View Single Post
Old May 6, 2012, 07:17 AM   #26
Bart B.
Senior Member
Join Date: February 15, 2009
Posts: 6,318
oldman's FCSA example of what annealing necks each and every firing to maintain consistency between loadings does for accuracy:
The small group record for FCSA of 5-shots under 2" center-to-center at 1000 yards was on brass loaded 47 times, annealed each and every loading. Must be something true about the process.

Chose your answers wisely - some will tell you I'm all wet - others will have their specialty answers - you do the research, make your own decisions, and learn from them.
Well, I did the research and made my decisions. Maybe you should learn from them.

Note that this record is the smallest 5-shot group shot ever fired by the record holder in FCSA competition. All the others are larger; how much is hidden from public view. It's another example of statistical luck. But such is the way it is for competitive group shooters.

If you check out the FSCA web site's record page, you'll see that 5-shot record holder also holds the 6 five-shot group aggregate record (average of six 5-shot groups) of 6.4 inches in the heavy gun class. The light gun class record of 5.823 inches was set that same day by someone else. And the 5-shot record holder shot another aggregate record of 5.417 inches aboiut 5 weeks later. Those aggregate records hold single groups larger than the average; typically up to 50 percent larger. So that single 5-shot record holder's anneal-every-time process in FCSA competition must not have done all that well overall. The rifle's ammo shot groups on July 4, 2009 ranging from 1.955" up to somewhere around 8 inches or more. How much consistancy does his annealing every time really produce? Unless the largest 5-shot group sizes are known, it's impossible to tell. For all we know the guy who holds those records may also have fired the largets single 5-shot group of all. I really don't believe there's anything true about the process; the records back me up. We don't know what the average 5-shot group and largest group sizes are for all groups shot for the life of the barrels used. We only know about the smallest ones.

Some years ago, a friend clamped his Win. 70 based .308 Win. match rifle in his machine rest, took one new Federal brass case, loaded it with max powder charges of IMR4895 under Sierra 168 HPMK's 57 (yes, fifty-seven) times putting all bullets into about 3/10ths inch at 100 yards. That one case was full length sized every time and never annealed once in the tests. The die's neck was lapped out to about 2 thousandths less than a loaded round's neck diameter. Bullets were seated out to be set back a few thousandths when the round was chambered. The chronograph showed muzzle velocity spread was under 25 fps with metered (not weighed) powder charges.

Last edited by Bart B.; May 6, 2012 at 07:37 AM.
Bart B. is offline  
Page generated in 0.05113 seconds with 7 queries