Home Forums Hunting & Shooting Ask The Gunwriters Run-Out: what is allowable given different circumstances?

Reading the quote in the Rifle Magazine thread and saw Mathman share the typo relating to .03 or correctly .003 and MD’s assertion that number being ok for varmint rifles but not benchrest. Made me curious.

My question is - zero runout would of course be the goal but when does runout become a significant problem to accuracy? .003? .005? .009? I’ve got a case master and each set of dies seems to generate its own result. Is this a shared experience?

I don’t know as much as I should about this topic & would enjoy learning more.

Tim

I’ve always heard that a reasonable goal is .002 or less.

RCBS's directions for the Casemaster suggest .005 for big game loads, and .003 for varmint loads--but obviously those are only general guidelines.

Some of it depends on the bullet. I've found some are more sensitive to run-out, generally "softer" bullets, though in my experience that includes the Nosler Partition, due to the open rear end. "Harder" bullets tend to be not as sensitive, especially monolithics, I would guess because they tend to straighten out when entering the rifling.

Thanks, MD! I’ll be down cellar tonight rolling things around. Interesting thought on bullet hardness.

What can the rifle and shooter resolve? A good benchrest rifle can "see" differences that something like a well worn Savage 99 can't.

I had a friend who is good on the trigger shoot some runout sorted Lake City Match ammo through a good Sporter 308. He didn't know what he was testing so he had no bias. The groups clearly went to pot when runout got above 5 thou.

I don't think there is a magical number. Many BR and F-Class champions state they do not measure runout.

if your worried about accuracy and run out on brass used with a good rifle just buy Lapua brass its a lot less work in loading new brass or reloading your brass for accuracy.

^^^^right there^^^^ yes I can easily get my loads down to minus .003....but my lack of skill at the shooting bench pretty much makes it more about confidence in ammo...than results. If I fire a boo-boo, I know it's me, not my ammo. And I seem to fire a lot of boo-boo's.

Not measuring runout is no indication that it doesn't matter.

i shoot in the master division its not that of big of deal except i want people to understand this = > good brass is very important to shoot well . the only thing i do with my new Lapua brass for run out is weigh my new Lapua brass all 500 cases from the same lot number. and put them in piles so this new brass is with 3/10 ths of a grain in each pile . then load and reload same 50 cases over and over i may candle reneal those 50 cases after shooting them every 5 or 6 times ? medium powder loads is easier on brass life too ! i also always volume load so do most of the guys i know , matter fact one friend just won South Dakota 600 yard big shoot last fall 2021 with a 6 BR doing exactly this way with his brass and volume loading.

Thanks all! I appreciate all the perspectives shared.

Still not sure how I never thought to read the directions for my casemaster lol.

Enjoy your Saturday!

Question for clarity. Are we taking runout of brass only or loaded round here?

I was talking about the loaded rounds.

What is "volume loading"?

IME if your loading technique and equipment are solid < .003in is the norm. Only time that has not been the case (pardon the pun) is a 308 neck die that INDUCED .007 runout in every brass. Sent it back to the manufacturer and replaced it with a FL die since I now use LCD for most loading.

Recently my son bought a couple of boxes of Federal Premium 270 Winchester ammo loaded with 150 grain Nosler Partitions, a combo that normally groups well inside of 3/4" at 100 yards.
This stuff, though, had trouble staying inside of 2" at that distance. We thought something might be wrong with the scope so tried a group with ammo from an older lot which put 3 shots into a 1/2". So it's likely something to do with this newer lot.
When we got home I checked for bullet run out and was shocked to see it was running from 0.01 to 0.012" ( 10-12 thou!). The older lot showed run out from 0.002 - 0.003".

Federal Premium used to be very good. Anyone else experienced recent quality issues with Federal Premium ammo?

I agree. Anything over .005" TIR and guys that shoot well, will see a difference in group size. The reason I keep my loads less than .003". I always say my properly adjusted standard RCBS dies give me that. Sometimes even better. I like that more. I was checking my 22-250 loads the other day, since I switched bullets that are known to be troublesome (from some guys here) and run-out was less than .002". Checked some 6.5 CM loads and the run-out was all less than .0015 TIR. If I were a benchrest shooter, I'd strive for less than .001" TIR. A very long time ago a company called Brown Precision put out an article discussing run-out and how Chet Brown used his concentricity gauge to check and adjust run-out. He submitted his findings in that article and basically said the same thing as mathman. Anything over .005" and you could definitely see a difference in group size. One thing that I have to say in regards to concentricity: When testing for accuracy/precision, you really need to be shooting an accurate rifle to begin with. Testing with an SKS is going to get you no where. Testing with an accurate rifle (even an accurate hunting rifle), you'll see the effects of poor run-out vs. extremely small TIR readings.

Loaded rounds

I agree. That is a very good point about equipment. It is always a good idea to check your finished loads to make sure your equipment is adjusted properly to minimize run out. If equipment is not up to the task, get rid of it and replace it with something that gives good TIR's. For those that don't know, that doesn't mean you have to use benchrest seating dies or anything fancy. It just has to be consistent and produce the numbers you are looking for. With my ammo, I an not happy with anything that produces more than .003"

I think that’s where I’m headed too (.003). I was keeping things under .005 but now realize my window might have been a bit too wide.