| Carpetsahib |
| (.333 member) |
| 15/08/17 08:15 AM |
M-S 1903 Rebore
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I have a 1903 by Army and Navy that shoots pretty well, but has a faded and heavily worn bore. The groove diameter is approximately .268; I haven't measured the bore, but I assume it is around .262 or so. Anyhow, I am thinking about re-boring and rifling to .277, and make a 6.8/6.5x54 wildcat. This would be somewhat similar to the 6.8 Chinese cartridge, but based on a smaller diameter case.
The object of this exercise is to (hopefully) achieve a cartridge that will feed without magazine modifications. Any suggestions?
| MikeRowe |
| (.333 member) |
| 15/08/17 08:34 AM |
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Re: M-S 1903 Rebore
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You may have to go a little bigger than .277.
I think the reborers like at least two calibers larger so the reamer will bite correctly
and make a true bore.
A 7mm would be good.
| Carpetsahib |
| (.333 member) |
| 15/08/17 09:52 AM |
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Re: M-S 1903 Rebore
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7mm was actually my first choice. Perhaps that slightly larger bullet will still feed through the stock magazine. I'll mock-up a cartridge and give it a try.
| 93x64mm |
| (.416 member) |
| 15/08/17 05:58 PM |
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Re: M-S 1903 Rebore
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Too many choices Carpetsahib, might come down to what will work through you magazine!
6.5x54mm - 76mm OAL
7x57mm - 78mm OAL
7x54mm Lapua (6.5x55 base) - says 67mm OAL, I'd more believe closer to 80mm OAL!
7.5x55 Swiss - 78 OAL
https://en.wikipedia.org/wiki/7%C3%9754mm_Finnish
| Carpetsahib |
| (.333 member) |
| 15/08/17 09:35 PM |
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Re: M-S 1903 Rebore
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Quote:Finding something that will work through the magazine is precisely my concern. I want to find the smallest bore diameter that will allow a clean re-bore and re-rifle. Then that bullet will be fitted to the 6.5x54 case to form a new cartridge - keeping all dimensions identical with the original with the exception of the bullet diameter.
Too many choices Carpetsahib, might come down to what will work through you magazine!
6.5x54mm - 76mm OAL
7x57mm - 78mm OAL
7x54mm Lapua (6.5x55 base) - says 67mm OAL, I'd more believe closer to 80mm OAL!
7.5x55 Swiss - 78 OAL
https://en.wikipedia.org/wiki/7%C3%9754mm_Finnish
With that in mind, I plan to mock-up a couple of cartridges: one with the 140 gr. .277 bullet, and one with a 140 gr. .284 bullet. If the dummy cartridges can be inserted into the magazine, then I will know if I am on the right track.
| Igorrock |
| (.400 member) |
| 15/08/17 11:51 PM |
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Re: M-S 1903 Rebore
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Quote:
7x54mm Lapua (6.5x55 base) - says 67mm OAL, I'd more believe closer to 80mm OAL!
There is a reason why itīs so short. Most finnish factory loads used to have very light, only 5,1 g weight bullet. Most of those 7x54 caliber rifles have so low barrel twist that the heaviest acceptable bullet is 10,1 g and itīs shape should be like cylinder with round nose. I have itīs "cousin" i.e. 7x53R and it has very same "problem".
| Vladymere |
| (.300 member) |
| 16/08/17 11:53 AM |
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Re: M-S 1903 Rebore
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Why not slug the bore and see what you have? Knowing what you have might lead you to a billet that will function well.
My MS-1903, that I have not developed loads for slugs out at .269" grooves, .256" lands and a fired brass neck I.D. of .271". I hope this is of help.
Vlad
| Carpetsahib |
| (.333 member) |
| 16/08/17 01:12 PM |
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Re: M-S 1903 Rebore
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Quote:Yes, I plan to slug the bore, probably this week. My initial post was probably premature, but I wanted to see if what I have in mind seems feasible.
Why not slug the bore and see what you have? Knowing what you have might lead you to a billet that will function well.
My MS-1903, that I have not developed loads for slugs out at .269" grooves, .256" lands and a fired brass neck I.D. of .271". I hope this is of help.
Vlad
| 2152hq |
| (.300 member) |
| 16/08/17 01:46 PM |
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Re: M-S 1903 Rebore
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I have a 256 Gibbs Magnum cal M/S built on a 1903 Greek by Geo Gibbs.
I think the rotary mag is a replacement and a standard 6.5 M/S caliber.
It would not take and feed the 256 Gibbs Mag, which is a .470d base cartridge x 54mm.
I make my cartridges from shortened 8x57 brass. When each cartridge sits in it's slot in the rotary 6.5 magazine the extra dia makes it sit up high on the edges of the machined cut.
But dispite that, they feed and function just fine. No alterations to the rifles feed rails were necessary.
I did have to open the magazines cartridge guide ring at the front of the rotary mag a bit to allow the 160 gr bullets I wanted to use to fit and run around the rotary mechanism w/o interference. With out doing that , the bullet(s) would tip each cartridge upwards a bit as they jammed themselves underneath the guide. That brought the back end of the case upwards and caused difficult feeding and jamming.
The cartridge guide ring is removeable from the mag assembly but more easily worked on when still assembled.
I could have reduced the amt of mtr'l I removed from the guide ring by seating the bullet deeper. That would place the ogive back further and more clearance would be given. Using lighter weight bulelts would be the very simple way to do it and may very well be the answer to little or no alteration with spire points (if they feed well in the M/S!).
What this all means is that a conversion using the orig 6.5 magazine with little or no work to the magazine itself and no alteration to the actions feed rails is a very good possibility if the right cartridge is chosen.
I would be thinking of a 7mm on the orig 6.5M/S first, That would perhaps require a slight increase in dia of the neck portion of the rotary mag feed troughs.
Next would be something like a 7mm on a 54mm .470d base case.
Just my thoughts
| Grenadier |
| (.375 member) |
| 16/08/17 11:16 PM |
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Re: M-S 1903 Rebore
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If .277 would work that would be good but it might be better to get it rebarreled. The current contour could be duplicated and the sights moved to the new barrel.
| Carpetsahib |
| (.333 member) |
| 17/08/17 08:28 AM |
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Re: M-S 1903 Rebore
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Quote:Rebarreling is an expensive option. I didn't mention that this is a takedown rifle. I would much prefer a .270, if the old bore will clean up during reaming.
If .277 would work that would be good but it might be better to get it rebarreled. The current contour could be duplicated and the sights moved to the new barrel.