Measuring Case Volume vs time-intensive case preps

[seymour fish]

That's the most accurate M14 I've heard of.

Seems unlikely to most. To add to your incredulity, 3 run the same load, with similar results. All built by a master to same specs. For state of the art, look no further than Bamban's accomplishments

 

[Bart B.]

Bart, my m-14's do the same,

308 Win ammo with a 3/10ths grain spread in charge weights shooting about half MOA extreme spread for 20 shots at 600 yards?

How was the rifle held and aimed? What sights were used?

I may learn something; if the answer's credible

 

[seymour fish]

308 Win ammo with a 3/10ths grain spread in charge weights shooting about half MOA extreme spread for 20 shots at 600 yards?

How was the rifle held and aimed? What sights were used?

I may learn something; if the answer's credible

 

[seymour fish]

Bart, no 20 shot strings. 5 shot groups, mild steady conditions, off a hart base with a Fudd adj width windage top, old bald eagle bag 50/50 lead shot and sand, wood top bench. No flags/ readingmirage. Bushnell scope. 1:12 criterion on forged receiver. Sure fire muzzle brake, chrome silicon springs, 155 scenar, H4895 mild load, 2620 fps, mag length, sadlack piston. Usual tricks re: gas system and bedding in 3 stages. Shuster adj gas plug effects part of the tune. Gas system must be kept carbon free or tune diminishes-at least every 100-150 rds. Set up for very mild recoil, and thus usable from many positions in the field. It is typical for friend with no knowledge or experience with these to hit a milk jug at 750 firspt shot, or a standing crosstie at 1000 on first shot prone/atlas, with dope call given. Tricks done on the gi fiberglass stocks to stiffen. Cheek pieces

 

[seymour fish]

Bart, no 20 shot strings. 5 shot groups, mild steady conditions, off a hart base with a Fudd adj width windage top, old bald eagle bag 50/50 lead shot and sand, wood top bench. No flags/ readingmirage. Bushnell scope. 1:12 criterion on forged receiver. Sure fire muzzle brake, chrome silicon springs, 155 scenar, H4895 mild load, 2620 fps, mag length, sadlack piston. Usual tricks re: gas system and bedding in 3 stages. Shuster adj gas plug effects part of the tune. Gas system must be kept carbon free or tune diminishes-at least every 100-150 rds. Set up for very mild recoil, and thus usable from many positions in the field. It is typical for friend with no knowledge or experience with these to hit a milk jug at 750 firspt shot, or a standing crosstie at 1000 on first shot prone/atlas, with dope call given. Tricks done on the gi fiberglass stocks to stiffen. Cheek pieces

1.632". Bump 0.002. Have one batch of cases fired 25 times, still shooting same standard

 

[Bart B.]

1 gallon milk jugs are larger than 1 MOA at 750 yards.

Set up 20 then shoot at all them firing twice a minute.

I learned you're shooting larger groups and shooting fewer shots

 

[seymour fish]

1 gallon milk jugs are larger than 1 MOA at 750 yards.

Set up 20 then shoot at all them firing twice a minute

1 gallon milk jugs are larger than 1 MOA at 750 yards.

Set up 20 then shoot at all them firing twice a minute.

I learned you're shooting larger groups and shooting fewer shots

no Bart, you have learned nothing at all. We have learned quite a lot about you. Twisting words to fit your agenda is a "tell". Not simply a lack of reading comprehension. Seems a sad way to remind us that you "used to be somebody", if you ever were, so tell us again, please

 

[Bart B.]

Yawn.......

Milk jugs subtend greater angles at 750 yards than 1/2 MOA, 3" subtended ones at 600 yards; they're much bigger. A 1/2 MOA angle subtends 3 inches at 600 yards, 3.75" at 750 yards. You haven't measure 750 yard accuracy with anything smaller than a milk jug; it's bigger than 3.75" across.

5 shot strings do not equal 20 shot ones.

I can tell the difference. Some people cannot and don't want to learn how to.

 

[Brians356]

T, the water method is all you need. Tap the case mouth a couple times on a board to knock out any loose carbon. Fill case to point of a surface tension lenticular bulge. If some runs over, no problem, mop it off the case with a paper towel.

If you are weighing a bulging meniscus outside the confines of the case, you are weighing more than case volume, and also adding variability - how bulgy is your bulge? I can create a meniscus so large it literally hangs over the outside of the neck.

PS

Before some advises adding alcohol to reduce surface tension - no need for that. Just fill the case, using a small pipette to add tiny drops, until the meniscus is mirror flat level with the case mouth. (The reflection of an incandescent desk lamp works well for judging "mirror flat".)

http://www.stewmac.com/Materials_an...esives/Applicators_and_Pipettes/Pipettes.html
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[seymour fish]

If you are weighing a bulging meniscus outside the confines of the case, you are weighing more than case volume, and also adding variability - how bulgy is your bulge? I can create a meniscus so large it literally hangs over the outside of the neck.

PS

Before some advises adding alcohol to reduce surface tension - no need for that. Just fill the case, using a small pipette to add tiny drops, until the meniscus is mirror flat level with the case mouth. (The reflection of an incandescent desk lamp works well for judging "mirror flat".)

http://www.stewmac.com/Materials_an...esives/Applicators_and_Pipettes/Pipettes.html
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Brian, I prefer to bulge. If you don't like to bulge......, suits me. The concept is repeatibility

 

[Brians356]

Brian, I prefer to bulge. If you don't like to bulge......, suits me. The concept is repeatibility

Repeatability, huh? You said a mouthful. So, how do you measure the bulge, accurately, for your cherished repeatability? Flat is flat. "Bulged" ranges from slight to hemispherical to hanging over the side of the neck.

Also, when comparing different cartridges, or different published capacities for cases, how do you relate your findings with published values based on the convention - to wit, level with the case mouth? Of what value is the weight of water residing outside the case?
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[seymour fish]

Repeatability, huh? You said a mouthful. So, how do you measure the bulge, accurately, for your cherished repeatability? Flat is flat. "Bulged" ranges from slight to hemispherical to hanging over the side of the neck.

Also, when comparing different cartridges, or different published capacities for cases, how do you relate your findings with published values based on the convention - to wit, level with the case mouth? Of what value is the weight of water residing outside the case?
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Brian, I anticipate splitting meaningless hairs with you. Let's consider that surface tension allows some amount of bulge, but not what it cannot support. Leaving surfactants out of it, a bulge gets only "so big" before water runs over. It seems to me easier to be sure cases are filled the same with practice using this method, and easier for me to see an under fill and correct it. Do I sense you are emotionally Triggered here, with your "cherished" comment, but if it will cause you no harm, we can continue. There are 2 concepts in play 1) standardizing case volume too eliminate a source of error 2) backfilling more accurate numbers into quickload to select best powders, best loads projected buy barrel time, as well as picking a starting load. I find success using my method. Your desire to create distraction from the central tenet of the post, that Matched fired Case Capacity is desirable.

 

[Brians356]

Do I sense you are emotionally Triggered

You'd know best about that. Are you that sensitive?
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[Mozella]

Ron Blain's chart is interesting, but they say a picture is worth a thousand words. So I took his data and turned some of it into a chart.
Case Weight vs Case Volume

It shows in a pictorial way case weight vs case volume for each of the five different brands of brass. Several things are easier to see in chart form than in tabular form. For example, the more a particular line is spread out from left to right, the greater the variation in case weight. The greater height of a particular line, the greater variation in case volume.

If variations in case volume are important to precision, then the WCC 10 or Federal would seem to be the better choices.

I put a trend line on each brass brand. The flatter (more horizontal) the line, the less the case volume varies with weight. A steep trend line, like that shown for the LC 13 brass means the volume varies a great deal with weight. One might argue that sorting Federal brass by weight is a waste of time while sorting LC 13 brass by weight is mandatory, assuming case volume means something.

Notice that three of the brands show less volume with increasing weight. Two brands are just the opposite; i.e. the heavier the case the more water it holds. I'm not going to guess why mainly because it doesn't make sense to me at first glance.

The chart also shows that, generally speaking, the brands which are heavier hold less water. That makes sense, to me at least, because it seems that cases which have the same external dimensions should have less volume if they're heavier as long as they're made from the same material. Of course, the way the base is made could have something to do with the weight without necessarily effecting the volume of the case. Talk among yourselves.

I'll leave it to forum members to argue about what all this means, if anything.

 

[Brians356]

FWIW - I weigh powder on a high end Mettler analytical balance to +/- less than half a kernel. That is far finer an increment than is necessary, most definitely gross overkill. However, the manner in which I dispense and weigh powder is such that weighing to +/- 10 kernels would still take me about the same amount of time, so I've always figured why not take it out to a level where I'll never, ever, ever have to worry when I'm on the firing line at a match that I could have weighed my charges to a finer degree of precision. If it took me ten or twenty times longer to measure powder to that level, I wouldn't be doing it.

I think in general most everyone has their particular reloading practices, some of which may fall into the uber-OCD overkill category. That's ok, being extra careful only slows things down. Not being careful enough will often cost points.

FWIW Virgil King found keeping charge weights within +/- 1 grain was adequate for his purpose (shooting consistently in the "zeros" indoors):

Powder charges, as long as they were fairly consistent and bracketed within a couple of grains, were not important, he said. On one occasion, as an experiment Virgil shot one group with his 6PPC barrel on the Cooper action using a 53 Culver setting of Winchester 748, the next 52 and the third 51. All three groups were identical.
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[terraMODA]

No issue except it is time consuming to do in an quanity. I used a 50cc syringe and fill from the bottom to prevent air pockets. Best to resize first leaving the spent primers in the cases, then remove later.

I was told it's best to measure case capacity on fire-formed, unsized brass since that will be the volume when it's shot. Especially with the larger cartridges. That's the way I do all my 308 brass and 300 winmag. I use quickload to develop loads and it seems more accurate to me when I measure this way. And trust me, 300wm case capacities can vary a lot between manufacturers!

 

[Twoboxer]

I was told it's best to measure case capacity on fire-formed, unsized brass since that will be the volume when it's shot.. . .

Quickload's pdf manual says to use fired unsize cases for most rifle calibers and other guns using pressures above 30,000psi; use sized cases for the others.

 

[terraMODA]

Quickload's pdf manual says to use fired unsize cases for most rifle calibers and other guns using pressures above 30,000psi; use sized cases for the others.

Makes sense as the higher pressure tends to fireform the brass, whereas the lower pressures... not so much.