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Thread: Start loads and Factory ammo

  1. #1

    Start loads and Factory ammo

    Yesterday evening I sat and de-capped a couple of hundred once fired .243 cases I had been given.
    91 Federal and 102 Nosler, they have been cleaned so I looked the outside over for damage and then just popped the primers out.
    A few cases would not fit in the shell holder so I put them to one side, once all that fitted were done I looked the odd ones over more closely.
    15 were federal and 3 Nosler, all had one thing in common, badly cratered primers, enough that they didn't slide easily in to the shell holder.
    I re-seated the primers with a lee hand primer tool and tried again, all bar 3 of the federals de-primed easily, the 3 that didn't fit the shell holder
    all had damage in the extractor groove, so I binned them.

    Later on while consuming a bottle of red wine I got to thinking, as responsible re-loaders we start at a lower powder charge and work up...
    What do factories do, their ammo has to be safe in any well maintained rifle ?
    So is some factory ammo too hot for some guns, hence the cratered primers, or is it more likely the rifle that fired them had a fault ?
    I had also noticed that the minimum book OAL for 75 grain v-max ammo is 2.640" but factory ammo I checked is 2.560' ?
    Something else that would give a higher pressure for a given powder charge.

    Neil.

  2. #2
    Quote Originally Posted by Hornet 6 View Post
    Yesterday evening I sat and de-capped a couple of hundred once fired .243 cases I had been given.
    91 Federal and 102 Nosler, they have been cleaned so I looked the outside over for damage and then just popped the primers out.
    A few cases would not fit in the shell holder so I put them to one side, once all that fitted were done I looked the odd ones over more closely.
    15 were federal and 3 Nosler, all had one thing in common, badly cratered primers, enough that they didn't slide easily in to the shell holder.
    I re-seated the primers with a lee hand primer tool and tried again, all bar 3 of the federals de-primed easily, the 3 that didn't fit the shell holder
    all had damage in the extractor groove, so I binned them.

    Later on while consuming a bottle of red wine I got to thinking, as responsible re-loaders we start at a lower powder charge and work up...
    What do factories do, their ammo has to be safe in any well maintained rifle ?
    So is some factory ammo too hot for some guns, hence the cratered primers, or is it more likely the rifle that fired them had a fault ?
    I had also noticed that the minimum book OAL for 75 grain v-max ammo is 2.640" but factory ammo I checked is 2.560' ?
    Something else that would give a higher pressure for a given powder charge.

    Neil.
    Happy New Year Neil.
    Factory hunting ammo is loaded to SAAMI maximum allowable pressure in most cases. This for two reasons: First, performance. It doesn't do to advertize that you have a kinda fast load the hits with sufficient energy. You what to be able to say that it is faster and hits harder than anything else out there. Second is economy. Manufacturer's powders are engineered to give ease of handling, maximum performance with a minimal quantity. Often quicker than we might use so that it hits peak pressure/velocity with less powder. (this is not always true but it is in many cases)

    This is why the relative expansion test*is acceptable for handloaders, with some loads. It is presumed that factory ammo is loaded to SAAMI max.~Muir

    (*Fire ten factory loads in your gun and the the average of measurements taken over the head area of the cartridge. Your handloads should not exceed that expansion when using new brass of that same manufacture)
    Last edited by Muir; 01-01-2013 at 12:32.

  3. #3
    Thanks Muir, I wondered how it was done.
    Not sure I want to actually buy factory ammo though, just think how many rounds I could load for the same money

    So the damaged primers I found are likely to be caused by a fault with the rifle in question, over size firing pin hole, over strong firing pin spring etc ?

    Neil.

  4. #4
    Quote Originally Posted by Hornet 6 View Post
    Thanks Muir, I wondered how it was done.
    Not sure I want to actually buy factory ammo though, just think how many rounds I could load for the same money

    So the damaged primers I found are likely to be caused by a fault with the rifle in question, over size firing pin hole, over strong firing pin spring etc ?

    Neil.
    Not exactly. If all were fired in the same rifle it would boil down to a combination of the rifle, the particular primers, and again, maximum pressures. Remember that cratered primers are a sign of max pressure in rifles in good working order as well.

    I wasn't suggesting you buy factory ammo. This is just a test that some people use to ascertain a relative pressure level of their handloads.~Muir

  5. #5
    Quote Originally Posted by Hornet 6 View Post
    So the damaged primers I found are likely to be caused by a fault with the rifle in question, over size firing pin hole, over strong firing pin spring etc ?
    Neil.
    A probable cause of primers pushed back out is excessive headspace in the rifle the rounds were fired in. Sloppy fit of unfired round in chamber. Firing pin pushes the case forward then the primer goes off igniting the powder & the case expands against the chamber walls effectively sticking it to the wall & stopping it sliding back. This leaves a gap at the back of the case head & the primer is then pushed out into that gap.
    This type of headspace problem also leads to "incipient head separation" which greatly shortens case life.

    Ian

  6. #6
    Quote Originally Posted by Yorric View Post
    A probable cause of primers pushed back out is excessive headspace in the rifle the rounds were fired in. Sloppy fit of unfired round in chamber. Firing pin pushes the case forward then the primer goes off igniting the powder & the case expands against the chamber walls effectively sticking it to the wall & stopping it sliding back. This leaves a gap at the back of the case head & the primer is then pushed out into that gap.
    This type of headspace problem also leads to "incipient head separation" which greatly shortens case life.

    Ian
    Cratered primers and backed out primers are different unless you Brits are using a different terminology than I'm used to. ~Muir

  7. #7
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    Are you certain that these truly are ONCE FIRED? You can get a backed-out primer (that is a primer that protrudes out the back of the case) if you just fire a primed but not charged case in most firearms that use a rimless cartridge. Damage to the extractor groove suggests that they were difficult to extract and that also would infer someone firing off primed but not charged cases.

    OTOH they may have been reloaded rounds. A crater on a primer can suggest either a oversize striker hole or firing pin hole or if looking rounded like a ring doughnut (that's "donut" for MUIR) but otherwise in the usual position you'd expect to see a primer in a fired case a very LOW PRESSURE.

  8. #8
    I'll let you guys hash this one out.~Muir

  9. #9
    Primers were cratered, not backed out, reseating just flattened the raised edge of the craters, the damaged rim was just a burr, would have been an easy fix but couldn't be bothered.
    As for only once fired (from many different rifles), I was told they were, and each and everyone had a ring of sealant/glue round the primer to brass join, not seen or heard of anybody doing that to reloads ?

    Neil.

  10. #10
    Hi Muir I agree pushed back & cratered primers are different - I wasn't sure what exactly the OP was meaning hence my post. Now Hornet 6 has clarified it so all happy now!

    Ian

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