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Old March 21, 2013, 04:59 PM   #1
mattL46
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Smith corona 03 A3 caliber trouble

Just bought a sporterized old smith corona made 03 I'm a bit perplexed because a stamp on the barell say 308 MAG. That is all
..I've never heard the 308 Winchester called this. Is it a nickname or is there indeed a magnum 308 win. Brethren. Please help I'm worried I screwed up.
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Old March 21, 2013, 05:20 PM   #2
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it could be a 308 Norma magnum. best bet is to check with a gunsmith.
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Old March 21, 2013, 05:22 PM   #3
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I considered that (Norma mag) but just find it odd. I won't feed it until I know for sure. For sure is a chamber cast.
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Old March 21, 2013, 05:28 PM   #4
tahunua001
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the only 308 magnum I can think of is norma, everyone else seems to prefer 300 mag designations...

you definitely need to have the chamber cast, for all you know it's some wild cat that necks a 50 BMG down to 30 cal...
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Old March 21, 2013, 06:50 PM   #5
Jim Watson
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A chamber cast is the safe way to go.
BUT the .308 Norma was specifically designed to rechamber .30-06 without too thin chamber walls in a 1903 or A3.
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Old March 21, 2013, 07:05 PM   #6
mattL46
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thanks guys illl look into it
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Old March 21, 2013, 09:33 PM   #7
jrothWA
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May want to...

consider rebarreling with a 03A3 barrel and get a bolt body, if yu want to restore to 30-06.
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Old March 21, 2013, 11:33 PM   #8
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Ya know Ive been researching the crap out of the Norma cartridge and I have this feeling that my 03 is going to end up being chambered for it. And as big of a pain as its going to be...I'm kinda look ring forward to getting to know it. Part of me hopes that's what it is.
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Old March 22, 2013, 05:43 AM   #9
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no pain,just get dies for it and use 338 win mag cases, they neck down with no problems and maybe a little trim and you are good to go. its a fine cartrige. eastbank.
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Old March 22, 2013, 07:12 AM   #10
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If you have access to a Sierra loading manual,they have both .308 Norma and 30-338 pages,along with cartridge drawings.

Norma created the .308 Norma product with(my understanding) no rifles commercially chambered for it initially.

They had a program where they rented reamers to gunsmiths who were doing their bread and butter job at the time,converting mil-surps.Normacreated an ammo market.

It is slightly shorter than the .300 Win mag.IMO,it is a little better as far as having room in the magazine to seat the bullets out a little further.

After forming the cases,check length.They could be a touch short,as I recall.I suggest just a minimal cut with a case trimmer to square and uniform them.

Excellent cartridge.

While it may be possible to retrofit it back to 30-06,and Criterion makes a good replacement 1903A3 bbl,

A bolt and extractor will be necessary,but what may bite you,sometimes a little work was done on the feed rails for the fatter belted cartridge.

If so,you may find the 30-06 rounds spew out the top of the action.
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Old March 22, 2013, 11:30 AM   #11
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Well again I'm kinda looking forward to it. But it does kinda suck knowing it would take a new bolt considering the original has been shortened due to the longer length. Did I understand that correctly?
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Old March 22, 2013, 03:09 PM   #12
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The bolts were not "shortened due to the longer length" of the cartridge; the bolt face and extractor were altered to accept the larger head/rim size. Yes, a new bolt will be needed.

Jim
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Old March 23, 2013, 06:39 PM   #13
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The Norma 308 mag is based on the 30-338 wildcat. I think other than shoulder angle its the same. I know from personal experience the 30-338 is an awsum cartridge.
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Old March 23, 2013, 10:07 PM   #14
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The bolt face would have been enlarged for the .532 belted magnum case head. Bolts are fairly common for the 03 & 03A3. The 308 Norma mag is not hard to form or load for but considering the age and wear on the action, I'd stick with moderate loads.
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Old March 24, 2013, 10:03 AM   #15
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Pardon my confusion James K.
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Old March 24, 2013, 10:05 AM   #16
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Hawg and mobuck. I look forward to getting some 300 win mag cases for forming. I'll be keeping it in the Norma cartridge. I'm no velocity chaser so light target loads are right up my alley. I'm happy to have something a little different.
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Old March 24, 2013, 11:28 AM   #17
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When they say light loads, what is meant is that it is best to stick to loads at the beginning end of the listings, not ultra light powder puff loads.

You want to use a powder that fills most of the case. Due to the large case volume, a very light powder charge can sometimes do wierd things, including detonation!

IT isn't common, and as far as I know, hasn't been able to be duplicated with regularity in testing labs, but it has happened many times over the last half century, with big magnum cases and light charges of powder, especially a light charge of a slow burning powder.

Stick to loads on the light end of what the .308 Norma is capable of and you should have no trouble from the ammo.

The rifle, on the other hand, depends entirely on who did the work, and how well. Have it fully checked out by a competent gunsmith before use.

Having just the chamber & headspace checked isn't good enough. Besides the question of how well the work was originally done, there is also the question of what ELSE a previous owner did to, or with it. They made it a magnum, did they perhaps shoot balls to the wall loads out of it? Enough to overstress things? erode the throat? etc...

Have it fully gone through, by someone who knows what to look for (and how to look) before considering it fully safe. Bubba is not the right guy to tell you this.

Good Luck
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Old March 24, 2013, 12:50 PM   #18
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Good info 44 amp. I know not to load too light. I'll definitely have it checked. I'm a little embarrassed by my "shortened bolt" statement earlier. That was a no brainer a little thinking was all was needed. Considering you can't shorten on of those ha ha. I come from a lineage of talented gunsmiths so confidence in a good look over won't be hard to get done. I'm very cautious about any new fire arm. Especially one that was modified and not by me. Thank you all for sound information.
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Old March 24, 2013, 01:02 PM   #19
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It not a no-brainer, as custom gunsmiths have been known to shorten both bolts and actions to make a special, short action rifle (called "Kutrz" actions) - especially in the days before what we know today as short actions were abundant & widely available.

The .308 NM's a louden-boomer, & not something I'd want to plink with very much with, even with mid-range loads - but makes a pretty decent long range/plains game rifle.



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Old March 24, 2013, 02:26 PM   #20
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Thanks petah. Yeah I'll shoot it awhile and either convert it or sell it. If I'm not happy with it anyway. Im ready for a shoulder bruiser.
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Old March 24, 2013, 03:30 PM   #21
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Is the 1903A3 action capable of taking a .308 Norma Magnum?

The case is 2.56" long, the .30-06 is 2.494. That seems to me it would be enough to cause real problems.
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Old March 24, 2013, 03:42 PM   #22
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Tha action can take the cartridge length but once the feed rails have been altered to feed those cartridges you can't go back to 30-06.
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Old March 25, 2013, 10:59 AM   #23
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It will be easier to neck 7mm Rem mag up or 338 Win mag down than to form 300 Win mag. The shoulder is further forward on the 300 forcing you to move that shoulder back. If you do this, you'll need to neck ream the finished 308 Norma case or you may have problems later. I used 338 cases since I don't like to form anything from a cartridge that I already use(7mmRem mag&300 Win mag). This precludes the faint possibility of misidentification of ammo by someone other than myself. In addition, necking 338 down allows you to precisely control the base to shoulder length preventing or reducing the possibility of case stretching during fireforming.
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Old March 25, 2013, 11:25 AM   #24
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there is a set of 308 norma dies for 55.00 on gunsamerica. eastbank.
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Old March 28, 2013, 09:02 PM   #25
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That makes sense mobuck. I did buy a hand full of 300 mag brass from a friend...I'll look into getting some 338 and tinkering with it. Any other steps required to neck down? Mind explaining how you do it? And how much needs to be removed from the 300 mag considering I'm already out of pocket on them and should try to use them. @ east bank thanks for the heads up!!
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