7mm Rem Mag Bushing Question

Discussion in 'Reloading' started by Special Delivery, Oct 6, 2011.

  1. Special Delivery

    Special Delivery Well-Known Member

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    I just spent several hours on the reloading bench and realized as I was about to seat my first bullet (175 SMK) that the neck was to large to put proper tension on the bullet. I'm using Redding Competition Dies and when I used the full length die it odviously expanded the neck. The Comp Dies did not come with any bushings, just said sold seperately. What size bushing do I need since I'm using a minimum spec 7mag chamber?
     
  2. Darcey

    Darcey Active Member

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    I shoot a 7mm also. As we know the 7mm is .284 caliber. Try going with a .282 bushing so your 2 thou smaller and see how the tension feels.
     

  3. Broz

    Broz Well-Known Member

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    You need to measure the neck of a loaded round with the same brass mfg. that you will be reloading . Take that measurement and subtract .002" to .003" and get the size bushing.

    Jeff
     
  4. Broz

    Broz Well-Known Member

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    This is incorrect. You have to take in consideration the thickness of the brass also. The correct bushing will be .284 + (case neckness x 2) - .002"

    Jeff
     
  5. Special Delivery

    Special Delivery Well-Known Member

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    Broz,

    I appreciate the input. The bushings range from .306-.314 and I have heard of this method from Reddings site, but with so many options I just wanted to know for sure before I order. Would it be better to subtract .002 or .003, I'm looking for best accuracy as this is a custom rifle that I will be shooting 1500 plus yards?
     
  6. Broz

    Broz Well-Known Member

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    To be honest, if you only order 1 bushing I would order the -.003" Reason is sometimes when I order a -.002" and if the brass is not really consistant on thickness I get a few that feel looser. For a hunting load a bit more tension is good insurance. But if you want to do some testing order a few sizes and test a bit. Or get the -.003 and see what you end up with.

    Jeff
     
  7. Darcey

    Darcey Active Member

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    Thanx for correcting me. Totally had a brain fart. I know better. Don't want to steer anyone wrong.
     
  8. Special Delivery

    Special Delivery Well-Known Member

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    Broz,

    Thanks a bunch man, I'll just get two in the sizes you recommended.
     
  9. backwoods83

    backwoods83 Well-Known Member

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    Here's a little more advice to go with that, if your developing loads when the temp is 60-70* out and it drops down in the 30s don't change your load if you get a good consist one, since your velocity and pressure will drop with the temp go from using a .003" under to using a .004" as the added neck tension should put you back where you were, just a thought, its what I do, I have atleast 3 bush for every comp die set I have.
     
  10. Special Delivery

    Special Delivery Well-Known Member

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    I've really never thought about that, just adjusted load for seasons. Seems smart though, it will increase the pressure to get you back up to speed.