I would like an explanation about action-cartridage fit.

Discussion in 'The Basics, Starting Out' started by Yorkplates, Mar 12, 2006.

  1. Yorkplates

    Yorkplates Well-Known Member

    Jan 10, 2005
    I would say that over the past several months that I have learned quite a bit about action lengths, circumference, bolt face sizes, etc. and their relationships with certain cartridges. There is a little gray area that I would like to address. It is concerning the 257 Roberts. Why is it considered a bad idea to try and build this rifle on a short action? I understand that the 7X57 case, that it is derived from, is .2" longer that the .308 case, but the bullets that come factory loaded and even handloaded all keep The OAL shorter that my 168gr .308 Matchkings. The largest grain size I have seen is 120gr Nosler partitions. I'm looking at one now and it is shorter than the .308 mentioned before.

    My dream light-carry rifle would be my Kimber Montana in 257 Roberts with 110gr Accubonds. The rifle is chambered in 308 and I thought with an identically contoured barrel in 257 Roberts from one of the custom barrel guys, it would be a classy little whitetail slayer. It would even add a little more meat to the barrel, having a smaller bore. I just don't understand why it is a bad idea. The 120s fit very well in the blind magazine and seem to feed fine. I really would appreciate it if someone could clear this up for me.

  2. Michael Eichele

    Michael Eichele Well-Known Member

    Jan 6, 2003
    I am not sure where you have heard its a bad idea but I think thats one major selling points of compact cases is a short action.

    I think some shooters like to seat those bullets as far forward as possible and that extra .2" wont permit those shooters to load em the way they like. If you can live with a bullet seated way in the case then its a great idea. This is of course there is something I am not aware of about this case here.

  3. Yorkplates

    Yorkplates Well-Known Member

    Jan 10, 2005
    I understand about the other compact cases being desired because of the short action. I have just read in a few places that the 257 Roberts isn't a good idea in a short action.
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Jun 12, 2004

    The 257 is really in a shady middle ground as far as being called a short action round. In reality is is not a true SHORT action design. The reason is because of its case length.

    If you look at the true short action rounds, the first thing you think of is the 308 Winchester based cartridges, 243 win, 260 Rem, 7-08 Rem, 308 Win, 338 Fed, 358 Win and such. These cases are roughly 2.045" in length, perfect match for a true short action receiver.

    Next step up in case length you get into the 284 based wildcats and parent case. These have a case length of 2.170" in length or slightly more then 1/10" longer then the 308 based cases. This length is getting tight in receivers such as the Rem 700 except in the smaller calibers with the lighter bullets. The heavier bullets can be used in the 284 based rounds but in a repeating role in a Rem 700 SA, you have to specifically design the throat very short to allow reaching the lands with handloads and still being able to feed through the magazine.

    The 284 based rounds are about as long as you can practically fit into a Rem 700 SA as a repeater and these are a tight fit at times.

    Now if you compare those to the 257 and also the 6mm Rem and 7x57 you will see they have a case length of roughly 2.233". Again, noticablly longer then even the 284 case. Basically these split the difference in case lenght from the 308 based cases to the '06 length cases.

    The 6mm Rem can have its bullets seated very short and still work well in a short action receiver. The 257 and 7mmx57 can as well but the bullets need to be seated very deep to work. It is really a cramp to do this in a true short action receiver.

    It is for this reason that you generally hear them being chambered in standard action length so that you can seat the bullets out where they really should be and not taking up so much case capacity like they have to in a Short Action.

    Hope this clears the mud for you some!!??? /ubbthreads/images/graemlins/grin.gif

    Kirby Allen(50)
  5. Guest

    Guest Guest

    I have been using a .257 Roberts for a long time it is a Browning Safari long action.I had it throated for 117 gr Sierra's for a deer/antelope load.The reason was to utilize the full potential of this ctg.In the past the factory loades were weak and the reason was as a then it was a wild cat and many guns were built on old weak 93 or 95 Mauser actions.In a modern actions this .257 can be loaded to produce near 25 06 balistics. My own load pushes a .117 bullet at 2960fps and has taken deer at 400yds +. This was when I thought that was long range.
    Old Bear
  6. ATH

    ATH Well-Known Member

    Oct 7, 2003
    The 300 WSM falls into this gray area too, does it not?
  7. davewilson

    davewilson Well-Known Member

    Feb 19, 2004
    OCC, this case with the 7mm bullets has a longer COL than when it's a 25 cal. if your loaded round is short enough for good magazine function with the 110's, i'd say it's perfect for a short action.just make sure the throat is compatable with the rounds that are going in the magazine.