Tony - I understand your theory - I am somewhat of a newby compared to a lot the the guys on this forum - not to firearms and shooting but to competion shooting - doesn't a "good n tight match chamber" solve some of the contricity problem?  I have an Eric Johnson bbld  and chambered gun and the Chamber is "tight".  If I can ever master readin the conditions its true nature will be revealed.  I have always thought that this "tight" chamber was necessary to align the case the slug and the bore - with ur gage it just lets u know what is straight and what isn't - seems like u just end up with an awful lot of practice ammo since there isn't that I know of a practical way to straighten the ammo other than a good-n-thight chamber.  Just my opinion. - respectfully - rimfire

Rimfire,

Ammo "straightening" in a tight chamber has been an accepted myth for a long time.  This myth has been perpetuated by a couple of the best rimfire gunsmiths in the US as the reason why you have to use "their" specialy designed match chamber reamer.  Several people have proven that this does not actually happen.  I have shown people repeatedly with one of our gauges that bullets do not "straighten" in tight champbers.  Easy enough to do if you have a precise machine to measure runout before and after.  You can prove it to yourself quite easily if you have a lathe.  Using the lathe to find a case with excessive runout like 0.003 to 0.005 runout, carefully chamber and remove and remeasure.  I believe there was a discussion of this on benchrest central where a guy chambered a round with excessive runout and then looked at it through a 30X microscope.  He commented that you could see how the rifling was engraved unevenly around the bullet.

Think of the problem in these terms.  A rimfire round is crimped into the case with the heel of the bullet inside the case.  Is it more probable that the soft lead bullet will enter the rifling crooked and be engraved unevenly or that the soft lead bullet will overcome the force and surface area of the crimp and be straightened.

These things being said, I agree that a tight match chamber provides the best accuracy, when combined with straight ammo.  Some of this is a little semantic because of the changes being made since our research has been published.  For instance, Remington approached us to dicuss our findings.  Unfortunatley they (as well as one other European manufacturer of premium ammo) have taken the easy way out.  A side conclution to our research was that loosely crimped bullet shoot better than bullets with 0.002" runout but not as good as bullets with 0.000" runout.  Both of these companies have clearly gone and done their own research to reprove what we learned and because they want "all their ammo" to produce the "best possible out of the box accuracy" have gone to loose crimps.  This means the bullets are free to move slightly in the case.  From their perspective I can understand why this is a good decision but it does not provide for the ultimate in accuracy combinations, that being a tight match chamber and bullets with 0.000" runout.  It is however beter than bullets with random runout ranging from 0.000" to 0.007" in a tight match chamber.  Hopefully this discussion answers your question.

There are to be two articles coming out in Presicion Shooting magazine about our product and independent results some time this year so be looking for more discussion on the subject.

Tony Nielson
Nielson Brothers Arms, Inc.
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Tony - thanks for ur input - just trying to learn and become more knowledgeable of the finer points of the competion shooting game.
Respectfully,
rimfire