Reloading for accuracy: case mouth flat spots

Reloading for Accuracy: How to deal with fired brass with flat spots on case mouth?

  • Toss brass with significantly out-of-round case mouths

    Votes: 0 0.0%
  • Flat spots on mouth has no effect on accuracy

    Votes: 7 77.8%
  • Use out-of-round mouth brass for fun shooting

    Votes: 0 0.0%
  • Fix your gun

    Votes: 0 0.0%
  • No idea, but am interested in the response

    Votes: 1 11.1%
  • I will comment with a useful comment

    Votes: 1 11.1%
  • I am treat sh*posting on NES like a full-time job, so I will comment with some unhelpful b.s.

    Votes: 0 0.0%

  • Total voters
    9
  • Poll closed .
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I could attach pics if needed, but I can't believe it's that unusual: after firing, maybe about 10-15% of my brass has a flat spot on the case mouth after a first-time fire of factory brass (ar15, WOA upper)

I was experimenting with different ammo, so maybe an entire box or two were a bit long. Or, Google suggests maybe I should try a different buffer weight, which I will try, as I have one I can vary.

But, I was just wondering what impact it might have on reloading them as a matter of course.

I've been tossing them thus far, but today I just decided to put them aside and ask opinions before tossing.
 
I get 'em almost D-shaped from hitting the brass-deflector (handy if you don't like chasing brass or bouncing them off the guy's head next to you) The sizing ball on the die rounds 'em right back out. Might effect case life, but so far no splits
 
If you are going for accuracy, what the brass looks like before you start the reloading process doesn't really matter (safety signs excluded). You will find there is a ton of prep work to make the cases identical, which will remove any imperfections your brass has.
 
I would tend to think that shooting them out of an AR, even a really good one, any really minor inconsistency in the brass isn't going to make a measurable difference accuracy wise. Too many other variables. Maybe get a cycle or two less before a split neck or something.
 
If I cycle my K31 aggressively, I'll dent the case mouth somewhat; figure it is due to hitting the receiver when forcefully ejected. If I extract gingerly there's no dentling at all.
Any minor flattening is rectified as the case/neck is re-sized.
Never detracted from my level of marksmanship.
 
Maybe its just me?
i find the AR to be pretty darn forgiving with regard to reloading and accuracy. Also accuracy is based on expectations. With that said, i think a dinged case neck/mouth/body will have little to do with results down range.

I say time for OP to do a test.
Take the brass you have been rejecting. Then load 10rounds of the rejected brass same you would brass that passes your rejection .
Now do a side by side test.
Here is how I might do it.
2 targets at 100 yards (point of impact is not important, dont chase zero ) take 2 factory rounds to warm up. i would pick a corner of the target backer on put them in the berm.
Then load your mags alternating your good brass loads and reject brass loads. label your targets and then alternate shots.
Lets see if any thing is different.
OP what are you using for ammo and reloading components.
You could play with buffers,BCG,ejector springs and such.
Case life is violent 2:40ish you can see some blown primers

View: https://www.youtube.com/watch?v=gD7pd03L43k
 
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Now do a side by side test.
...
OP what are you using for ammo and reloading components.

This is a perfectly good idea. I'm in the middle of working up 6.5 creedmore at the moment, and was just processing a bunch of old 223 brass when the question occurred to me to ask.

Generally, I'm experimenting with hornady match bullets (eld and regular bthp), and will be comparing vihtavuori/winch/imr. Fed primers. Rockchucker, rcbs competition dies. Brass processing is: universal decapping, lyman case prep express, stainless media tumbling, drying.

I'm just having fun at the moment: before I science the f*ck out of it, I'm still waiting for a part that was missing for my case master gauge, and I'm also awaiting a wilson micrometer trimmer to round it all out.

(One other purchase I'm torn on making is a length gauge. I might just borrow one, since - unless someone suggests otherwise - I don't think the headspace and barrel lands would change much, except predictably, over time: it's not like I'll be using the gauge that often.)

So, when I get to doing science on the 223 - maybe in a month? - I'll sequester 20 of the worst samples (D-shaped), and after putting it through the die, I'll take some measurements of case neck thickness on the best and worst brass, then reload and shoot it and see what comes of it.

Maybe I'll figure some way of marking the case on the side where the mouth was flat and see if that matters, but if it does, I figure it would show up in the gauge. I suppose there could be extra 'work hardening' at the corners of the flat which wouldn't show up, and might be relevant since I don't do annealing (yet).
 
This is a perfectly good idea. I'm in the middle of working up 6.5 creedmore at the moment, and was just processing a bunch of old 223 brass when the question occurred to me to ask.

Generally, I'm experimenting with hornady match bullets (eld and regular bthp), and will be comparing vihtavuori/winch/imr. Fed primers. Rockchucker, rcbs competition dies. Brass processing is: universal decapping, lyman case prep express, stainless media tumbling, drying.

I'm just having fun at the moment: before I science the f*ck out of it, I'm still waiting for a part that was missing for my case master gauge, and I'm also awaiting a wilson micrometer trimmer to round it all out.

(One other purchase I'm torn on making is a length gauge. I might just borrow one, since - unless someone suggests otherwise - I don't think the headspace and barrel lands would change much, except predictably, over time: it's not like I'll be using the gauge that often.)

So, when I get to doing science on the 223 - maybe in a month? - I'll sequester 20 of the worst samples (D-shaped), and after putting it through the die, I'll take some measurements of case neck thickness on the best and worst brass, then reload and shoot it and see what comes of it.

Maybe I'll figure some way of marking the case on the side where the mouth was flat and see if that matters, but if it does, I figure it would show up in the gauge. I suppose there could be extra 'work hardening' at the corners of the flat which wouldn't show up, and might be relevant since I don't do annealing (yet).
OAL length gauge came in handy for me loading the 80 grain bullets. As its to long for mag length loading I ended up .010" off before I lost time for load testing, my skills are more of a detriment of accuracy than anything else.
now with limitted time to shoot and test I load "close to known" accuracy loads and run with it.
 
This is a perfectly good idea. I'm in the middle of working up 6.5 creedmore at the moment, and was just processing a bunch of old 223 brass when the question occurred to me to ask.

Generally, I'm experimenting with hornady match bullets (eld and regular bthp), and will be comparing vihtavuori/winch/imr. Fed primers. Rockchucker, rcbs competition dies. Brass processing is: universal decapping, lyman case prep express, stainless media tumbling, drying.

I'm just having fun at the moment: before I science the f*ck out of it, I'm still waiting for a part that was missing for my case master gauge, and I'm also awaiting a wilson micrometer trimmer to round it all out.

(One other purchase I'm torn on making is a length gauge. I might just borrow one, since - unless someone suggests otherwise - I don't think the headspace and barrel lands would change much, except predictably, over time: it's not like I'll be using the gauge that often.)

So, when I get to doing science on the 223 - maybe in a month? - I'll sequester 20 of the worst samples (D-shaped), and after putting it through the die, I'll take some measurements of case neck thickness on the best and worst brass, then reload and shoot it and see what comes of it.

Maybe I'll figure some way of marking the case on the side where the mouth was flat and see if that matters, but if it does, I figure it would show up in the gauge. I suppose there could be extra 'work hardening' at the corners of the flat which wouldn't show up, and might be relevant since I don't do annealing (yet).

Here's a suggestion to help you shoot better.

Spend more time at the range and less time doing these science experiments.

Pick a powder, primer, bullet, follow some already established best practices and get out there.

Edit, also buy one of these (doesn't have to be RCBS) for every caliber you reload
RCBS Precision Mics - RCBS
 
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Here's a suggestion to help you shoot better.

Spend more time at the range and less time doing these science experiments.

Pick a powder, primer, bullet, follow some already established best practices and get out there.

Edit, also buy one of these (doesn't have to be RCBS) for every caliber you reload
RCBS Precision Mics - RCBS
What do you know! o_O
This is true unless of course a flyer is out side the X ring?
Some day clean cleans targets might be the norm for me.
 
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Spend more time at the range and less time doing these science experiments.

If the range I went to was open all night, this would be a coherent suggestion. It's not, so, it's not. [edit: Also, if I thought the experimentation was getting in the way of getting a good round count downrange, this might also be coherent, but that's also not true.]

I will look at those mic's.
 
If the range I went to was open all night, this would be a coherent suggestion. It's not, so, it's not. [edit: Also, if I thought the experimentation was getting in the way of getting a good round count downrange, this might also be coherent, but that's also not true.]

I will look at those mic's.
Look into the hornady case comparator set up. The RCBS are fine but costly
 
Remember that all your brass started life as a penny- sized flat disc. All that matters if what it looks like after it has been sized. I don't think you'll see any difference.
 
There are a handful of 223 AR shooters on here that have sub 1/2 moa rifles/ammo set ups
As for ARs when you get under 2moa and closer to 1moa and still think your your rifle/ammo/you can do better dig deeper and see where any inconsistencies lie.
 
I could attach pics if needed, but I can't believe it's that unusual: after firing, maybe about 10-15% of my brass has a flat spot on the case mouth after a first-time fire of factory brass (ar15, WOA upper)

I was experimenting with different ammo, so maybe an entire box or two were a bit long. Or, Google suggests maybe I should try a different buffer weight, which I will try, as I have one I can vary.

But, I was just wondering what impact it might have on reloading them as a matter of course.

I've been tossing them thus far, but today I just decided to put them aside and ask opinions before tossing.
No Pics necessary, unless it's causing the case mouth to crack, it's no problem. If it bothers you too much, do what I did when I was shooting my AR at long range matches. I shortened the eject pin a bit, my brass would just drop down in a pile. Long range shooters hate being hit by brass, they used to stick me on the end...Changing the springs will probably help as well.
 
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