thick neck chamber

U

uspsamaster

Guest
On a savage 110 25-06 with the factory barrel and chamber I found the neck to be expanded to the point a bullet will drop right in on fired brass (.291" out side diameter with the Winchester brass I have been using) re sized brass has .282, .283 with bullet seated (does that mean I have .001 neck tension?)
Am I likely to see any accuracy improvements by using thicker neck cases from a necked down 270 (.285 with a seated bullet) or even a 280 (likely just slightly larger but unknown to me what dimensions it would have) or 30-06? How much clearence is required/ideal? will I be likely to have other problems if I get the neck too thick (not counting the obvious wont chamber or too tight to release the bullet)
 
Most fired cases will allow a bullet for that caliber to be dropped through the unsized neck. The only ones that won't are fitted necks for BR rifles which have from 1 to 2 thousandths clearance between the chamber neck and the neck of a loaded round.

I've tried thicker necked cases because I had a rifle with a large (SAAMI) chamber neck. Since it was a .243 and I had some .308 brass sitting around I necked some .308's down to .243 to try. It worked, but the accuracy wasn't improved at all, and was maybe worse. I gave up on using thicker necked cases, and after due consideration came to the conclusion that the thick necks produced enough variability in neck tension any improvement in fit was lost in the variability of the metal in the neck.

Even the best brass (Lapua) after sizing and firing will vary in hardness and consequently it's uniformity of bullet pull or seating effort.

Maybe the .270 brass won't hurt accuracy since it's only 0.001" thicker per side than the .25-06 brass, but that small difference probably won't improve case life which would likely the main problem with the large chamber neck diameter. The solution might be a new pre-fit barrel for your Savage if it really bothers you or you experience split necks after a few firings.
 
Thanks for the information, I would love to throw on a new pre-fit barrel but money is tight at my house so I will nurse it along (it is about time as I have also be doing some chasing of the lands and seeing accuracy drop off a little. Your answer is kind of what I expected as it introduces a bunch of new and somewhat uncontrollable variables. I do have split necks but only after many fireing and I suspect it is from work hardened brass. Thanks again.
 
You can save the necks for a while at least by annealing them. A propane torch and some care is all that's required.

I know about tight money too.
 
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