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Reloading Techniques For Reloading


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How close is close enough?

 
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  #8  
Old 08-18-2012, 03:50 PM
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Re: How close is close enough?

thanks for the help guys.

Like I said in the first post I am a little anal. Just cant figure the variance in seating depth. Seems like with something that can be adjusted down to the thousandth, you should be able to get repeatability...



Bill
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  #9  
Old 08-18-2012, 05:32 PM
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Re: How close is close enough?

tolerances in the Ojive, the higher the mass production the looser those tolerances will be. It's just the nature of the beast.
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Keep in mind the animals we shoot for food and display are not bullet proof. Contrary to popular belief, they bleed and die just like they did a hundred years ago. Being competent with a given rifle is far more important than impressive ballistics and poor shootability. High velocity misses never put a steak in the freezer.

Joe
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  #10  
Old 08-18-2012, 06:04 PM
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Re: How close is close enough?

Whether it'll affect your results depends on things unknown to me(but still existing).
Once you've actually tested for best seating with a couple guns you'll come to recognize that 5thou CAN have a big affect,, but then it might not.

My seating does not vary by even 1thou. It is for the most part -exact.
My shoulder bumps are also pretty damn close to exactly 1thou, to begin(settle variance can shift ~-.0005 over time).
So I know that it can be done & how to do it.

I also know what mungs it all up:
-Not qualifying ogive radius
-Not using inline die seating(with an arbor press)
-Not turning necks to same thickness
-Not trimming necks to same length
-Seating bullet bearing too near neck shoulder junction
-Big variances in bullet bearing
-FL sizing necks
-Over cleaning
-Over annealing
-Over sizing
-Inconsistent/bad mouth preps
-Bullet mismatching seater plug, bad contact angles, bottoming, or contacting too high on nose
-Inconsistent neck lube
-Inconsistent/Poor measurement

You're probably thinking this is ridiculous, but with only a few more items added you can also address runout, headspace, capacity variance, and ES.
This allows for better quality in load development.

Anyway, test for best seating with your load, work down this list, & decide how and where you should go with it.
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  #11  
Old 08-18-2012, 06:41 PM
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Re: How close is close enough?

A few things that I've noticed that result in inconsistent OAL when measured from the ogive:

dirty necks (inside of course)
mixed brass (diff mfg and/or diff number of reloads) both should be avoided
bullet bases that touch or compress the powder in the case when seated
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  #12  
Old 08-19-2012, 05:01 AM
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Re: How close is close enough?

For hunting loads, .005" variance is fine. Competition loads should be not more than .001" with CUSTOM bullets. Hunting bullet ogives can vary a lot. And as others have stated, there are numerous fixes.
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  #13  
Old 08-19-2012, 08:46 AM
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Re: How close is close enough?

Amont all the topics and facets of reloading, the one that, to me, seems to have the greatest range of beliefs, opinions, importance and all that other "exacting" stuff is where on the cartridge axis should bullets be seated for absolute consistancy in how far they have to move to the lands when fired. Consider the following......

All the jackets used in making a batch of bullets don't get shaped to identical dimenions in the final stage of manufacture where the front part's sized to a point; they all don't have the same distance from their tip or some other small diameter near it back to some diameter on their ogive back where the rifling first touches it.

All the bottleneck cases headspacing on their shoulders don't have the same head-to-shoulder dimension; that tolerance effects how far the seated bullet moves forward before it touches the rifling because the case shoulder's hard against the chamber shoulder when the round fires.

All bottleneck cases headspacing on their shoulders have their shoulder set back a thousandth or more by firing pin impact; that changes the bullet's jump-to-rifling distance when the round fires.

When all these variables add up, they'll make the bullet's jump to the rifling vary a few to several thousandths. It'll never have zero tolerance as long as bullets are seated some distance off the lands. Does that make a difference accuracy wise? Maybe; maybe not. Shoot some 20-shot groups to find out. I've seen rifles shoot sub 3/4 MOA at 1000 yards with bullet jump spreads of 5 thousandths. Even semiauto service rifles used in competition have shot under 2/3 MOA at 600 with a 7 thousandths spread in bullet jump as well as up to 3 thousandths runout.

The only way anyone (in my opinion) will get zero spread in bullet jump distance is to use a light neck tension on bullets then seat 'em out far enough to be pushed back into the case neck when chambered and fired. Regardless of all the other tolerances in places mentioned earlier, this method eliminates all of them.

Too bad there's no bullet seating die for rimless bottleneck cases that uses the case shoulder as a reference instead of the case head. That would remove one of the variables.

Last edited by Bart B; 08-19-2012 at 10:18 AM.
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  #14  
Old 08-19-2012, 10:13 AM
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Re: How close is close enough?

What kind of bullets are we talking about? I have always found bergers to be real close and easy to get back to back numbers, sierra a little more slop, nosler a whole lot more slop.
Seating depths have a node (for lack of a better term) if those low single digit discrepancies show significantly larger groups, you may be right on the threshold of one and may need to go in or out a couple thousands to settle down in the middle. I use to fight this with some "hunting" bullets but not usually with the match bullets.
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