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LR Mag Primers v LR Standard

Discussion in 'Handloading and Reloading' started by GJeffB, Nov 12, 2020.

  1. GJeffB

    GJeffB Member

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    Posted here first ... because

    I try to pride myself on research. We've all discussed substituting components, and i received great help with substituting Large Pistol Magnum primers for Large Pistol standard. Thanks. Now, to continue hammering the horse ...

    LRifle primers are really hard to find. Thanks to the community my .45-70 Cimarron Sharps 1874 is on the way and I can gather everything except LR primers.
    I emailed Winchester, CCI, and Federal asking if I could substitute LR Magnums in a pinch, with appropriate reductions. All responses were the lawyer safe "no, you must not deviate." OK, fine.But I searched the interweb pretty thoroughly. The vast majority of various forum answers to the question was to the effect "back down 10%, no problem, work up from there, I/we do it regularly ..."

    I'm not looking to sue anybody. I'm looking for actual experiences, please. Then there's the "in cold weather best to substitute magnum primers."

    Background: loading handgun calibers since 1960's. Some bottlenecks 10+ years ago. Back into .45 colt, .45 acp, .38/.357. Straight walls. I realize .45-70 is tapered, lubed, etc. Got it. Bottom line: safe loading practices. Light/staring loads in .45-70 falling block, H4198 or AA5744. LR primers unavailable, is substituting LR Magnum acceptable on an ad hoc basis?

    Thanks as always. You may find same/similar post elsewhere

    -jb
     
  2. JPIMBO

    JPIMBO Member

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    Winchester LRP for standard and magnum loads are ok for everything. If you are being safe and reducing by 10% they should be ok especially in a large capacity case. If LPPM are ok why not. This is a time of experimentation unless you want to quit shooting. So try a few and check for pressure. Then you will know for sure. Just make do.
     
  3. Charlie98

    Charlie98 Member

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    The cold weather reference is likely from ball powders, which can be hard to light consistently in very cold weather... pistol or rifle. The 4198's and AA5744 are not ball powders, but I don't see why you couldn't reduce and rework with those powders. Both of those powders provide decent case fill.

    FWIW, if I can't find any LR primers soon, I'll have to substitute CCI #34 arsenal primers for my .45-70 and other LR cartridges... also a 'magnum' level primer.
     
  4. GJeffB

    GJeffB Member

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    Thanks. As I pretty much expected.

    Charlie, the CCI #34 is listed as "Mil-spec" specifically for 7.62, and described as a Large Rifle size. Do I understand it's particularly harder, ostensibly to avoid slam fires in military semiautos? If not, what differentiates it (and it's cost)?

    -jb
     
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  5. Blue68f100

    Blue68f100 Member

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    The mil spec primer have a different anvil to make them less sensitive. It's also know to have a mag class primer compound. Far as I know the caps are the same thickness.

    Mag rifle primers are about 0.010" taller than a std LR primers. So they will sit high in a non mag primer pocket.

    Edit to clarify which primers.
     
    Last edited: Nov 14, 2020
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  6. blue32

    blue32 Member

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    I began using CCI 250 in cast rifle loads a month ago with Unique and 2400 after CCI 200 ran out. I haven't seen any pressure problems or changes in point of impact.
     
  7. Charlie98

    Charlie98 Member

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    Blue pretty much covered it. CCI is known to have probably the hardest primer cups, anyway, as well. Normally, they aren't much, if any, more expensive than standard primers. If you have a rifle that has light primer strikes, the CCI, and particularly the arsenal primers, probably aren't the best choice. I'm kind of curious to see if my Pedersoli 1885 will light them off.
     
  8. GJeffB

    GJeffB Member

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    Perhaps moot.
    Regardless or thickness, anvil, compound, or price ... all my usual online haunts show "out of stock." But more options are better than less. If you do get some, please report results, as I will if I need to go to magnums.

    -jb ;)
     
  9. Obturation
    • Contributing Member

    Obturation Contributing Member

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    I use mag primers for 45-70 . It's all I've ever loaded with because it's all I had on hand when I started loading for that cartridge , no problem. If given a choice I only buy mag primers because it simplifies life, never been an issue for me. Work up as usual.
     
  10. blue32

    blue32 Member

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    I'll add that using a magnum primer of any sort in place of a standard primer will add "x" more pressure. Of course, case volume / type, powder type and charge, fmj vs cast bullet neck tension, will all effect these variables to a degree that trying to develop a linear data set isn't possible for mass consumption. Deciding to take 10% off the charge weight is a common belief and I don't disagree with it, but I don't use it as a concrete rule. This is a great time for reasonable experimentation and I like to see threads like these.
     
  11. Charlie98

    Charlie98 Member

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    Looking at it from a simplicity point of view, I could see stocking Magnum primers only sounds like a good idea, but you might be missing out on some performance or accuracy. Granted, run what you brung, but if you are looking for accuracy, it can pay to work with standard primers, or at least give them a try.
     
  12. Laphroaig

    Laphroaig Member

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    I use LRM's in non-magnums when loading ball powders and reduced loads with less than a full case of powder. I have, on occasion, tested them with stick powders and never noticed much of a difference. If that was all that I could get I'd not stop shooting for that reason.

    I've never heard that. That would create an unsafe condition in free-floating firing pin guns, like Garands.

    https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/
     
  13. FROGO207

    FROGO207 Member

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    The only primer height difference is between LRP and LP according to what I could find. That said I have also gone to almost all my ammo using magnum primers. I just reduce a bit more and work up my load. Never a problem. YMMV
     
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  14. Walkalong

    Walkalong Moderator Staff Member

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    Yes, I’m sure they meant taller than a LP primer
     
  15. Charlie98

    Charlie98 Member

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    I've actually performed 2 informal tests with identical loads, only changing the primer. The one that surprised me the most was H335 in the 5.56mm. Most load data suggests SRM primers for the ball H335 powder, I got higher velocity and lower SD using a standard primer in both my 16" and 20" AR's. I did not test for accuracy, and I'll readily admit there are 10000 things that could have changed my results, including shooting for accuracy, compressed powder, a different bullet, or, in my case, how much coffee I drank. In the end, I still use arsenal (Magnum) primers in my AR blasting loads, but as I work up accuracy loads for any of my rifles, I give primer choice a little more consideration, now.
     
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