Consistency, or lack thereof

Josh Umsted

Private
Minuteman
Sep 16, 2024
17
6
Ca
Been reloading .308 for a year, upgrading rifle and reloading components one piece at a time, pursuing consistent 1 MOA accuracy. Have achieved good to great results on occasion, but the only thing consistent is that my loads consistently turn to shit the next day.

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Shot these two groups recently, thinking I had it. Ive thought that before. There were 20 shots total, the other two groups a little larger but still under 1”. SD 8. ES 12. 20 shots. Avg velocity velocity 2640.

That was the last of the Varget jug. New lot runs about 40fps faster. Tried that, then went down from 42.8 to 42.2gn. Velocity was all over the place. Avg was close to targeted 2740fps. Groups were shit.

Well, I have 100 Lapua cases and maybe 400 Federal cases. Federal isn’t all the same lot and hasn’t been sorted by volume or weight. Maybe the universe won’t let me get away with that and wants me to get more Lapua.

Today, it was Lapua brass, 42.2gn Varget, SMK 168, CCI 210, and a pile of shit. ES 50. SD 18. WTF?

Compared that to what I thought was a good load from a few months ago with Berger 168’s, left over from a match. It wasn’t good. Big groups and big numbers.

Rifle is Remington 700 action, Criterion 24” light varmint, MDT Oryx, Nightforce NX8 4-32.

Reloading equipment is old RCBS rockchucker, charge master light, Redding full length sizing die set to bump shoulder .002”, Forster ultra micrometer seating die, and a 21st century expander mandrel. I trim every time with a Lee deluxe trimmer, if for nothing else, to chamfer the inner neck. On Federal brass it leaves a weird flange around the mouth of the case, which was suspect, and couldn’t be cleaned up with a hand deburring tool. On Lapua brass, no noticeable flange or weirdness around the mouth.

Recently started trying to anneal by hand, rotating case necks under flame until too hot for my fingers. It’s probably inconsistent and may be doing more harm than good. Neck tension and seating force feel much more consistent since using mandrel, Forster seater and annealing.

I suspect the Rockchucker is inadequate, but can’t imagine it’s the main problem. Haven’t checked concentricity. Why buy a gauge only to tell me my process is fucked? I dunno. Had faith the new Chargemaster was accurate, but will need to check that, too. My other scale is a super old Rcbs digital, so not sure how much that will tell me, if anything.

Gonna get a few hundred more Lapua brass to eliminate that variable. Haven’t tried all the bullets or all the powders. Haven’t tried all the expander mandrels. .3065 worked better than .306”.

If there’s anything obvious I could be doing better, feel free to point it out. I’m thinking a few imperfections are adding up to a big imperfection. Then there’s the human factor. I’m not a perfect shot but want my rifle to shoot better than me, and it doesn’t.
 
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A few thoughts.
  • Don't attribute too much (if any) correlation between ES/SD and 100-yard accuracy. I can get sub-MOA accuracy at 100 with bulk-loaded 69gr SMKs in .223/5.56 ammo with ES values in the high double digits.
  • There is no way that your press causes high ES/SD. I simply fail to understand why people think they need some special press to achieve consistent seating depth and concentricity. I use a '90s vintage Dillon RL550 and total induced runout (TIR) is consistently less than .002 inches. There's not a thing wrong with a Rockchucker per se.
  • With that said - are your primers seated deep enough and consistently enough? I discovered that, for some reason I still haven't figured out, the primer seating function of my RL550 refused to correctly seat large or small primers in any caliber rifle brass I loaded (pistol brass has never presented this issue). Primers were a thousandth or two proud (above case head) which led to TIR of .005 - .006 inches due to case misalignment with the die. Ammo still shot fine. But concentricity issues disappeared after I began using a Frankford Arsenal hand priming tool.
  • Can your brass move fairly freely in the press's shell holder? Again, not an obvious contributor to high ES/SD, but tightly-held cases may not be able to align with the seating die. You may want to invest in a concentricity measuring tool... $150ish from RCBS or Hornady.
  • Bad powder lot? Six months ago, I would have pretty much discounted the idea. I had used Varget for 6BR since I started the caliber, but I have gotten so disgusted with Hodgdon's pricing on Varget, H4350, and 8208XBR that I have gone exclusively to Vihtavuori powders. When I switched to N150 for 105-class bullets in 6BR, my ES/SD values dropped by nearly half (25-30fps ES down to 15ish). So powder made a difference for me.
  • Case prep:
    • You're not annealing if you can hold the case in your fingers. I've inadvertently tried to pick up cases that had been through my AMP annealer a minute or two before. Blisters. You need a machine of some sort.
    • Does your Redding size die use a bushing? If so, try adjusting its height so it stops a couple millimeters above the neck/shoulder junction.
    • What is difference between diameter of resized/mandrel'ed case and a loaded case? Bullet being held too tightly may be a thing.
    • How are you cleaning your brass? Inside of case mouth can be TOO clean imo. I use a dedicated tumbler with corncob media to remove lube; I have found velocity consistency improves if I tumble my resized brass in that relatively greasy media for 20 minutes. That seems to work even better than using graphite-based dry lube in the necks.
I don't know if any of these things will help. At the end of it all, I have found over several years that ES/SD values of around 30/10 give me PRS-match-level accuracy out to 1000+ yards in 6.5CM and 6BR, and 1/2MOA or better to 500+. Reloading .223 has been more challenging; the small case volume amplifies any consistency "blemish" such that I expect 40-50ish feet per second ES... and I still have no problem getting 1/2MOA accuracy to 500+ when the wind cooperates.

Good luck.
 
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I feel for ya, brother. It sounds like you're doing a lot of good things. I use a RCBS Rockchucker from the 70's and haven't been able to prove to myself that it compromises my precision rifle ammunition.

Your attempt at annealing didn't hurt anything and it probably didn't do any annealing either.

I didn't understand if you did something different with the case necks between those groups in the picture and your more recent results.

I would look into the following:
1. Check powder scale. Electric scales have a tendency to drift and may require frequent calibration

2. Check that the primers are getting seated completely. What tool are you using to seat primers? Are you using a different brand/type of primer?

3. If you can recall, try processing the fired brass the same way you did for the shots in the picture.

4. Are you doing something different in measuring the length of loaded cartridges? Are you measuring to the tip of the bullet or using a Comparitor to measure at the ogive?

5. I think you should be able to match velocity like you're doing. Aside from the lot-to-lot variation, the amount of moisture in the powder affects the burn rate and weight of the granules.

6. Only chamfer the case neck if you had to trim the case length.

7. Check the resized case length from base of case to the shoulder.


My brass prep for bolt gun is to clean the outside neck with fine steel wool, run a nylon brush in and out of the neck a couple times. Lube case with die wax, resize with 10 second dwell, then wipe wax off with paper towel. Check case length - only if you do trim case length, then chamfer inside and outside neck. You don't have to clean primer pockets unless it makes you feel better
 
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