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Thread: 243 small rifle primer cases

  1. #1

    243 small rifle primer cases

    A little while ago I remember seeing that Lapua had started producing 308 cases with small rifle primer pockets for the US palma rifle team, the recorded benefits where that extreme velocity spreads were reduced, the implication being that this would increase consistency and therefore accuracy.
    So I got to thinking that I could resize some of these and potentially enjoy the benefits of a small rifle primer pocket in 243winchester.
    Now as clever as I think I might be!!!!!! I cant believe that somebody else has not already tried this, am I barking up the wrong tree, or is this not as straight forward as it appears?

  2. #2
    Having had no replies, the basic thought process was going something like this.

    Most of the really accurate bench rest calibers seem to use small rifle primer pockets 6mmbr etc and a lot of the more recent commercially developed accuracy rounds by lapua appear to also use this primer format, 6x47 6.5X47 etc. Now as 6 X 47 is basically a slightly shorter .243 case with a small rifle primer pocket (I think), perhaps I could derive the benefits of the small rifle primer pocketed case, able to withstand slightly higher pressures, more consistent ignition of the powder column (or so it seems), in my standard .243.
    The only problem I can see is that the primer might not be man enough to ignite some of the slower burning powders vit n160 h4350 etc that you might try to push the heavier .243 bullets (85gr-100gr etc) along with.

    Could this give some of the accuracy benefits you would expect from a custom rifle from say a standard Howa 1500 without the cost.

    If any of you have any thoughts on this, I really would appreciate your replies

  3. #3

    I will pitch in my thoughts.

    Firstly, there will be a lot of case prep work required when necking down a .308 case to a 6mm bullet size in getting rid of the excess brass. Is it worth this time consuming process? Why not go for something like a 6x47 which already is only half a millimeter away from your desired case in standard form and will no doubt produce almost identical results? 6.5x47 Lapua cases available off the shelf.

    I also personally feel that the benefits to be gained if any, would not be seen in practical deer stalking applications. Shooting at targets at longer distance disciplines perhaps might show a benefit.

    I don't want to take the wind out your sails, but when you look at what some of our American friends (and our own countrymen) are doing with regards to case or cartridge innovative development, I would be surprised if this sort of thing has not been looked at and for whatever reasons discarded. Perhaps someone on here will eventually read your post and know a lot more about it than me.

    Good luck with your venture regardless.

  4. #4
    if you are asking would you get custom rifle grouping of say the .2"-.3" from a standard Howa buy using .243 ammo with small rifle primer ,i really doubt you would get that grouping . what you would benifit from is consistant brass prep trial diffrent powders and try diffrent neck tensions on cases you shoul;d see groups getting smaller this way

  5. #5
    Hi, jamross65, griffshrek,
    I thought about 6.5x47 and 6X47 cases but considered that it might be asking a lot for the cases to grow by 4mm pluss to get to 243 length, I already do all the case prep etc and get some cracking groups from 75 grain or less heads, however I have been trying to get 100 grain heads to stabilise in my Howa varmint but stated getting pressure signs on the primers when I started pushing the velocity up, it realy needs a new barrel with a higher rate of twist probably 1:8 rather than the 1:10, but if I am going to go to that expense then I wiil probably just build a new rifle in 7mm08 and keep the 243 for foxes etc.
    If it does work it would be great, but it is such a simple idea someone has got ot have tried it already.
    Last edited by DCG; 15-02-2011 at 16:30.

  6. #6
    Lapua 6x47 brass is designed for high pressure with a thicker web than a 243 has.

    If your intention is to be able to push your pressure up, in order to get your velocity up, in order to stabalise a 100 grain bullet in your twist; might I gently suggest that you are following a path to perdition. I would very much doubt whether you could safely ramp up the load enough to stabalise the bullet.

    The small primer brass is a application of an old idea that found fame in the 6mm PPC and was found to give more uniform velocities than a large primer by some authorities. It appeared that the smaller flashole was of more significance than the primer size per se, but that in high pressure designs a smaller primer pocket left more meat in the case head. This effect was detectable ( or not according to the study ) only in finely tuned, ususally tight necked competition guns. The improvement in factory sporter rifles is very likely to masked by any number of other factors.

    This is quite apart form other sdesign factors like the shape of the powder column and shoulder design which are apparently perfected in cases like the PPC and x47.

    You may or may not need to neck turn as well.

    If you are looking at moving to small primer for an accuracy point of view, fire a series of 5 or better 10 10 round targets with your best large pocket load, do a batch of small primer cases and do the same again. Nobody can tell you excatly what the effect in your rifle will be but if you do decide to find out make sure you shoot enough groups to have some meaningful statistics on whether it has helped or not at the end of all that expense.

  7. #7
    Just been on midway uk website, lapua 308 palma cases about 20 cheaper per 100 than lapua 243 cases

  8. #8

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