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30/303 Ross rifle

27 May 2022
@ 08:48 pm (GMT)

Sefton Booth

Hey guys long time listener, first time caller.
Green horn on my reloading journey.

A little bit about myself before I get to the gib of it.
I reload for a 30/30 and 2 no5s I have.
All pretty standard loads all in the tables no playing around, all so I can shoot more, more is better right?

Well I recently in the past 6 months bought a MK3 Ross rifle, a genuine commercial sporter chambered in 303. Well the insides looked more like a smoothbore 1700s something.

Long story short, hardy rifle here in Palmerston North rebarreled it for me in 308.
So 303 chamber firing a 30 cal pill.

Has anyone got experience with this combination?
I have some 164 gr hornady eldm? (They're in the shed) and some 180 grain rn Speers.
I'm using 2208 for everything as it's economical across calibers.

I understand the Ross has a strong action as being designed for the 280 Ross, hotter loads? Sorry if I dragged on a bit here lads. Alot of curiosity and nostalgia for days gone by. I got Hardy's to keep the original irons, call me crazy but I believe this gun can be better than I and I'd like to keep it true to the men of the era like Major Wilson etc.

Regards Sefton


28 May 2022
@ 07:45 am (GMT)

Nathan Foster

Re: 30/303 Ross rifle
Hi Sefton, this was an occasional practice in days gone by but the outcomes vary depending on the approach.

If the gun builder uses a .30-303 reamer, then all may be well.

If however the gun builder uses a .303 reamer (the typical she'll be right NZ approach), the case neck and lead will be oversize, allowing the the bullet to move off center during ignition. The rifle may shoot just fine but is handicapped if reamed in this manner.

If the bore has been reamed with a .303 reamer, you will need to use neck dies so as to encourage alignment of the bullet through the loose lead. The neck dies will probably need a tight neck to compensate for case spring back (to the larger diameter) after its been through the die. If using a Lee neck die set, sand the mandrel to a diameter of about .306".

Other matters of accuracy will again depend on your practices. Epoxy bedding, shooting technique, trigger control and observations of evidence will be key factors.

2208 / Varget is a mild pressure powder for the .303 case. You should not get into any trouble with this. Do not expect hotter loads though, as the case to bore ratio has been reduced. Look for sweet spots around the original velocities of 2400fps. If the rifle wants to go higher, so be it, the brass will let you know. But realistically, the focus should be toward accuracy.

It has at various times been common place to find .308 barrels on 7.62x39 caliber rifles, the Mini 14 being a prime example. Russian and Chinese 7.62x39 and 7.62x54R bores may also run to .308" and smaller - but not by design. The intended ammunition consists of a .311" projectile. The net result is the correct chamber, but with a tight bore. Your rifle may have a correct bore, but a loose chamber.

One of the potential issues with using a custom .30-303 reamer, is that if the rifle is sold on, somebody may try to jam factory .303 ammo into the chamber. This differs to the Russian / Chinese examples due to the fact that those rifles have generous chambers to offload pressure. If one were able to fit a .303 load into a .30-303 chamber (slim possibility due to extremely tight fit), the results could be disastrous.

28 May 2022
@ 08:16 pm (GMT)

Sefton Booth

Re: 30/303 Ross rifle
Hey Nathan

Thanks for the reply mate.
You explained that really well.
I have got the mandrel to .307 on my Lee collet die, seats the projectile in my humble and limited opinion quite well with good neck tension. I'm in a habit of crimping everything I load, comes with Lee sets so have got into the habit of doing it.

I'll have to ring the Smith and find out and /or put some ammunition through it and see what size the neck comes out at?
Really would pay dividends if I had educated myself on the possible pitfalls of the conversion before shelling out dollars. That's life though live and learn.

I will look at expoxy bedding the rifle at some point with your products as I had great success with your product on a synthetic stocked jungle carbine.
Without tooting your horn too much, great products (I had to form the draw area in this case as it was a total void) the stock stabiliser compound tools well. That bedding compound, Jesus rock solid alright and great book series mate.

Thanks for confirming alot of things and pointing out potential pitfalls in regards to the way it could be machined.
This Ross won't be for sale anytime soon.
Who wouldn't like shooting a 110 year old straight pull 303?
Well I am a biased 303 man.
Anyway I babble on.

Thanks Nathan

29 May 2022
@ 08:19 am (GMT)

Nathan Foster

Re: 30/303 Ross rifle
Hi Sefton, thanks for your kind words.

Measuring the diameter of the neck to determine the chamber design might be a little tricky in this instance. The problem is that the .303 has a thin case neck. The .308 is heavier.


.303 chamber min spec:

Case mouth .341"
Case neck / shoulder junction .345"

.303 ammo max spec:

Case mouth .338"
Case neck / shoulder junction .3400"

.308 chamber min spec:

Case mouth .344"
Case neck / shoulder junction .346"

.308 ammo max spec:

Case mouth .3435"
Case neck / shoulder junction .3435"

It would seem that the .308 has a larger diameter neck. But again, the numbers are based around differences in case thickness. The above does not take in the throat design.

A little bit more...

Typical loaded case neck:

.303 ball neck .337" .303 Highland neck (NNY / PPU) .3355"

.308 Win Powerpoint .332"

Typical fired case in max chamber spec rifles:

.303 .345"
.308 .346"

The above last two numbers are the ones you will be most interested in. As you can see, it may be difficult to determine the reamer design via fired cases. It will therefore be easier to ask the smith about the reamer that was used. (Edit: Having said this, if .303 brass comes out of the chamber at around .344 to .345, we can assume it was a .303 reamer, not a custom 30-303).

Otherwise, there comes a point when we have to part ways with theory and look to the evidence. Bed the rifle, work up loads, focus on technique and let the rifle do the talking. It may be good or bad or perhaps something quite acceptable in between. If you were to do it over, it would be better to go with a custom reamer, but this would require quite a bit of planning, considering the difference in the cases. Some love this sort of thing (the details), others don't. One could also just as easily use the above to pull up faults in the typical .308 rifle. The trouble is, we can take information, combine it with imagination and develop a bias which may interfere with our processes and results. If you go into this this thinking - it will never shoot well because its it has a loose chamber, such thinking might inhibit your processes. Take this info into account, but don't allow it to cause you to pass a premature negative judgement on the rifle.



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