Brass Prep Help

J

jd12

Guest
I have several questions I am hoping someone can shed some light on. A quick little background I am shooting a 260 remington, weight sorted remington brass, 142 smk, 42g. 4831sc powder, ccibr2 primers,I shoot between 600 and 1000 yards, here's the questions. This combination shoots very well but recently i have been trying to get my speeds in the single or low teen digits in hope of keeping vertical flyer shots to a min. Last week I took a small lot of same weight brass full length sized them, lightly neck turned to a thickness of .013 to clean them up for a finished loaded size of .290, expander them with a k-m mandrel, neck sized half of them with a .288 bushing the other half with a .287 and loaded them for today. Today I first ran 6 rounds through gun for fowling, then shot 15 rounds of a slightly heavier load combination i wanted to try. Now here is where I became completely baffled I shot 5 rounds of my normal combination of non neck turned brass through chrono for a 17 fps spred 2489 to 2506, next exact same load through neck turned brass with.288 bushing 35 fps 2530 to 2565, next .287 bushing 40 fps 2538 to 2578. Then i shot 5 more from the first standard batch (2552,2554,2552,2566,2554) .What am i missing why was the spred on the stand combo so much better and why did the same combo gain 50 fps at the end? Sorry for this being so long I just wanted to give everyone the most info I could in hopes of getting some answers. Thanks john
 
I also forgot to say it was 25 degrees today. thanks john
 
Sounds to me like the end result was attributed to some sort of fouling..Do you anneal your case necks ?

Dan
 
The brass i neck turned then tested was new and never fired , the standard load was fired brass. will new unfired brass be inconsistant in speed?
 
Could be fouling, barrel heat (did you let the barrel cool before shooting groups)?

Could be the chronograph (they are not that exact) depending on the brand.

Could be gremlins...:D

BUT, if you do figure it out, please let me know the secret...I haven't found the magic combo that gives me exact velocities every shot...

Wolfdawg
 
sounds like the neck tension on the std load maybe correct for your load, and the neckturned is not correct.
take the neckturned and try a reload wiht the same tension as the std load.
re shoot
 
Jd12

It is almost impossible to get consistant velocity spreads with new brass.Once it has been fired is when you'll get your good extreme spreads.If 17 fps is the best you can achieve by changing the powder charge try changing your primers next.
Also when you turn the necks on your cases you lose neck tension because your necks are thinner.To get more tension you would need a different bushing.
Lynn
 
You must log in or register to reply here.
Back
Top