Case Weighing

[Fox Tales]

Hi All,

 It was suggested to me , to weigh new brass to help improve consistency. 

 My questions to those of you in the know are ;

    Should the cases be trimmed to a uniform length first ?

    Should the primer pockets be uniformed ?

    How would you bracket the weighed cases ?

 I'm sure this will be of help to a lot of fledgling hand loaders as well as myself .

 Thanks in advance .

        F T

[jcampbellsmith]

It's one of many suggestions made to confuse budding reloaders. I would ignore the suggestion and concentrate your efforts on putting bullets on the target.

Regards JCS

[bradders]

The AMU state that case weights are more critical with small capacity cases such as .223 than larger ones

"Here at the USAMU, we often weight-sort our Long Range brass (600 yards & beyond) with an eye toward uniform case capacity and consistent performance. Naturally, the weight increments vary depending on caliber, as a percentage of cartridge case weight. E.g., there's no need to sort .300 Win. Mag. brass as tightly as 5.56 brass. One less obvious benefit of this practice is to remove any occasional “outliers” – brass which weighs significantly more or less than the typical increments used within a given lot.

Several years ago, we sorted our virgin primed & inspected LC 5.56 brass into 0.3 grain increments. Given large Summer competition demands for LR ammo, we started with 50,000 to 60,000 cases of a given lot. We then winnowed them down into 0.3 gr. lots large enough for the team's Summer needs. (Why, yes, that WAS rather labor-intensive!)

We constantly conduct research to improve accuracy, and to improve efficiency without compromising accuracy or performance. We make no procedure changes without first fully verifying that performance will not be degraded. After significant full-distance machine-rest and shoulder-fired testing, we determined that we could safely increase the weight range of LC match brass lots to 1.0 gr."

[The Gun Pimp]

Many years ago, I visited and ammunition manufacturer.  Case-weight and its effect on m/v was one of my questions.

They were happy to show me a graph with two wavy lines on it.  It was the result of test-weighing thousands of cases and checking muzzle-velocity of same when made up into loaded ammunition.

There was no correlation between the two lines on the graph.  I've not batch-weighed brass since. 

But, it's one of those things - do it, if you think it could make a difference.  Some batch-weigh bullets, even primers.......

[Triffid]

From what I know, case capacity/volume is the important factor, not case weight. In the tests I've done, there is no relationship between case volume and case weight. So weighing cases is a waste of time to me.

If you want to go to those lengths, then measure the capacity of each case using water and batch them according to that.  

 

Triffid

[Reloader54]

"I've heard that if you sacrifice a chicken and dance round a bonfire at midnight, the very next day all your bullets go through the same hole"

[oak tree]

39 minutes ago, Reloader54 said:

"I've heard that if you sacrifice a chicken and dance round a bonfire at midnight, the very next day all your bullets go through the same hole"

You forgot to add you have to be naked when you dance

[VarmLR]

I only ever bother batching cases for my .223 target rounds because I have found that it makes a (positive) difference on load uniformity.  I do it by water capacity but weigh the cases with and without water to get an accurate idea of water capacity.  I haven't tried correlating empty case weight and capacity as it's the water capacity I'm interested in.  Cases first have primer pockets uniformed and all are trimmed to the same length (1.755" in the case of the .223).

I don't bother with the 6.5 or .308 because I've found it makes very little difference, especially as I normally use Lapua for the larger cals and it's pretty uniform to begin with.

[Reloader54]

38 minutes ago, oak tree said:

You forgot to add you have to be naked when you dance

the next time you see a tight group,, you will remember that statement.

[oak tree]

1 hour ago, Reloader54 said:

the next time you see a tight group,, you will remember that statement.

I am looking forward to seeing some good groups shot by some women

[Fox Tales]

 It would appear that JCS summed it up nicely .

 I did think this may be leading down the rabbit hole before I asked the question , though still feel it was worth putting out there . 

 I've got a chicken, might be waiting for a while before it's warm enough to dance naked under the moonlight .

 The water appears be less muddy now. It seems that any gains that would be made would be so marginal as to be of little interest, whether sorting by weight or volume. 

 Thanks all for your input and giggles .

   Cheers ?

[bradders]

You need to watch this video from the 18:20 mark and then see the relevance that you will gain more not from dabbling with parts, but from taking instruction and learning to shoot better.....of course, everyone is already the best shooter ever, well at least I am!

 

 

[Reloader54]

8 minutes ago, bradders said:

You need to watch this video from the 18:20 mark and then see the relevance that you will gain more not from dabbling with parts, but from taking instruction and learning to shoot better.....of course, everyone is already the best shooter ever, well at least I am!

 

 

agreed, and  if you wanna talk performance,,, talk real performance, not some hot hatch "chavmobile" 

 

DEFINITION OF ACCELERATION

One top fuel dragster 500 cubic-inch Hemi engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500.

It takes just .150 seconds for all 6,000+ horsepower of an NHRA Top Fuel dragster engine to reach the rear wheels.

Under full throttle, a dragster engine consumes 1-1/2 gallons of nitro methane per second; a fully-loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

A stock, Dodge Hemi, V8 engine cannot produce enough power to drive the dragster's supercharger.

With 3,000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. 

Cylinders run on the verge of hydraulic lock at full throttle.

At the stoichiometric (stoichiometry: methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.7:1 air/fuel mixture of nitro methane, the flame front temperature measures 7,050 deg. F.

Nitro methane burns yellow... The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.

Spark plug electrodes are totally consumed during a pass. After halfway, the engine is dieseling from compression, plus the glow of exhaust valves at 1,400 deg F. The engine can only be shut down by cutting the fuel flow.

If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half.

In order to exceed 300 mph in 4.5 seconds, dragsters must accelerate an average of over 4G's. In order to reach 200 mph (well before half-track), the launch acceleration approaches 8G's.

Top Fuel dragsters reach over 300 miles per hour before you have completed reading this sentence.

Top fuel engines turn approximately 540 revolutions from light to light! Including the burnout, the engine must only survive 900 revolutions under load.

The redline is actually quite high at 9,500 rpm.

Assuming all the equipment is paid for, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimate $1,000.00 per second.

The current top fuel dragster elapsed time record is 4.428 seconds for the quarter mile (11/12/06, Tony Schumacher, at Pomona, CA). The top speed record is 336.15 mph as measured over the last 66' of the run (05/25/05 Tony Schumacher, at Hebron, OH).

Putting all of this into perspective:

You are driving the average $140,000 Lingenfelter, 'twin-turbo' powered, Corvette Z06. Over a mile up the road, a top fuel dragster is staged and ready to launch down a quarter mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up through the gears and blast across the starting line and pass the dragster at an honest 200 mph. The 'tree' goes green for both of you at that moment.

The dragster launches and starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your eardrums and within 3 seconds, the dragster catches and passes you. He beats you to the finish line, a quarter mile away from where you just passed him. 

Think about it, from a standing start, the dragster had spotted you 200 mph and not only caught, but nearly blasted you off the road when he passed you within a mere 1,320 foot long race course.

...... and that my friends, is ACCELERATION!

 

speed, like accuracy  responds to "tuning"   but weighing cases to a beginner [and we all were one once] is akin like putting a go faster stripe on a clapped out  mondeo.  

 

[VarmLR]

3 hours ago, Reloader54 said:

agreed, and  if you wanna talk performance,,, talk real performance, not some hot hatch "chavmobile" .................

 

 

...........................speed, like accuracy  responds to "tuning"   but weighing cases to a beginner [and we all were one once] is akin like putting a go faster stripe on a clapped out  mondeo.  

 

Yep, agree whole heartedly.

Until someone new to the sport has a fair few rounds down the tube, there's as much sense in batching brass as there is in tapdancing in a glittery waistcoat down the aisle of your local Sainsburies whilst singing "those were the days" in Urdish.

As JCS rightly says...practice putting rounds on target, learning your drops, honing technique and reading the wind.  That little lot is enough to be getting on with for anyone.