore but yes ive heard of people shooting .311 in .308 bores without any issues

 

[7.62 Nato]

I wondered how they did it. I just heard of it recently.

 

[scythefwd]

.311 in a .308 will increase the wear on my bore, but it does work. There are 7.62x54R manufacturers that make it in .308 I believe.... Norma is one I have heard.

hillbillydelux- huge fan of that cd... anyways because I think it would be different. I always wanted a loud range toy I was just planning on getting a spare .308 barrel for the gun and doing the rechamber... it is just as cheap as getting a custom made.

Zeke - I am aware of the .312 / .308 issue. It increases throat and bore wear but can be done. It just "shoots out" your barrel quicker. I only plan on running maybe 100 or so rounds of the .312 stuff through before it gets reloaded with .308 diameter bullets.

 

[scythefwd]

fguffy - feeler gauges are for those who work other trades. Machinists use them to check tolerances. On a bolt gun, you can get away without knowing the gap because the bolt moves up to meet the chamber. On a break action, where there can be a gap between breech face and the end of the chamber and you don't want the breech face in contact with the round until it achieves full lock knowing exactly how wide that gap is becomes a little more important. Setting back a barrel on a break action involves a little more than just cutting new threads and shaving off a couple thousandths on a break action. You have to break off the barrel lug and re-weld it. This can create a gap that HAS to taken into account when head spacing.

Hillbilly - The whole plan is to take the barrel down to about 17 inches, re chamber, and have Mike Bellm put in one of his integrate muzzle brakes. They are drilled into the barrel, so nothing hanging off the end. Even if they just work as ports it could still be fun to play with. I always wanted something loud, and this is about the loudest round I could use on this frame If I get really bored, I'll put a bipod on it and scope it. Kinda make a "tatical" single shot just for the "*** were you thinking" looks I'll get It's always fun to mess with peoples preconceived notions and this gun I think could do it if it shoots well.

 

[navyretired 1]

I've never seen so much written about such an easy answer. Yes you can ream a .308 Win chamber to 7.62X54R and clean up the whole chamber. The tapered rim doesn't amount to anything as outside of rim is not under any pressure.
For the feeler gage guy's, how do you think you measure a shotgun (single or doubles) fence to see if they are off their face (Answer 0.001 to 0.0015" feeler gage) and we're talking about a single shot rifle.
The counter-bore goes in the barrel not the breach face.
WHY??

 

[fguffey]

Navyretired 1,

"scythefwd, the rim is .063 thousands thick, I have 62 chamber reamers, the only reamers that cut a countersink are reamers for belted chambers. The face of the barrel could be cut and the rim could be to allowed to countersunk into the face of the barrel, this would allow the rim to get out of the way when the brake over closed and also allow the reamer to move forward to clean up the chamber"

"head space would be determined by the depth of the counter bore"

I will never get to the point I believe I am too good to use a feeler gage, the companion tool to the press.

Scythefwd, to have said nothing would have shown a little class and been OK, A 'Thank You' would have have shown class.

F. Guffey

 

[fguffey]

"but I admit ignorance in this area which is why I am posting here"

F. Guffey

 

[Cosmoline]

I only plan on running maybe 100 or so rounds of the .312 stuff through before it gets reloaded with .308 diameter bullets.

It's gonna leave a mess to clean up. Why not just load .308" rounds? If you want to be precise about it, Lee sells expander decapper rods for a few bucks that will give you the right size to fit the standard bullets. Just give them a ring. You should be able to get some phenomenal accuracy from this barrel in .308" with the wide array of match bullets available.

For safety just make sure you have enough steel left around the chamber after the reaming.

 

[scythefwd]

Fguffy, When it comes to reaming out chambers, I am very ignorant. Handloading on the other hand I have a little more experience. I have already started my education on hand loading for break actions, which most everyone in the reloading forum agree is a different beast due to frame/barrel gap. I generally don't thank people for info till the end of the conversation and I had a feeling that this conversation wasn't over.

Cosmoline - Do you know a good source for boxer primed brass? The stuff I am seeing is almost as expensive has loaded ammo around here. IF I can find the .308 loaded brass.... I'll go with that like you suggested, but if I can't I will have to either empty some brass or find some. I have a friend who has a MN, so we might be in for a fun day if I get this barrel made. I was just going to shoot some of the .312 stuff to get the brass to work with.

Looks like just about every angle of this conversion has been covered, thanks for the conversation. Any other heads ups, gotchas, etc.. will be appreciated. Thanks again.