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Shooting & Reloading - Mausers, Big Bores and others >> Big Bore Rifles
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leeenfield
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Reged: 07/12/11
Posts: 53
Loc: Canada
The 375-303
      #202378 - 13/02/12 12:56 PM

I'm considering re-boring my BSA Lee Enfield N01 to 375 and I have a number of questions that I'd like some help with.

First, has anyone re-bored a LE barrel to 375 and how has it worked out? The muzzle on my 25" cut down original barrel is .668" and I wonder if there is enough meat for a 375 re-bore.

Second, what length does .303 brass turn out to be after fire-forming in a 375-303 chamber?

Third, what cast bullets do 375-303 users tend to favour and with what twists of rifling?

Thanks for your help as I gather more information.

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tinker
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Reged: 12/03/05
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Re: The 375-303 [Re: leeenfield]
      #202389 - 13/02/12 03:09 PM

Muzzle of the Lee-Speed .375 is .655"dia

I don't know what the minimum outside dia would be for your rebore project.
You need to call a barrel maker, and/or get references for someone to do the rebore. They will be able to tell you minimum wall thickness for your barrel at muzzle, but I bet you'll be just fine!


I think weight and balance will be the biggest factors.





Cheers
Tinker

--------------------
--Self-Appointed Colonel, DRSS--



"It IS a dangerous game, and so named for a reason, and you can't play from the keyboard. " --Some Old Texan...

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DarylS
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Reged: 10/08/05
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Re: The 375-303 [Re: tinker]
      #202441 - 14/02/12 03:47 AM

As for bullets and loads, Ken Waters made up a .375/.303 on a Ruger- almost straight taper on the case IIRC. His data looked to be soft, and probably OK for the Enfield is worked up from below - carefully, as is normal handloading practise, which everyone knows and many people don't do - some get pay the piper with injuries.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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leeenfield
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Re: The 375-303 [Re: DarylS]
      #202443 - 14/02/12 04:45 AM

Thanks to all of you for your ideas. I think that I have determined that the .668 muzzle will be fine for a re-bore. That leaves me with choosing a bullet so that I can get the throating and rifling twist right. The bullet will be partly determined by the overall length of the loaded round which will have to feed through a Lee-Enfield magazine. At the moment I'm investigating the Lyman378674 mould at 335 gr or the 264 gr #375449.

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JFE
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Reged: 03/06/07
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Re: The 375-303 [Re: leeenfield]
      #202480 - 14/02/12 03:43 PM

I use cast in a few 375 cal rifles and all have 12" twists. The moulds I use cast bullets in the range 250-300 gr and all work well in this twist. Most factory moulds are designed for use in a 38/55 and have crimp grooves located accordingly. These may not be ideally located for your application, depending on the throating.

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leeenfield
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Re: The 375-303 [Re: JFE]
      #202510 - 15/02/12 02:38 AM

Thanks, JFE. This is helpful. I wonder if you would share some of your 375 load data with me? Also if your 375s are 375-303s do you fire-form or cold form your brass? I'd like to know what the case length ends up being after forming. All of these questions are because I'd like to give my barrel maker as much data as possible so that he can do the neck and throat to suit the bullet I choose and the overall loaded length. It's kind of like a chicken and egg situation -- I'd like to give hime a loaded round as a reference but I have no way of producing one at the moment. I think I will focus on the Lyman 375499 as a bullet choice. I also have a 255gr plain base Lyman for my 38-55 and I can play around with both. I know these are a lot of questions so many thanks indeed.

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DarylS
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Re: The 375-303 [Re: leeenfield]
      #202512 - 15/02/12 04:08 AM

Either the .374449 Lyman or the RBCS .375, 250gr. bullet will work fine. The RCBS bullet has been a good shooting bullet for me, in 3, .375's. The #375449 also shot well in my BRNO .375H&H back in the 70's. I ran the RCBS bullet to 2,800fps (hardened & W/LBT Blue) in a .375H&H and still held onto 1 1/2" at 100 meters.

For a jacketed all-round bullet in that small capacity case, I'd go with the 225gr. Hornady. Deer, mose, elk bear- whatever. You should be able to hit 2,350fps to 2,450fps with it.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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JFE
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Re: The 375-303 [Re: leeenfield]
      #202578 - 15/02/12 10:18 PM

Here's a couple of threads you might like to read:

http://forums.nitroexpress.com/showflat.php?Cat=0&Number=95857&an=0&page=0#Post95857

http://www.castboolits.gunloads.com/showthread.php?t=63406&highlight=375%2F303

http://www.castboolits.gunloads.com/showthread.php?t=20340&highlight=375%2F303

It might be worthwhile tracking down some of the posters for more info. I dont have any experience with 303 wildcats but a lot of users that do seem to complain about feeding problems, or can only get them to feed with a certain bullet etc etc.

I load for a 375 Win, 375 H&H and a wildcat 375/356 and all have 12" twists. With all of them, as long as you use the right alloy, lube and the cast bullet fits the throating well, you can achieve speeds of 2000 fps or more with good accuracy.

I sometimes form cases for the 375 Win from 30/30 brass and usually get about 1mm of brass shrinkage.

As far as forming brass is concerned, if the brass is new and unfired I generally just open up the necks. However if the brass is old and/or has been fired before, I anneal the neck and shoulder first and this minimises split necks and/or shoulders. I tend to simply load the formed brass with close to a full load and top it off with a cast pill. This way instead of firing confetti, flour or whatever in the air to fireform the cases, I have useable rounds to use for plinking or hunting.

Regards the throating to use, I think you need to look at whatever jacketed pills you want to use and try to have a shallow throat if possible if you want to use cast bullets (and factory moulds). As well as the bullet Daryl suggested, I'd suggest a 235gr Speer as it should feed well and they perform pretty well.

Cast bullets normally don't do very well in long unsupported throats. Ideally the throat for a cast bullet should be just long and wide enough to accommodate the front driving band.

Hope I havent confused you too much.

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leeenfield
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Re: The 375-303 [Re: JFE]
      #202586 - 16/02/12 12:22 AM

Again, more good information . Thanks. As JFE mentions, the magazine feeding will be an issue to deal with. There are many posts that talk about the .375 feeding from a LE magazine with no problems, but unless the original Lee Speeds had a special mag for the .375, some magazine modification will be necessary and I am not sure at this point how successful they will be. As an experiment, since I have no 375-303 rounds to play with, I seated some 255gr Lymans very shallowly in some 38-55 cases (close, but not the same as the 375) and it is obvious that there will be issues with a straight-sided case. It looks as though modifications might be possible but it will require further tinkering to find out. I've looked for posts about modifying LE mags for this purpose, but no success yet. Cheers.

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DarylS
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Re: The 375-303 [Re: leeenfield]
      #202606 - 16/02/12 05:16 AM

You should be able to use your .38/55 expander die for to enlarge a .303 case to accept the 255gr. bullet, you'll be able to use a .375/.303 ctg. for feeding. You may have to taper it's nose slightly, is all, to fit the .303 case neck. This is all I did to several sizes of expander plugs for straight cases.

I've necked .303 brass all the way up to .416 cal., .32, .35, .375 and .416 merely using expander buttons in a single expander die from my .375 Winchester die set.

As a side note, I actually use only .38/55 dies (3 die set - green box) for my .375Win., as .375 Winchester dies weren't available when I bought the Winchester rifle for my wife - back in 77 or 78 - whichever year it was.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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Story
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Reged: 15/10/08
Posts: 262
Loc: SE PA, USA
Re: The 375-303 [Re: leeenfield]
      #213808 - 01/08/12 12:40 AM

Quote:

I'm considering re-boring my BSA Lee Enfield N01



So what did you wind up doing?

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Tom30887
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Reged: 01/07/12
Posts: 78
Loc: QLD
Re: The 375-303 [Re: Story]
      #213838 - 01/08/12 07:06 AM

Check too see if You can get it re bored mate. A 303 could be taken out to 375 but often it's just as expencive and sometimes more expencive to re bore then to just by a new barrel. After all it has to be re drilled, re reamed, re buttoned/cut, and re lapped and then it's best to remove the first and last two inches after lapping.

Tom.

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DarylS
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Re: The 375-303 [Re: Tom30887]
      #213853 - 01/08/12 10:43 AM

Reboring & rifling here, I'm told is about the price of a new barrel blank - around $300.00. So in the long run, re-boring and rifling would be cheaper, unless one has his own reamer and does his own threading and chambering - my only saving grace on re-barreling.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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