A friend has a fine Mauser in 7.65 Arg that has had the chamber bushed to convert it to fire 308 Win ammo. He wants to remove the bushing to fire the original round. How might this be safely done?
Bill,
That depends, sorry to be vague, on how the insert was put in. Some are pressed,some are soldiered (soft or silver) and some use an adhesive such as Black Max. Also I beleive the 7.65 Argentine is a longer cartridge than the .308 as well as the bullet diameter of the 7.65 is .313 and the 308 is well .308 so you would want to slug the barrel to see if if has been replaced. Finally you don't know how the bushing was inserted, did they bore the chamber out to a cylinder or make the bushing the same dimension as the 7.65 round. In other words you might remove the bushing and create a larger problem.
If the bore is the correct size for the 7.65 round it might be easier to recut the 7.65 chamber but you will want to check the dimension of both cartridges.
Its not mine but personally, if it shoots well, I would live with it. If it is not grouping well and the gun was not rebarreled a thought might be to try a slightly larger diameter bullet to see if that improves groups.
Good luck...
WBLDon
Is the recvr front ring of the action notched for the bullet point for loading from stripper clips?
Is the rear recvr ring stamped '30' ?
If so,,
A possibility is that the rifle may have been one that was orig in 7.65 Argentine Mauser and then converted to 30-06 in the 1950's by FN
That is the type I described in the first 2 lines. These used the orig 7.65 Argentine cal (.313) bbl. & just a rechamber to 30-06.
An ample supply of surplus WW2 ammo so they'd be our friends post WW2.
Perhaps someone has since used a chamber insert on one of these 30-06 chambered Argentine rifles to (further) convert to 308/7.62 NATO caliber.
Lots of 7.62 Nato surplus ammo around in the 80's, 90's and early 2000's.
If you remove that insert, you'll have a 30-06cal rifle with the orig .313 Argentine bbl spec.,,not a 7.65 Argentine chambered bbl.
The Argentine Mausers in their orig 7.65 Argentine MAuser caliber converted to 7.62 NATO (as I understand it) were rebbl'd to the NATO 7.62.
The 7,62 NATO is slightly larger in dia at the bottom of the shoulder and upper body than the Argentine round and of course a couple M/M shorter.
On some 7.65 Argentine chambered rifles you can actually force a NATO round into the chamber and with some force close the bolt and fire the round.
The NATO round is jammed against the sidewalls of the Argy chamber, so it is defacto headspaced in that it sits firmly against the bolt face.
Firing the round will fire form the brass to a 7.65 Argentine case but with a very short neck on it becasue of the too short Nato brass compared to the Argentine round.
The .308 Nato bullet flys down the ,313 Argentine bore with no issue so pressure is low. Accuracy can be anything with a .308 bullet in a .313 goove dia bbl.
Sometimes very good, othertimes not so good.
The NATO round being slightly larger would have needed a chamber clean up rechambering recut operation if an insert was used to avoid the above,,the slightly larger in dia NATO rd from refusing to chamber in the Argentine chamber.
Just some thoughts before you go digging in there.
Bill, your friend should "slug" his barrel first, to see what he has. If it is, indeed, a bushed barrel he may be better off buying a surplus original chambered barrel from SARCO or a similar dealer. Having had some experience with chamber bushings, I agree with both WBL Don and Kutter that you can open a pretty expensive "can of worms", unless you know more about the bushing.
Mike
The rifle in question is a 1909 Peruvian that is original in every respect except that it lacks a 1/4" of closing the bolt on a 7.65 round and chambers a 308 readily. The rifle's condition is excellent. My present theory is that a finish chamber reamer would cut the bushing out without harming the barrel internally or marring external finishes. Der Ami's point is well taken, but the value of the rifle depends on the barrel number matching the receiver number. My "solution" assumes the bushing is readily machinable..
I doubt the chamber is original dimensions but it could be. When fitting a new chamber sleeve it is far easier to turn a parallel insert and reamer the chamber the same than it is to fit it to the original taper of the chamber. Additionally without boring out the original chamber you will end up with a very thin sleeve. Just my opinion.
Bill,
I suggest you go back and read Kutter's discussion again, especially the part pointing out that the 308's shoulder diameter is larger than the 7.65's, so that part of a 308 chamber would have to be larger than an original 7.65 chamber. If it was arsenal re-barreled to 308, it is possible they numbered the barrel to the receiver and maybe re-worked the rear sight to match the trajectory of 308 ball ammo. It wouldn't cost much to slug the barrel to see if it is 308 or 312-313".
Mike
If there is an insert, that is not welded in,
Block the throat
Pour in Liquid Nitrogen
Remove the insert
Please wear safety shield, gloves and long sleeves
Sometimes you can use dry ice.
Good luck
Mike
I think Kutter is right about chamber diameter. To sleeve the entire chamber may be an option, but it doesn't sound very appealing. Dry ice and liquid nitrogen sound like fun. Thanks to all.
Curious if the rifle is the 1909 or 1935. Seemed a fair number of 09s were rebarreled with Liege proofed barrels, still in 7.65. Matching bolt number on 1909s is hard to find so if present perhaps worth getting back to 7.65x53. I like the 7.65 round but as a shooter I appreciate the convenience of 308. Good luck.
I mentioned it in my first post but it may be worth repeating.
Lots of military issue Peruvian Mausers in 7.65 Mauser caliber were simply rechambered on their orig 7.65 bbls to 30-06.
So the groove dia in these 30-06 conversions is .312
Conversions were done post WW2.
I've read it was done by the Peruvian Govt and also some say by FN for them. We supplied the ammo post war.
The bbls show their orig Belgian FN mfg proofs and other period mfg markings. If the bbl is orig to the rifle the serial number matches and most do.
The front recv'r ring is notched. This was done during the caliber conversion to allow smooth stripper clip loading of slightly long(er) GI 30-06 rounds into the mag box.
The rear bridge was generally hand stamped ' .30 ' to note the caliber conversion from the orig Mauser round.
The Peruvian crest remains on the top of the ring.
It could be one of these 7.65Mauser caliber conversions to 30-06 caliber that has since had a .7.62NATO insert put into it for convenience of ammo supply.
Those inserts were very common for M1 conversions to NATO cal at one time and 'the thing to do' with a crusty old 30-06 Military bolt rifle,,,who wants one of those after all.
If this is what you have,
Removing the NATO cal insert would leave you with a 30-06 chambered bbl with a .313 groove dia bore of the orig bbl.
I have one of these Peruvian Mauser conversions to 30-06 here now, in bbld action form. Wondering what direction to go with it. Perfect bore but a .312 of course.
FWIW, (Some of?) the Peruvian Mausers have the 'reversed' flag safety positions on the bolt as well.
FIRE position is the Safety laid over to the right side.
Kutter, Your comments are well taken but pertain, I think, to the 1935 Model. I should have said earlier the rifle in question is a 1909. CJF, Yes the bolt is matching which is the major factor in this project.
RMB any update on your efforts.
Enjoy the week
Mike
Mike, I think he's decided to have the chamber bushed again but this time over the length of the case body. When the work is done, I'll report the outcome.
Bill,
Based on bad experience with someone else's bushing job, I recommend the following two things be insured. Be sure the cartridge case neck extends past the joint, so that obturation keeps high pressure gasses out of the joint. The second is to pull the bush into the barrel with a rod threaded on both ends with nuts and washers to keep everything tight until the glue sets or the solder cools. Bushes, pins, dowels etc. are pretty bad to back out of holes while waiting for glue to set/solder to cool; whether due to taper, trapped air, pressure from expanding gas; movement must be guarded against.
Mike
Mike, That sounds like good advice. I'll pass it on.