I'm overthinking I believe

Discussion in 'Gun Project Questions & Gunsmithing' started by Ksmirk, Jan 12, 2020.

  1. Ksmirk

    Ksmirk

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    I've been looking at reamers for a 300WM I have that is getting a new barrel, the last chamber I just used a SAMMI spec and throated to get my FB..... it worked ok but not the best way to get there BUT it sounded like a good idea at the time. This rifle is for nothing more than hitting steel plates as I don't need the horsepower of that round for hunting so it's a single shot but the thing that has me scratching my butt is the neck dia. of the reamer, there are a mess of folks using this reamer with the ADG brass with great results but I'm old and have always heard that .002-.004" neck clearance is what is needed with no turn brass, this reamer has a neck dia. of .3395" and if my research is correct the ADG brass has a fairly consistent .015" thickness and when you add a .308 dia. bullet I get .338" which only leaves .0015" so I guess after this long winded question what are your thoughts? I think with all the great results it's kinda hard to argue with results but then again that old way of thinking has me questioning myself.

    Sorry for the long winded post but I'd like to hear your thoughts from folks that have a clue as in the past I've just used SAMMI min spec reamers but this one needs to be a little tighter. Thanks.

    Kirk
     
  2. BoydAllen

    BoydAllen

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    Some of the very best in short range use close to .003 for turned necks for 6mm. One very experienced long range shooter posted that a test showed no correlation between clearance and accuracy, meaning that from a proven rifle, less did not result in more. You want to have the cleanest possible bullet release. I would dimension my chamber for a real world clearance of .004 to .005 and pay a lot of attention to how much my die sized my brass, in diameter in the body, as well as the FB diameter, making it no tighter than the pressure ring of the largest bullet that I contemplated using.
     
  3. Dusty Stevens

    Dusty Stevens COVFEFE- Thread Derail Crew Gold $$ Contributor

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    Leave the math out and measure your neck over a loaded round. You can get a neck reamer to get more clearance or better yet skim cut the neck on the brass
     
  4. Ksmirk

    Ksmirk

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    BoydAllen that plays into my thinking from years back and the reason I am questioning, thank you for the reply..... at least my mind isn't fading lol

    Dusty I've been working in Quality for more years than I care to mention so it's a bit difficult to leave out the math and overthinking :) I have a few dummies that will be at Manson's shop for him to look over as well as the reamer print in question. While I really don't care much for turning necks this rifle probably wouldn't be too bad to turn necks.

    Thanks fella's!

    Kirk
     
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  5. Dusty Stevens

    Dusty Stevens COVFEFE- Thread Derail Crew Gold $$ Contributor

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    Give it a quick measure and see what you get over the biggest spot. Id sure be curious. Youll be better off in many ways to give those necks a good cleanup. You only gotta do it once!!
     
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  6. Daveinjax

    Daveinjax Silver $$ Contributor

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    I get better accuracy in everything I have been shooting by going to a minimum of 5 thousandths clearance and my 6.5 saum I’m running 7 thousandths. I’m turning my necks down to 12 thousandths from 16 thousandths the Norma 7 saum brass I’ve been using has. I’m annealing every firing also so necks don’t get brittle and crack from the work. I feel thinner necks and more neck clearance are a good thing. JMO.
     
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  7. Ksmirk

    Ksmirk

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    Dusty Stevens yea this won't be a high volume rifle so it may just be as easy to turn a hundred and go from there, I really don't feel like redesigning a reamer. The folks at Manson have always pointed me in the right direction over the years and nothing has been ground on just yet. I would take a measurement but I've not gotten the new brass in yet just a few hours of interweb digging.
     
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  8. Ksmirk

    Ksmirk

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    Well ended up deciding on a neck dia. of .342" that gives me .004" and my brother .006" clearance. Fella's I appreciate the opinions and direction on this! I get to thinking about things and just can't shut the mind down even when I know how things should be I tend to double think and end up chasing butterflies, thanks for getting me back grounded.

    Kirk
     

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