.257 Roberts OAL Question

280SOLIDBASE · May 14, 2014

Getting ready to load some test loads for my son's .257 Roberts. I checked the rifle's (Remington Model Seven) chamber for overall length using the Hornady OAL length gauge & Hornady bullet comparator.

What I came up with measured to the ogive of the bullet (100 gr. Nosler Partition) was 2.479", which translated into FULL overall length is 2.980" which does NOT include an estimated .010-.020 deeper for bullet "jump". I do know that at that length, there is not a lot of bullet in the case neck. I can't say exactly what it was, but I remember holding a bullet beside the loaded dummy round, there wasn't much in the neck.

The Nosler #7 Manual shows a maximum OAL of 2.780". I can't even measure to the ogive on a factory round of Nosler Trophy Grade 110 gr. AccuBond as the bullet comparator part of the measuring system goes the whole way to the mouth of the casing. The full OAL of the Nosler factory round measures 2.752".

My question then would be, IF the reloaded round would function in the magazine at the full OAL of 2.965" (added in .015" for jump), would it be advisable to go ahead with that length? I am wondering because the factory round is sooooo much shorter.

I have not had the time to actually attempt to see if that full OAL length would function in the magazine.

Thanks in advance for any input.

SJB358 · May 14, 2014

I would load as long as the magazine permits then work back from there. If the magazine only allow's roughly 2.8" then load for decent function and work from there.

DrMike · May 14, 2014

Measure your magazine. That may well be the determining factor for your work. My 257 Bob (Remington CDL) measures with a 115 grain PT at 2.460 to the ogive. Therefore, your measurement is likely pretty close to my own. Were I to use a 100 grain bullet, it would likely give a measurement akin to what you register. A 100 grain Hornady SO measures 2.457 inches to the ogive. There is ample bullet in the neck to ensure good tension.

JD338 · May 14, 2014

The M7 is a short action and the magazine max length is approx. 2.800" so the COL of 2.980"
will not fit in your action. It will function in a standard length action. My 700 Classic 257 Roberts is a long action and I load it to 2.900".

JD338

truck driver · May 14, 2014

I think I read some where that the seating depth needed to be at least the same as the bullet diameter for enough neck tension.

280SOLIDBASE · May 16, 2014

Thanks guys. I am going to jump on the .257 Bob project after I wrap up my .264 project, which will hopefully be in 2-3 weeks. I still need to replace the stock on the Model Seven as it is just too nice a chunk of wood for a 12 year old to be clanking around in the woods with. Not much sense in working on a test load until I have the permanent stock on it. I think I may pick it up this coming week.

ScreaminEagle · May 16, 2014

truck driver":wtiy70ts said:
I think I read some where that the seating depth needed to be at least the same as the bullet diameter for enough neck tension.

THIS!

Oldtrader3 · May 16, 2014

My long Browning HP action .257 Roberts measures COAL at 2.930 but mine has been freebored and has full length Browning magazine.

steve4102 · May 17, 2014

truck driver":2r5p01k7 said:
I think I read some where that the seating depth needed to be at least the same as the bullet diameter for enough neck tension.

One place you will find it is in the Nosler Manuals.

Read the last paragraph. There is more to this then just finding Max OAL.

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