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Re: Possible .303 conversions

Post by Gamerancher » 06 Sep 2016, 8:42 am

.303 blown out to a straight walled .40 cal case gives you the equivalent of the old .40-72 black powder round. So a forty cal re-barrel and you have a bolt-actioned BPCR. 400grain cast bullet @ 1200f/s, awesome!!! Just re-size your old .303 brass. :thumbsup:
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Re: Possible .303 conversions

Post by <<Genesis93>> » 06 Sep 2016, 9:15 am

I reckon you're on the right track with a 45 barrel.... I would go a pistol round, 45ACP has been done in the smellie, (maybe a semi-auto conversion was done??)

Or go a 460S&W, or 0.476 (480Ruger/475Linebaugh) or even a 500S&W..... most have similar rim diameter to 303...

but we know you're gonna go scatter gun route....
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Re: Possible .303 conversions

Post by TheDude » 06 Sep 2016, 11:09 am

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Re: Possible .303 conversions

Post by Gamerancher » 06 Sep 2016, 12:43 pm

Yeah, sorry, er, um, I f#%cked up. The round I was thinking of 40-60 Maynard. Can use .303 British brass. Anneal neck/shoulder, neck up to take .40 cal bullet and fire-form in chamber. Trim to uniform length, done.
Steve Garbe (U.S.A) used one in BPCR silhouette years ago. Good accurate cartridge with low recoil and good knock-down on 500m rams.
Don't know what you were looking to do with it Bentaz, but loaded to mild pressures with a 300gr cast bullet would be good medicine on pigs 'n such. :thumbsup:
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Re: Possible .303 conversions

Post by Gamerancher » 06 Sep 2016, 5:51 pm

Fair enough, no harm in dreamin'.
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Re: Possible .303 conversions

Post by Tank » 06 Sep 2016, 10:02 pm

Gamerancher wrote:Yeah, sorry, er, um, I f#%cked up. The round I was thinking of 40-60 Maynard. Can use .303 British brass. Anneal neck/shoulder, neck up to take .40 cal bullet and fire-form in chamber. Trim to uniform length, done.
Steve Garbe (U.S.A) used one in BPCR silhouette years ago. Good accurate cartridge with low recoil and good knock-down on 500m rams.
Don't know what you were looking to do with it Bentaz, but loaded to mild pressures with a 300gr cast bullet would be good medicine on pigs 'n such. :thumbsup:


Sounds like just the ticket!!
Would only require a little work on the mag (I'd think) for a great pig gun.
Was there a .375 wildcat based on the 303 Brit?
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Re: Possible .303 conversions

Post by Gamerancher » 06 Sep 2016, 10:36 pm

No mag mods needed if you keep same c.o.l. with flat nosed bullets.
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Re: Possible .303 conversions

Post by Tripod » 06 Sep 2016, 10:39 pm

Once you get up to 40cal the mags don't work.That's why the 410 conversions were single shot. 444 can be done but you need to radically modify the mag and 444 brass is unobtainium at the moment. 45-70 rim is too big.
303-35 and 303-375 are very do-able and on my to do list.
30-30 is an easy one and works through the mag.
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Re: Possible .303 conversions

Post by Tripod » 08 Sep 2016, 8:24 pm

bentaz wrote:What about 300BLK rimmed?
Or a .303 chamber cut into a .308 barrel then just neck size down to 308?

300blk rimmed may have feeding problems, The 303 with a .308 bore works a treat, I just spun the expander in my dies down 3 thou to suit the smaller projectile.
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Re: Possible .303 conversions

Post by <<Genesis93>> » 09 Sep 2016, 9:29 am

bentaz wrote:What about 300BLK rimmed?
Or a .303 chamber cut into a .308 barrel then just neck size down to 308?


So kinda like a Cadet? :lol:
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Re: Possible .303 conversions

Post by COLLECTOR 1 » 12 Sep 2016, 8:21 pm

Have used a 303/375..... Scary but fun. Easy conversation to....As for 30/303.... I currently run one on a number 4 action, works a treat. My favourite go to ute gun. Built it a while ago when 303 ammo, brass and projectiles were in short supply. I run 150gn 30 cal Hornady interlocks in it, and trust me what you hit stays hit....Powder weights are the same as .303 British but you definitely don't have supply hassles with projectiles.

I favour the number 4 action over the others for nothing more than strength and 10 round mags... 2 spare and one fitted are real handy on a big mob of pigs

Dream it, build it...lol.

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Re: Possible .303 conversions

Post by andym79 » 30 Oct 2017, 11:54 am

Just came across this post, glad I inspire thoughts of wildcats!

I stumbled across here because I am now researching a 303 wildcat, probably a 408-303, if its just a single shot so be it!

This has been the year of the wildcat for me have done 4 this year and plan on a bit more oddball stuff next year.
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Re: Possible .303 conversions

Post by andym79 » 30 Oct 2017, 12:55 pm

What needs to be done to the magazine for a 40-303 to work?
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Re: Possible .303 conversions

Post by Tripod » 30 Oct 2017, 6:01 pm

andym79 wrote:What needs to be done to the magazine for a 40-303 to work?

Ok as requested, To do a 444 conversion' Buy a Howa 308 magazine, Cut out the front and bottom of the smle magazine and glue the Howa mag into what is left of the smle mag thereby using the smle mag shell to locate and retain the Howa mag. :thumbsup:
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Re: Possible .303 conversions

Post by bigpete » 30 Oct 2017, 6:23 pm

45/70 necked to 358 with the rim turned down lol I can supply you the cases
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Re: Possible .303 conversions

Post by Tripod » 30 Oct 2017, 6:30 pm

bigpete wrote:45/70 necked to 358 with the rim turned down lol I can supply you the cases

If you have excess 45-70 cases send them my way, I am running low and my local never seems to get them in. :thumbsdown:
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Re: Possible .303 conversions

Post by bigpete » 30 Oct 2017, 6:36 pm

Not really. I do have a bunch of 45/70 cases with the rims turned down to suit a 303 bolt face
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Re: Possible .303 conversions

Post by RoginaJack » 30 Oct 2017, 8:19 pm

Hhmmm, nothing wrong with a straight 303 using 154gr SP on pigs. Hit 'em and they stay hit real quick but that takes all the fun out of a 303 conversion project.
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Re: Possible .303 conversions

Post by AusTac » 31 Oct 2017, 10:00 am

Make it a .50!
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Re: Possible .303 conversions

Post by andym79 » 31 Oct 2017, 1:58 pm

No 475!

A 475 linebaugh would work well. But I think a 460s&w might be good.
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Re: Possible .303 conversions

Post by Tripod » 31 Oct 2017, 5:10 pm

andym79 wrote:No 475!

A 475 linebaugh would work well. But I think a 460s&w might be good.

Both of those are well beyond the pressure limit of a SMLE action, Especially the 460.
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Re: Possible .303 conversions

Post by Tripod » 31 Oct 2017, 6:48 pm

bentaz wrote:
Tripod wrote:
andym79 wrote:No 475!

A 475 linebaugh would work well. But I think a 460s&w might be good.

Both of those are well beyond the pressure limit of a SMLE action, Especially the 460.

Plus I've got an old shot out martini Enfield anyway.

The number of ideas I would like to build on a ME but I never find a donor. :(
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Re: Possible .303 conversions

Post by Mr.Seacucumber » 01 Nov 2017, 9:20 am

Wait how do you make a 30/303? Do you just need to re barrel it? How do you make e cases?
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Re: Possible .303 conversions

Post by Mr.Seacucumber » 01 Nov 2017, 1:48 pm

bentaz wrote:I think you just ream a 303 chamber into a 308 barrel.


Well how hard can that be?

....
.....

I mean how expensive can that be?
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Re: Possible .303 conversions

Post by bladeracer » 01 Nov 2017, 3:36 pm

Mr.Seacucumber wrote:
bentaz wrote:I think you just ream a 303 chamber into a 308 barrel.


Well how hard can that be?

I mean how expensive can that be?


Buy a reamer and do it yourself.
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Re: Possible .303 conversions

Post by Mr.Seacucumber » 01 Nov 2017, 7:33 pm

bladeracer wrote:
Mr.Seacucumber wrote:
bentaz wrote:I think you just ream a 303 chamber into a 308 barrel.


Well how hard can that be?

I mean how expensive can that be?


Buy a reamer and do it yourself.


I'll need reloading dies though?
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Re: Possible .303 conversions

Post by bladeracer » 01 Nov 2017, 7:50 pm

Mr.Seacucumber wrote:I'll need reloading dies though?


Maybe, maybe not. Try the standard .303 dies first. If they don't give enough neck tension you might need a .308 sizing die to size the neck down that touch extra.

You are talking about a simple standard .303 but with a .308 bore aren't you?
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Re: Possible .303 conversions

Post by andym79 » 01 Nov 2017, 7:57 pm

Tripod wrote:
bentaz wrote:
Tripod wrote:
andym79 wrote:No 475!

A 475 linebaugh would work well. But I think a 460s&w might be good.

Both of those are well beyond the pressure limit of a SMLE action, Especially the 460.

Plus I've got an old shot out martini Enfield anyway.

The number of ideas I would like to build on a ME but I never find a donor. :(


Is the ME much stronger?

I am by no means knowledgeable about the SMLE.

Is the No4 any stronger?

I was basing pressure ratings on CIP data, in my opinion the Americans and SAAMI, tend to down rate pressure ratings of most European and Russian rifles/cartridges! I can't think of any reason they might frequently do that ;)

According to American sources the M96 is garbage and is barley fit for the 6.5x55 and could never take a 308, the K98 is okay but so weak compared with their M1903 and the Mosin is just Russian garbage! (on a side note I read about a rifle destruction test where a load with a full case of Unique was used in a 30-06 M1903 and the same in a M91/30, the M1903 failed catastrophically, the author predict even worse failure for the M91/30, it was pretty sick after, but didn't actually fail catastrophically.

Anyway back to the case in point, CIP rate the 303 at 53,000 psi (I assumed that as by the far the most common rifle would be a SMLE, that they based it on that :problem: )
475 Linebaugh at 50,000 psi
460 S&W at 57,000 psi so a define :problem: there!
However the Mosin according to CIP can take 56,000 psi and therefore could theoretically handle the 500 S&W at 54,000 psi.

As I said, I can't speak of the SMLE, but I trust CIP and the Europeans over the SAAMI setup.
Last edited by andym79 on 01 Nov 2017, 8:00 pm, edited 1 time in total.
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Re: Possible .303 conversions

Post by Mr.Seacucumber » 01 Nov 2017, 7:58 pm

bladeracer wrote:
Mr.Seacucumber wrote:I'll need reloading dies though?


Maybe, maybe not. Try the standard .303 dies first. If they don't give enough neck tension you might need a .308 sizing die to size the neck down that touch extra.

You are talking about a simple standard .303 but with a .308 bore aren't you?


Yeah that's the idea, just so I can use 308 bullets, more specifically those Berger ones.
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Re: Possible .303 conversions

Post by Tripod » 01 Nov 2017, 8:08 pm

Mr.Seacucumber wrote:
bladeracer wrote:
Mr.Seacucumber wrote:I'll need reloading dies though?


Maybe, maybe not. Try the standard .303 dies first. If they don't give enough neck tension you might need a .308 sizing die to size the neck down that touch extra.

You are talking about a simple standard .303 but with a .308 bore aren't you?


Yeah that's the idea, just so I can use 308 bullets, more specifically those Berger ones.

The reamer will need to have a .308 pilot instead of the .311 pilot and 303 dies with the expander polished down 3 thou will sort out the dies. Alan Swan did mine on a Siamese Enfield
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