................ is there a way of compensating for case volume difference with a very small change in load?
thanks
Bill Hodkinson
Rem 700 VLS in .308
Technically there is but it requires a scale capable of resolving single kernels of powder.
You sound like perhaps you are early in your learning curve, sorting out "what's important and what's not." If this is true you've come to the right place..... LISSEN to these guys, read every line and between the lines.
Which brings me to the thrust of my post.
My guess is that you're throwing your powder charges thru a volumetric measure or that perhaps you weigh some or all of your loads on a small balance beam scale, either of which are more than adequate for your setup. They ARE NOT however, adequate for resolving issues as minute as variation in case volume in cases of the same brand.
Nor is your rifle setup
You rifle is incapable of 'seeing' these small differences and looking to these differences will distract you from real differences, important stuff.
Some points to ponder;
#1, learning what's important is HARD. So take lots of notes.
Let me repeat.... WRITE IT DOWN!!..... every day, every outing, every reloading session. Get'cherself 6-8 cheapie ringbinders, I'm talking about 50 cent ring bound tablets from the local grade school supplier and WRITE IT ALL DOWN. Day/Date/Temp/Load/Gun/etc/etc/etc.... I even draw a liddle cartoon of nearly every group, just scribble dots and SWAG at a group size thru the scope....more data is better and you'll be amazed at what those groups show you over time. You want little round groups and vertical strings. Horizontal strings, diagonal strings, duck-shaped groups, turtle or elephant shapes, constellations and shotgun blasts, all bad but more importantly ALL DIFFERENT.
#2, believing what you're seeing is HARD, so take lots of notes.
Rabbit trails abound, innernet fables abound, opinions abound, learning not only the right questions to ask but from whom to get your answers is hard. Write everything down, keep an open mind and be honest. It's just too easy to believe that that one group you shot that one day is real.
It aint.
Even though there are billions of guns and guys on the net who "shoot quarter-inch groups all day when they do their part" they really exist only in their own fevered brains. Real, repeatable, on-call accuracy is not easily attained.
#3, now that you're WRITING IT DOWN you can assess for yourself.
This may seem trite but it's huge. If you've a question as to the efficacy of (sorting by volume/cleaning casenecks/reaming primer pockets/deburring flashholes/weighing VS throwing your charges/annealing/waxing VS dry lube VS wet lube/spinning-turning-folding-spindling-mutilating......and se...) you can test it yourself once you're WRITING IT DOWN!
And now you can make bell curves of things like velocity, velocity variation, group size and shape plotted against stuff such as brass weight variation, sizing variation, primer brand and type etc etc etc...
LISSEN but don't believe anybody.
Which brings me to the REAL thrust of my post. Powder throwers and balance beam scales.
You will read all sorts of stuff about how velocity is majorly affected by (case volume/neck tension/neck diameter/seating depth/bore cleanliness/primer seating/flashhole variation/brand of bore cleaner/brand of toilet paper the wife buys/brand of car you drive) when in FACT most velocity variation comes from how you measure your powder charges. If you've a scale capable of sorting brass to the tenth grain or better, do yourself a favor and check charge weights day-to-day, brand to brand etc, REALLY get a handle on your charge weight loading consistency and
eliminate charge weight variation as your first variable.
TRY this test and WRITE THIS DOWN
Check your thrower against a good scale.
The best powder thrower in the world is capable of throwing charges which consistently vary as much as a full grain of powder and the BEST THROWER coupled with the BEST TECHNIQUE coupled with the BEST METERING POWDER and operated by THE BESTESTMOST DUDE will absolutely vary 1/4 grain of powder in any given string and 1/2 grain from day-to-day.
This variation completely masks, completely eclipses any perceived variation from case volume differences.
IMO
I'm not saying not to ask the questions.... just be chary of pat answers and write your own opinions down and save them for future reference.
Enjoy The Journey
al
