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Discussion Starter · #1 ·
I noticed that after Full Length resizing and checking the headspace on my brass one by one all the headspace readings where inconsistent. I know consistency is key for accuracy. I use a hornady headspace gauge zeroed to a GO GAUGE 1.630 as TonyBen mentions in his video. My rifle is headspaced to 1.633 and I`ll adjust my rcbs full length die and size one brass to -0.002 to set my brass at 1.628. After setting my die and sizing some more brass I`ll taking some headspace readings and there where a lot of variations of readings I got. How do I go about fixing this or is this normal? I did make a batch of 60 rounds and they all grouped like crap.... Need help before I waste some more good brass. =)
 

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You should probably describe the equipment you're using in a bit more detail. What type of press do you do have? What type of brass was it? How many firings are on it? What type of lube were you using?

I have a lee challenger press and I find it difficult to get each and every case the exactly same, but they are all within spec according to my head space gauge. Some presses seem to be a bit more consistent than others, but that doesn't mean you can't make great ammo on a budget press. You also need to keep in mind that not all brass is created or shot equally so the amount that you're trying to bump the should back will vary from case to case.

As for the accuracy... a given load grouping poorly doesn't really say much. What was your load recipe? Crap bullets usually result in crap groups. Too much or too little powder will given the same result. A tuned super match will almost always outshoot an off the shelf standard. Long story short, tell us more so that we can help you. I doubt your minor headspace variances are main culprit to your less than stellar groups.
 
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Discussion Starter · #3 ·
I`m using a Lee 4 Hole Classic Turrent. I use Imperial Lube. First 60 batch of reloads where

Once Fired MKE Brass
CCI 34# Primer
IMR 4895 (Made 20 rounds of each Gains) 41gr, 41.3gr, 41.5
Blemish 168gr from Midwayusa
Brass Length 2inch
OAL 2.82
 

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I`m using a Lee 4 Hole Classic Turrent. I use Imperial Lube. First 60 batch of reloads where

Once Fired MKE Brass
CCI 34# Primer
IMR 4895 (Made 20 rounds of each Gains) 41gr, 41.3gr, 41.5
Blemish 168gr from Midwayusa
Brass Length 2inch
OAL 2.82
I use a similar load also with the Turk MKE and Nosler 168 blems. I can't imagine why you shouldn't have the same results. Unless the Midway "Blems" were some no name brand seconds? I remember couple years back Weidener's sold some "no name" blems that were absolute junk.
 

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I use a similar load also with the Turk MKE and Nosler 168 blems. I can't imagine why you shouldn't have the same results. Unless the Midway "Blems" were some no name brand seconds? I remember couple years back Weidener's sold some "no name" blems that were absolute junk.
I remember hearing the same thing about some midway blems, though I can't be certain yours are the same.

If it were me, I would buy some known quantity bullets, like Sierra, Hornady, or Nosler non-blem bullets and start there. Also, make sure the MKE brass holds a similar amount of water to an LC case because the 41.5 grains of IMR 4895 load is geared for LC Brass. If it's closer to Winchester brass capacity, you're going to have to up the powder charge about a grain to get similar pressure. The hornady bullets won't need as much powder due to their case bearing surface of their bullets causing slightly higher pressures for the same powder charge.

Finally, describe your rifle... and post photos of your groups.... some folks mistakenly think that sub moa loads in an M1A are common place. They aren't.
 

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Discussion Starter · #6 ·
Actually my first 60 rounds I did not use a Go Gauge to zero my hornady headspace and my brass was out of spec. May this be the cause of the bad groups ? Now since I have this GO gauge and I can zero it to 1.630 if there is variation in my headspace but it falls under 1.658 will it be fine and group well if everything else is correct ?
 

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Actually my first 60 rounds I did not use a Go Gauge to zero my hornady headspace and my brass was out of spec. May this be the cause of the bad groups ? Now since I have this GO gauge and I can zero it to 1.630 if there is variation in my headspace but it falls under 1.658 will it be fine and group well if everything else is correct ?
Way out of spec how? Too short, too long? I simply use a lyman case guage with groove cut in it and if my cases fit as it's supposed to, I haven't noticed an accuracy difference. A few thousandths one way or another shouldn't make a difference accuracy wise. It can and will make a definite difference in case life, but accuracy not as much in an M14.
 
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One final thing to try...

Baseline your rifle with a box of Federal Gold Medal Match ammo. If your rifle doesn't shoot that load well, it's probably got something wrong with it. Your rifle eats it up and spits out tiny groups, then it's relatively easy to clone that load.
 

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Discussion Starter · #11 ·
One final thing to try...

Baseline your rifle with a box of Federal Gold Medal Match ammo. If your rifle doesn't shoot that load well, it's probably got something wrong with it. Your rifle eats it up and spits out tiny groups, then it's relatively easy to clone that load.
Will do! My hornady headspace gauge reads 1.62 with a 1.630 Go Gauge, so my first batch was too short. Thanks for the helpful tips!
 

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Unless the cartridge headspace is so short that primer ignition is affected, then as long as the bolt fully closes and locks, the headspace won't have much effect on accuracy. Primer ignition affects how the powder burns in the case, so if some primers fire weakly that could give big changes in MV and accuracy.

And yes, it's typical for cases to resize with some amount of variation, due to amount of lube, nicks on the base of the case, etc.

Consider good accuracy ammo such as Fed GMM, it is made to work in guns with tight chamber headspace, and also in ones with more generous HS.
It consistently shoots very well with whatever rifle is being tested.

Jay Kosta
Endwell NY USA
 

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And yes, it's typical for cases to resize with some amount of variation, due to amount of lube, nicks on the base of the case, etc.

Jay Kosta
Endwell NY USA
I use a case gauge in combination with an indicator, surface plate and precision 1x2x3 block.



Measure enough cases, and you see the process variation. I was able to get the process set up and centered at about -.0025" from the longest allowable length (top of the case gauge), and this ran pretty well, none below the low limit, and none closer than .001" to the high limit; resulting in a .004" wide distribution.

Consistency in press operation, lubing, die to ram/shellholder alignment, and a host of other variables come into play.

Different case manufacturers required slightly different die set up to make the same process capabilities. I would hazard the hypothesis that the slight differences in brass types/thickness was the root cause for this.

I didn't plot normality, or histograms with standard deviations, etc.; as I was measuring 100% of the product.

YMMV.
 

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You are resizing something that may not be as precision made as you would like. There will be variations case to case in resized military brass or commercial. It can be hard to tell if the issue is the brass, reloading equipment, or technique. Make sure that variation from standard does not cause safety issues. No over length cases (HS or OAL) or high primers should escape the loading bench. The more you reload the more consistent you can become. Sometimes I see things that I should have noticed and corrected that I have been doing for years. Your 5 thousanths undersize is quite generous, I usually run mine at a minimum of 2 thou. under actual rifle headspace. If you are +/- 2 thou. then you will have cases that should always fit your chamber. At about 7 thou. undersize I tend to see the signs of stretching, this can happen when I shoot ammo loaded for one rifle in a longer HS'ed rifle.

John
 

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You should be able to keep things within about 2-3 thousandths variation. If you've got more than that, then look at a lube issue. The expander ball will pull the shoulder forward as KurtC alluded--you can minimize this by slightly lubing the inside of the case neck. I use Imperial case wax and drag my finger across the mouth every 2-3 cases. If the case squeals coming out, you're definitely pulling the shoulder.

Also, don't sweat the headspace tag on the rifle. Measure a handful of fired cases and size then back so you get on average 2-4 thousandths setback on the shoulder. That'll improve your case life.

At the end of the day, variations in the shoulder length is way down on the order of things that impact accuracy. The "consistency is key" mantra doesn't come into play until you're already shooting tight groups and working at long range. This includes case prep steps and charge weights. A tight rifle, with a good bullet and the right powder/charge should get you about a minute at 200-300yds without any of that fussing using standard low-end reloading equipment.

What rifle are we talking about here?
 

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When using either RCBS case lube or Hornady One Shot, my cases can range from 1.625" to 1.629" meaning the my average is around 1.627" even though I target 1.628." All I care about is that they are under 1.630." Even with this variation, I haven't seen much of a negative effect on accuracy in my personal experience.

With RCBS lube and a lube pad I've noticed that at first, when there's lots of lube on the pad, the cases will headspace shorter, but as the pad dries, the cases headspace longer. When I can't get 1.629" after two rams in the press, then it's time to refresh the lube pad.

With Hornady One Shot, I've noticed that at first, the cases will hit my target of 1.628", but the more cases I run, the easier it is to size them and the headspace shrinks to 1.625".

One thing you can try is to sort your finished rounds by headspace and shoot them in sorted lots to see if there is a difference in group size between matched and mix-matched rounds.

Tony.
 
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