Has anyone done this? I have heard P 14s were converted to 300 win mag but has anyone gone the other way? I was messing around with my push feed Winchester model 70 in 300 win mag and a 303 british snap cap feeds great from the internal magazine. The rim of the 303 cartridge also fits nicely into the bolts face and extractor. Is this possible?
Rebarrelling a 300 win mag to .303 british
- Thread starter windy
- Start date
"...Is this possible?..." Anything is possible with enough time and/or money. In this case, it'd be money. You'd have to find a barrel. And a .311" barrel for a Win M70 will be a completely cu$tom made barrel. Then a smithy who has a set of .303 Brit headspace guages. Those can be rented though. If the smithy decides he has to buy 'em, you'll be paying for 'em and you won't get to keep 'em.
"...cartridge also fits..." Rim is 8 thou bigger.
"...cartridge also fits..." Rim is 8 thou bigger.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
No reason the barrel needs to be .311. A standard .308 barrel, using an appropriately sized reamer will suffice. Better bullet selection too.
unless you are using factory ammo then you will be firing a .311 dia bullet down a .308 dia barrel. that is going to jack pressures up and squish the bullet a fair ammount. if you are reloading for it. sure go ahead and put a .308 barrel on. but if you are shooting surplus and factory you may want to stick with the .311 barrel.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
You logic is fair but your facts are wrong. As long as your chamber has a sufficient throat diameter and leade angle, you will not see any difference in pressure (given same bullet weight/style and same powder load). PO Ackley ran tests to prove this, and I shall dig up the article when I can find it.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
...And he would need a new barrel if he wanted to rebarrel, right? Sunray suggested he would need to source an uncommon .311 barrel, and I suggested he simply use a very common .308 barrel.
PO Ackley's test:
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Sounds like an interesting article. Can't read it though. Need to log in to the site.
Do you need a special reamer to produce the necessary throat to utilize the smaller bore? If so, that would be an added challenge sourcing.
Do you need a special reamer to produce the necessary throat to utilize the smaller bore? If so, that would be an added challenge sourcing.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
Oh, sorry about that. I'll re-do it so they're visible to all.
Ive got a P-14 with a decent .303 barrel I'd be willing to swap you for, though its in a sporter rifle it still has the front sight, and Id need to get someone with a barrel vise to pull it. Or maybe just swap actions if they are in similar condition.
PM me if your interested.
PM me if your interested.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
All you need is a .303 reamer with a .300 pilot, as opposed the standard .303. Most reamers have a relief behind the pilot; I have a .30 Luger reamer here and the pilot is .299. It has a a relief with fully ground and sharpened flutes behind it, measuring .293 diameter which then taper up into the throat/leade. Thus removing .003 of the diameter of the pilot would allow the chamber to be fully cut and leave a longer but still gentle throat/leade.
...And he would need a new barrel if he wanted to rebarrel, right? Sunray suggested he would need to source an uncommon .311 barrel, and I suggested he simply use a very common .308 barrel.
PO Ackley's test:
By that it looks like using an undersized barrel creates some very erratic velocities which would really #### up accuracy. So it might be best to find a .311 barrel. Call some gunsmiths and they should be able to source one.
You should explain that to Ruger. They may wish to know that, as they have been using undersize barrels on a fair run of their product line. Their use of .308 barrels for 7.62x39 in particular, but I have read of them using them for .303 Brit as well.
Pull the .311 sizer out of the dies, and put a .308 one in, factory ammo costs too much anyways. Or use a pilot that fits the .308 barrel on a .303B reamer and get on with the rest of yer life.
The experiences of them what done it seem to differ from them what formulated a theory.
Cheers
Trev
Thanks for all the info. I'm gonna start doing some research now that this sounds possible.. My goal is to have a winchester model 70 or a savage model 14 in 303 british. I definetly want a .311 barrel. Anyone who can recomend a gunsmith in alberta that may be of some help please let me know. Anymore advice would be appreciated.
Thanks.
Windy
Thanks.
Windy
i think the biggest problem you will have is getting the mag to feed the rimmed cartridges properly. mags are always the biggest problem with caliber changes that are outside the family. (ie, 308 to 243 or what have you) going from 300 WM to 303 is going to cause some feeding issues. rimmed shells have a weird tendency to flip up when being pushed as the feed lips press on the rim not the body of the shell.
