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Thread: excess headspace?

  1. #1
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    Default excess headspace?

    Scratching my head a little on this one but have some ideas and just want additional input in case I may have overlooked something. I have two .300 win mags, one is a 98 mauser and the other is an Eddystone Enfield. I am trying to work up some loads for these and have run into a situation where the 98 will function properly but when I shoot the same round through the enfield I have issues with the case clinging in the chamber (have to really pull hard on the bolt to eject). Any ideas? The load is 74 gr of IMR 4350 with a 180 swift scirrocco. Barrel lengths are the same and the same gunsmith built both guns but the enfield has seen more trigger time. I here how the .300 can errode the throat but not sure if this would cause the clinging or not. Any ideas would be appreciated.

  2. #2

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    I would say that the Enfield has a tighter barrel, or less free bore to the lands, either of which can cause higher pressures; or possibly just a rougher finish on the inside of the chamber, which in combination with a hot load can cause difficult extraction. There are a couple more questions that might help get your answer--are the shells tight to close the bolt on before they are fired, and how do the fired primers look--are they very flat with sharp corners, and are they flatter in the Enfield? Anyway, sticky extraction is almost always due to excessive pressure, in my experience.
    Regards,
    Jim

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    what is the condition of the brass you're using? Once fired? New? Many firings?

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    Brass is new unfired first load. Primer hits look like they should in my opinion. No excess denting or ringing. I was hoping that they would both be able to handle this load but may just have to settle on a little less fps and find something that will work in both.

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    Possible one rifle had a chamber cut with a worn reamer is on the tight side, maybe, maybe not.

    Anyhow, dies should be matched to the rifle and cases sized till the bolt will just close easily. Every chamber is different. Good idea to have a set of dies for each rifle and adjust them once and be done with it.
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    A tight bolt after firing, is a pressure sign.

    It should be accompanied by other pressure signs, like some rubbing on the case head, and maybe very flattened primers. Primers don't always tell you, when the pressure is too high.

    Your load may be hot, even too hot, for both rifles, but only showing pressure signs for one of them.

    As has been said, no two chambers, barrels, (RIFLES), are the same, and they're not gonna handle pressure the same.

    I would back off on the powder charge. I wouldn't worry about a few fps. A 30-06 is plenty gun, and your 300 Mags. are gonna beat that, easily

    It's good to have the same ammo for both guns. But the requirements for seating depth, and sizing would be different. You could FL resize, and the cases should fit both, and seat the bullets to a length that is suitable for both rifles.

    I'm gonna do that for a cupla 7x57s I have.

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    One possibility is the Enfield as a rough spot or a small groove in the chamber. This is usually caused by a chip getting caught on the reamer and gouging a small area. this hangs on to the brass during firing and changes the reaction of the the brass. Sometimes it ain't easy to see. I would get a chamber cast of both rifles and compare the two if possible. I had a Kimber from the factory that had a ring guage in the chamber, at first the company said shoots fine with factory loads. I sent it back again to get fixed, and it was. That rifle will now shoot 1/4 " groups, if I do my part and I can re-use the brass.

    Chris

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    Another possibility, a little remote but possible, is the gunsmith made one chamber just a little longer than the other. A chamber cast of both can tell you a lot of things if compared side by side.

    Chris

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