volume weighing brass
- Thread starter rebel107
- Start date
I, too, shoot 1000yrd F-Class Open.rebel107 said:
Many years ago, I used to weight sort my brass, I would sort in 1gr +/- lots. I would still get some fliers within those sorted cases. I was confused by this and didn't figure it out for some time.
I started marking the cases that caused the fliers, weighed them with no apparent discrepencies and put them aside. Another shooter asked if I ever measured the cases with water, I didn't, so we did. The cases that caused the fliers ALL had differing case volumes, even though they weighed the same.
Long story short, there is NO DIRECT comparison to case weigh and volume, you may luck out and get similar volumes by case sorting by weight, but don't bet on it.
I take 10 cases from a batch, weigh them AND measure the volume in CC's, not grains of water. I use a 50/50 mix of water and isopropyl alcohol, it reduces the miniscus to almost zero.
(To those with QL, don't care that you use 100% water, it has no bearing on what I measure for MYSELF. This is how volume of combustion chambers is measured in engines, and is how I do it.)
Cheers.
You can use the 50/50 mixture, and multiply half of your weight per 1.27 (to report the alcohol's specific weight to water)
searcher
Gold $$ Contributor
I recently prepped several thousand rounds of 1X lake City .223 brass for use of varmint hunting. When swaging the primer pockets with my RCBS bench-mounted swager, I could feel that some of the cases were much more different when it came to how much resistance was felt when swaging. The rod that inserts into the case and rests against the inside of the brass to push the base against the swaging reamer would indicate that the amount of brass thickness from rod contact inside the case - to the exterior base of the case - was different from case to case. I pulled aside twenty of the worst offenders and, while half of them weighed within the normal limits of the rest of the cases, they all varied dramatically from the "non-offending" brass when it came to internal measurement. Granted, this was fired brass from different guns, two different year headstamps (full-length sized and trimmed) and not the perfect lab experiment - but the results were nevertheless repeatable with that brass. I will measure case volume and forgo weighing in the future.
Don't worry about the flash hole . Put a spent primer with bottom side up . Larryiron308 said:
To be exact, as a spent primer is what is also part of the combustion chamber, is what I use fired in that rifle the brass is to be used in. I also do not weigh, measure CC's or trim until it is fireformed to my chamber.iron308 said:
Once a load is found, tweaked, tuned or whatever, I then shoot for groups in new unfired brass to see if it is finnicky in any way, this generally tells if a load is very very good or not.
This is MY process, YMMV.
Cheers.
8)
I have an idea on how to build a device to measure the volume of a case with air, but I wonder if there is a big problem with case volume and the accurately of your reloads.
We do everything to make each round the same, but is case volume just another thing to worry about. 30BR case about 2.5 ml volume.
john
Mims,Fl
We do everything to make each round the same, but is case volume just another thing to worry about. 30BR case about 2.5 ml volume.
john
Mims,Fl
trpcboy said:
measuring case volume with air is viable since pressure and volume are directly proportional, but achieving it is not easy. Differential digital air pressure gauges (commonly called a manometer) that will measure to one thousandth of a PSI are available at reasonable prices, but connecting it to a case in a consistent physical location and getting the leakage out of all the connecting apparatus is a big issue. Ask me how I know. Also,even if you can achieve those necessary steps, you must conduct sorting in a carefully temperature controlled environment. Just hold any part of the connecting apparatus in your hand and watch the manometer pressure climb as body temperature heats the air in the device. The biggest issue is getting a consistent precise charge of pressure into the apparatus and case. Actually, a negative pressure charge (vacuum) works better than a positive one.
Chappy
Silver $$ Contributor
My next lot of brass, I'll will sort by what the chronograph tells me. With my new addition of the ADI FX-120I, load up to the single kernel in 300 cases and brings a couple buddies out for a range day. Sounds like I lot more fun than messing around with water volume measuring.
Chappy said:
I've heard of someone doing that before... firing every piece of brass twice, recording the velocities and batching the cases that way. Even had a second barrel chambered specifically for use as a fire-form barrel. They swore by it, but I'm not sure I ever ran across anyone else that was able to make the process work for them.
Good luck!
Chappy said:
I'm with dmoran on this one. Do you plan on cleaning the barrel between each and every round fired? And also attaching a temperature gauge to the barrel (available at McMaster-Carr) so that each shot is fired under the exact same conditions? And how accurate is your chronograph?
Chappy If the croney you use is off 2% that is only 0.06666 based on 3000 FPS. On a dasher I have found 1 full grain different in capacity that is 2.1276%. That should show on any crony . Larrymemilanuk said:
Chappy
Silver $$ Contributor
Nomad47 said:
I'm talking a Magneto speed and Oehler in use at the same time. Probably do 50 shots and clean, use some old brass to "foul" the barrel, go another 50. If it takes a couple days to do, that's perfectly fine. I plan on spending a day or two to test this method out. I damn near fried my brain with frustration trying the water volume mess. More trigger time of anything, mind you this is my F/TR rig.
PM me LarryChappy said:
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