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Variance in loaded ammo weights


rtp

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So, I'm a new reloader, and trying to do things as logically and safely as I can.

I've got a fair amount of 9mm range + personally used brass, tumbled, cleaned, and sorted by headstamp, with a majority of casings being F.C. which is Federal as far as I can tell.

I've ran numerous dummy rounds through the press to set/check OAL, and am loading low to mid-power 115gr using Hornady FMJ projectiles, 5.0gr-5.3gr of WSF and an OAL of 1.15" so far. I've checked every other charge weight, and am using the (progressive) press in turret/one round at a time mode to build my comfort level.

I weighed all components to be aware of expected variances. In the case of the Hornady FMJ, the 115gr projectiles have been within 1/3rd of a grain of each other so far, which seems pretty good..

I did a few additional sanity checks, weighing the completed rounds, and had a nice 'surprise' - I was seeing variations more than the charge weight + primer + bullet variance accounted for, +/- 5grains, which seemed...a lot.

So, I started to pull apart a handful, then weighed some of the empty cases and am seeing a fair amount of variation among all of the F.C cases - may be off on my numbers as I'm not in front of my notebook or scale, but it seemed to be +/- 6gr or so.

Is this expected? None are marked as +P, but it seems a fair amount of variance.

If I take various handfuls, some of them are nearly identical weights empty. Are different lots off by that much, or?

Were I starting from brand new brass (nearly impossible at the moment), what's the normal variation on weight, and am I wasting my time trying to weigh overall completed ammo weight as a sanity check altogether?

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@BeyondItAll

Not worried about the 1/3rd of a grain, am concerned about the weight difference in casings, as +/- 5 grains (not .5) could indicate a pretty unexpected powder load, if all other components were close to equivalent.

Better safe than sorry...I guess the lesson learned is don't trust completed weight at all, even if +/- 5 grains unless you have new cases within +/- 1gr..if at all.

?

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I've seen +-4gr in loaded ammo with same head stamp charge and primer, bullet etc. In mixed brass +-10gr is fairly normal. So I gave up weighing them when I thought I had a problem, I have what I call a mistake bucket and a practice bucket. The mistakes get taken down when I get low on bullets.

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I think it's excellent that as new reloader you are curious and asking questions. It pays to be anal in the reloading world, but like atbarr said worrying too much about the differences in weight of the loaded round is a bit too anal. You have to remember that all the minute differences in bullet weight, powder weight, case weight, etc, add up when you put them all together in the form of a loaded round, and would be a bit shocking if you've never seen it before. Good job, and keep being curious and anal.

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I have seen it lots of times, being cautious to this level will create mistakes rather than prevent them. Take it slow, relax, but follow common practice. Its there for a reason.

BTW, yes, common to have that much variance.

As stated above, the chrono and groups will tell you how accurate and consistant your loads are...enjoy!

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I use a lot of Federal brass, and basically there are two major types. One looks like machined brass, and the other one - if you look at the butt - looks kind of like powder metal. These are different in their weight by about 5-6 grains.

Within each group there are further variations, probably due to the particular plant making them.

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I have seen it lots of times, being cautious to this level will create mistakes rather than prevent them. Take it slow, relax, but follow common practice. Its there for a reason.

How so? I'd rather get some confirmation on what I am admitting I don't know, than 'take a guess' ? Let's face it, all the loading data we can find all needs to be interpolated to some extent, as even the manufacturers don't seem able to agree. ;) I'd thought brass within the same headstamp might be consistent enough for a final sanity check, but it seems not. Weighing up a bunch of FC brass seems to fall into a few 'groupings' of weight, so I wondered...why/is this normal?

I certainly appreciate the feedback, but I'm not trying to ignore common practice, just get some clarifications. ??

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I use a lot of Federal brass, and basically there are two major types. One looks like machined brass, and the other one - if you look at the butt - looks kind of like powder metal. These are different in their weight by about 5-6 grains.

Within each group there are further variations, probably due to the particular plant making them.

Thanks - this seems to be almost exactly what I saw - I can get a number of cases all the exact same weight, but there seem to be at least 3 (maybe two?) different 'groups' among a few hundred FC cases, up to 5-6gr difference, but within a 'group,' they're quite close..

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I have seen it lots of times, being cautious to this level will create mistakes rather than prevent them. Take it slow, relax, but follow common practice. Its there for a reason.

How so?

I am talking about being over cautious to the point of a fault. If you speak to a lot of people who have had squibs/double charges/etc., most are the ones who try to check the powder ever 10 rounds or some crazy number. They get tripped up along the way since you are getting out of rhythm and losing how the process should work. We are all creatures of habit and if you form good habits while reloading, that will carry you through. I had a squib when I first started reloading about 20 years ago. That was when I didn't have a good process and I was being too cautious. It's best to stay with common practice but take it slow and deliberate. Good habits will form from there and the comfort will grow. I'm not advocating that I'm the best reloader around - far from it. However, I have learned a lot over the years and when I hear of problems with reloads, I always look at their process. About 80% follow something like I mentioned above. The others are just distraction and misc issues.

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I have seen it lots of times, being cautious to this level will create mistakes rather than prevent them. Take it slow, relax, but follow common practice. Its there for a reason.

How so?

I am talking about being over cautious to the point of a fault. If you speak to a lot of people who have had squibs/double charges/etc., most are the ones who try to check the powder ever 10 rounds or some crazy number. They get tripped up along the way since you are getting out of rhythm and losing how the process should work. We are all creatures of habit and if you form good habits while reloading, that will carry you through. I had a squib when I first started reloading about 20 years ago. That was when I didn't have a good process and I was being too cautious. It's best to stay with common practice but take it slow and deliberate. Good habits will form from there and the comfort will grow. I'm not advocating that I'm the best reloader around - far from it. However, I have learned a lot over the years and when I hear of problems with reloads, I always look at their process. About 80% follow something like I mentioned above. The others are just distraction and misc issues.

Noted. :)

As a new reloader, I'm still trying to find that process. Part of that is going to include "change, and do this" or "do NOT do this."

I'd prefer to go slow and cautiously, as you said, checking charges and OAL every 10 rounds, on a brand new press and brand new reloader, and then get to the point where I decide how much faith to put into an auto-measure, OAL, and then making it every 25...50..100, etc., as well as 'don't bother weighing completed rounds.'

I'm not sure how else I can get there - I'm loading single round at a time on a progressive, and that weighing of charges showed me enough variation in charges that I took apart the PM, degreased it for the 3rd time, and am now hopefully going to see enough load consistency that I am not weighing every 5 or 10 rounds..

I may be chasing down the wrong path as an extra safety check of weighing the completed rounds, but what else am I doing 'incorrectly' here?

Note: Internet/web sucks as a way to gauge someone's demeanor and attitude - I'm asking the question sincerely - appreciate the help, just not sure what else to change?

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If you are loading one round at a time on a progressive, they won't be as uniform as if all the shell locations were filled. When all are filled you sort of equalize the pressure all the way around, not just in one place, off center.

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If you are loading one round at a time on a progressive, they won't be as uniform as if all the shell locations were filled. When all are filled you sort of equalize the pressure all the way around, not just in one place, off center.

+1

Also, watch the Brian Enos reloading video...lots of great information and it will get you going in the right direction. I think you are doing great so far but just trying to help out with things that I see will hinder you in the future.

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Instead of weighing single charges, do groups of 5 or 10 dumps. Get the average set where you want it and make 15 rounds with all stations full. Check your OAL and crimp on completed rounds 5 through 10. When your averages are where you want your ammo, make hundreds. Double check, if you wish, after three hundred rounds or anytime you leave the press overnight. I seldom need to make adjustments, even after leaving my press for weeks or months.

I understand the new loaders caution. We've all been there. The most important thing for peace of mind is seeing powder in the case when you place the bullet. If you do that you can shoot your handloads with confidence.

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One important point - when I load just the regular practice 9mm Major rounds I use mixed brass and never have any issues shooting them. I am sure there are some velocity variations, but they don't seem to matter much.

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+1 on all the responses to OP's original question, especially post#17 from Sroe3. When setting up my 1050 I don't count the 1st 2 powder throws, then I dump the next 5 throws in the scale and calculate the average. I also start low and slowly turn the adjusting screw only in one direction to start increasing my weight if I have to. If for some reason I have to turn back the set screw because I went to far, I go further than I have to to compensate for thread backlash and again start working from low to high.

As has been said keep your eye on the case right after the powder drop station and just make sure there is powder in there. You will eventually get very good at spotting something off about the throw.

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hi rtp,

attention to detail in reloading is good.

what you are expecting from the process may lead you to think

others are not attending to all the details as they should.

the bullet maker is +/- .3 grains. ok.

the powder should be +/- .05 grains ...

the cases.... weeeelll they vary a lot.

but unlike the bullets they are not sold by a weight specification.

so if you want to weigh ammo for meeting your specifications,

you will have to weigh the cases before you start loading them.

my understanding is that target rifle shooters do all that.

I read they are looking for matching case volume as much as anything else.

The good news is that you will know you have properly loaded ammo.

All that takes is more time.

pistol shooters use 10 times the ammo of target rifle shooters.

Since pistol accuracy is far more a question of handling the pistol and

not the accuracy of the ammunition, the case is not a big factor.

the time spent weighing is not productive in improving the resulting

holes in the targets.

I'd use the spare time dry-firing.

miranda

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Trust the press, trust your eyes. Stop loading as on a single stage press. Don't weigh completed rounds. Weigh bullets, but only a handful in a new box, to verify that what you have is what you bought. Drop the first 3 powder drops back into the hopper before loading or weighing charges. Weigh 10 charges at a time and average. Calibrate your scale every time before weighing charges. Visually verify the powder drop in every case as you are reloading. Once you start using the progressive press as intended, DO NOT pull cases off the press to weigh the powder charge or measure the OAL. Wait till the round comes out of the machine in normal operation, then pull the bullet if you want to weigh the charge. Look up occasionally to the powder hopper to verify that it is better than half full. If it isn't, add powder. Get a low primer sensor, or visually check the primers occasionally. Wear safety glasses while reloading. Turn off the radio or tv while reloading. Don't go a drinking binge and reload ammo. If loading bare lead, wash your hands with a lead dissolving soap after loading, or wear disposable gloves. If loading bare lead, every 1k rounds, take your seating die and crimping die apart and clean the lead out of them. Lubing the cases, although not necessary with carbide dies, makes loading much easier. Don't try for perfection in a reload....it's not possible in a bench mounted press...there are too many variables. If the press gets hard to deprime or move in any way, don't force it. Stop and investigate what is causing the issue. When the issue is resolved, empty the press of all the rounds currently on it, put them in a jar/bucket to be pulled later, then start over. Put your completed ammo in a box, label the box with the recipe and OAL. Put a label on your powder hopper that says what kind, what the charge weight should be, and what lot/date the powder is. Label your tool head with bullet type, size, and what OAL the dies are set up for. If emptying the hopper (changing powder or just emptying to store), manually work the powder measure to get all the powder out of it.

Edit to add:

Ask questions if you aren't sure of something, someone on here will know the answer.

Edited by GrumpyOne
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If you are loading one round at a time on a progressive, they won't be as uniform as if all the shell locations were filled. When all are filled you sort of equalize the pressure all the way around, not just in one place, off center.

I'm assuming this applies mainly to OAL and resize operations? Will it impact powder drop weights as well?

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  • 7 years later...
1 hour ago, Merlin1953 said:

I am reloading 115 grain  9mm ammo.  Finished weight of a cartridge is normally 177.0 gr.  Periodically I get 180.0 - 184.0 grains.  Is this acceptable?

 Really old thread. 
 

Moral of story, range brass can significantly vary in empty weight. 

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