Home Forums Hunting & Shooting Ask The Gunwriters 257 roberts +P

I got a 257 bob at the beg. of hunting season Its a custom of some kind with a mauser action beutiful gun and it shoots great I am going to load some loads and i cant figure out the +p is it like ackly or what. I have a 2506 243 708 and have been reloading for about 25yrs . Can anybody help me with this thanks marty

The +p usually stands for + pressure - aka, higher pressure loads. As always, if in doubt on the chambering, have a chamber cast done. You say that you have apparently fired it, do the cases look like standard .257 Roberts cases or "improved"? Also, is the +p on the ammunition you're using or on the rifle itself?
Selmer

Thanks for the imfo. The cases fireform the same so im sure its standard I have just seen this in books and in art. with no exsplaniaton Sorry about my spelling I was making sure im asume it has to do with the newer powders that they didnt have back in the day thanks marty

The 257 Roberts was developed from the 7x57mm Mauser which was originally chambered in the Mauser M93 rifle. This rifle was not as strong as later Mausers, so the 7x57mm was loaded at lower pressures than later cartridges. Any later Mauser (M96, M98) or other strong actions can easily handle higher pressure loads. What model is your Mauser?

The +P is a designation of ammunition loaded to higher pressure than the "standard" loading. For some reason, the .257 is loaded to a lower pressure much like the 6.5x55, although i am unsure why. Anyway, the +P loads are considered safe in modern rifles chambered for the .257. If your rifle is marked for +P, you have no problem, otherwise, you might want to check witha a gunsmith before using the higher pressure ammo.

NOT sure what mauser action it is its in very nice shape no markings other than #p84783 on 1 side and 72 on the other thanks marty

Basically it was a new pressure 'spec' for the cartridge. So a +P designation gives the 'official' sanction for using the higher pressure rounds as per the SAAMI specifications. In theory rifles and brass should be 'stronger' to meet the 'new' +P standard. In practice it's probably only older rifles (e.g. converted from old military Mausers) that might be questionable as far as meeting the higher +P 'standard'. Personally I'd like to see more 'new' +P standards for older cartridges, such as the 7x57.

There are TWO commercial loading levels of the 257 Rbts in the US according to SAMMI

The standard loading is set at 45,000 CUP
The +P loading is set at 50,000 CUP

For reference the 7x57mm is set at 46,000 CUP
The 30-06 is set at 50,000 CUP

About your custom Mauser action ... Does the firing pin cocks its self when the bolt is opened, or when it is closed ?

If you can answer that question I can help you in finding out what model of Mauser design you have.

It cocks when its opened thanks marty I would appr any imfo you have it also has a tang safety

If it cocks the firing pin when it opens then it is based on the M98 design. All other earlier Mauser designs (93,95,96)cock the firing pin when you close the bolt.

The M98 is safe to use with the SAMMI +P rating for 257Rbts if it is in good condition. (No abuse to the action) That means you can run at the same level of pressure as the 30-06 and such.

You should be fine with ANY factory loaded 257 Roberts loads.

Or, it could mean that a Model 93 was converted to "cock-on-opening". There were several drop-in modifications (with some gunsmithing) available that might have been installed. Best is to have a knowledgeable person look at it.

tang safety? on a Mauser?

If it is a Model 98 it will have a small third safety lug towards the rear of the bolt that fits into a corresponding recess in the receiver.
Mike

My '06 has a tang safety. Pure commercial 98. Austrian Voere barrelled action.

Thanks it has the third lug Thank youall for all the help thanks again marty

Marlow,
If it has the 3rd lug and you are sure you know what you are looking at you should be good to go plus p.
It sounds like you have an interesting rifle there, would love to see a picture.
It souds like a commercial action to me but I supose there might be military mausers with tang safties, but I do not recall having seen one.
Any way its a great carrtidhe and very popular here on the 24 Hr gun talk !
...tj3006

I will to post a picture with my daughters help as you can see im not very internet smart thanks again marty