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Overall length question

Discussion in 'Ammunition & Reloading' started by evltwn, Jul 19, 2011.

  1. evltwn

    evltwn Gold Hill Oregon Bronze Supporter Bronze Supporter

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    Folks, I am hoping for clarification regarding establishing OAL for my Savage model 12 .22-250.

    Using a Hornady comparator, I have determined the length of the cartridge to the ogive of a Hornaday 55 grain V-max. I then subtracted .025 from that length to establish "jump". A loaded round chambers easily.

    The question I have, is that after doing that, the OAL of my round, when measured from the base of the case to the tip of the projectile is quite a bit longer than the OAL listed in my reloading books. Also, I have measured OAL on some factory rounds, and they are quite a bit shorter than the one I have reloaded.

    Are factory rounds that much shorter than a round loaded for a specific chamber dimension? :confused:

    I await the collective wisdom of the reloading gurus to point me in the right direction, or perhaps tell me where to go...
     
  2. Mark W.

    Mark W. Silverton, OR Bronze Supporter Bronze Supporter

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    If the rounds will feed and function from your magazine and there is still plenty of bullet in the neck you should be fine.
     
  3. motoman98

    motoman98 Gresham, OR Active Member

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    The loads' OA as specified in the manuals, allow for feeding in all magazines. If longer functions well in yours, great. Especially in short actions, the mag is usually the limiting factor.
     
  4. 2506

    2506 Seattle Well-Known Member

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    The short answer is yes. Getting the COL optimized to the rifle is great for improving accuracy. Don't let risk-averse loading manuals or factory rounds fool you. Heck, some benchresters let the rifle's action seat their bullets. And motoman is right, the mag usually puts a limit on how far out you can go.
     
  5. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    OAL's shown in reloading manuals are usually just a Minimum OAL. This is specified for a specific bullet to make sure that there is still enough volume remaining in the case for the powder charge to keep pressures from going too high. Loading longer than the OAL shown is rarely an issue unless the bullet is being jammed into the lands and a pressure spike is caused.

    Factory ammo is loaded to fit as many firearms as is possible in the specific caliber. Accuracy is not as big an issue as loading from a magazine and fitting the chamber.

    As others have stated loading longer often increases the accuracy although every rifle has it's ideal "jump". When fine tuning your ammo for accuracy first find the load that he rifle likes best. Once that has been determined, then play with the OAL until you are shooting the smallest groups possible. Also as others have stated, the magazine will limit the OAL if you intend on shooting multiple shots without reloading. If only shooting single shots, the longest that will shoot accurately is perfectly OK.
     
  6. evltwn

    evltwn Gold Hill Oregon Bronze Supporter Bronze Supporter

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    Thanks, everyone, especially Deadshot! Gotta reload...gotta shoot...gotta reload...
     
  7. noylj

    noylj high desert Active Member

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    The COL is determined by your chamber, the lede, and the bullet ogive. You have established a COL that is a bit longer than I normally find optimal, but it gives you a place to start. The only question is does it fit in your magazine? If so, you are good to go. Just keep track of all you loading variables and what accuracy you get.
    COL of factory ammunition must fit the tightest SAAMI chamber and just a bit less. The COL in loading manuals is a "DO NOT REDUCE" number and is often the SAAMI required maximum COL for TESTING, and has nothing to do with your reloads and everything to do with keeping the companies on the same page when testing.
     
  8. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    I would be very cautious in dismissing the "Do not Reduce" admonition. It is often placed there AFTER testing by powder manufacturers. A case in point is the OAL specified by Vihtavouri Powders for using 3N37 in 9mm loads. Their published OAL is there to keep the cases from blowing up/out due to the pressure curve of this powder. Reducing below the 1.142" dimension runs the pressures too high for safety. It may not blow the bottom out of every case but it only takes one.

    Then if you are someone that loads their ammo to the minimum to get the job done, and never come close to maximum load/pressure for a given caliber, you will have more room to "ignore" this dimension.