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

That's what I always talk about too. Its the finished product that is important. As far as brass you use. Lapua is excellent right out of the box. If you don't know how to properly prep your brass, then it is a good idea to buy Lapua. After all is said and done any good brass will produce great accuracy/precision if you prep it right. There's always a lot of talk about how accurate guys' rifles and loads are, but with no proof. Its always, you have to use this or that and I get sub 1/2 moa out of my rifle and load. Its all talk unless you can prove it otherwise. Also guys that don't check run-out have their heads buried in the sand and are driving blind. That chidt is going to sneak up behind them and bite them in the AZZ...

OK... so what's the best tool (s) for checking runout (both case & loaded)?... Been look'in at that sexy new redding slant gauge...

I don't shoot commercial ammo much. When I do I measure concentricity of every cartridge. Some are fine, up to 0.003". Others not so much. Many years ago like Mathman, I measured and sorted cartridges to shoot groups. I did this because prior to then I never paid any attention to concentricity figuring that any shot outside of groups I was shooting I must have pulled off at trigger break.

Cartridges with little runout grouped well, more runout groups opened up. Sort a group of cartridges where 3 had little runout, add 2 that had 0.010" runout, there were the fliers.

There is a mathematical relationship between bullet tilt and group size.... up to the point where the chamber bends it straighter.
This relationship depends on random rotational orientation of the bent bullet.

As I explained on this forum 4 years ago.
https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/12563531/re-collet-dies#Post12563531

I keep runout to 0.003 or less, it's not hard to keep it less than 0.003. I'd say most of mine are 0.002 or less. I also turn the necks as well to keep everything nice and aligned. It's is a PITA but since I started keeping case necks the same thickness and keep runout to a minimum, accuracy improved.

Honest question...at what yardage does a difference of 0.002" make in accuracy or group size?

Take for example 500 yards. Same case lot for powder - primer - bullet - and brass. Same rifle - shot same day - same conditions.

Shooter has sorted his ammo. He has 10 rounds at 0.002" runout - and 10 rounds at 0.004" runout.

How much of a difference will that .002" make at 500 yards?

I too would like to know what tools are used to measure AND correct runout. I want to start doing this....

Measuring is no indication that it DOES matter. Measuring ammo won't affect accuracy. First, you need to load it correctly.

There is a reason the the big dogs quit measuring; it is because it DIDN'T matter within reason and was thus a waste of time. Hell, before I ever knew I was supposed to measure it, I was shooting cleans.

Unless your process is terrible, your components are junk, or your equipment is junk, it is hard for it to matter in the grand scheme of things. Even a novice hand loader won't load ammo >0.005". I shot some factory Hornady into .25 MOA with 0.008" runout recently. I only measured it out of curiosity.

Unless it is TERRIBLY bad, it really doesn't matter. I used to check match ammo, but I also dropped the habit and saw no difference in scores. I haven't shot matches in a few years, but still shoot/teach long range shooting and use GOOD ammo when demonstrating in class. What matters more is keeping a rifle in tune.

Measuring for runout should be reserved for setting up equipment or when making changes to process or used as a diagnostic tool. Measuring each and every round is time consuming and the effort won't show up on target.

Correcting runout involves changes in process or equipment. The idea you can use a tool to correct loaded rounds is nothing more than a gimmick.

To measure it, purchase a concentricity gauge and dial indicator.

Some will measure a fired case to determine if their chamber is true. Then some will measure the neck after sizing...but do not fall into this trap as imperfections in the neck are pushed OUTWARD from the expander mandrel or expander ball. Personally, I prefer an expander mandrel or gauge pin to an expander ball. Sizing of the case and expanding the necks should be done in separate steps.

The true test of processes is to determine bullet runout. There is a debate as to where this should be measured; ogive, near the tip, or between the tip and ogive. Believe it or not, many times the runout found here can actually be bad bullets. Many claim they are getting 0.001" runout and maybe they are...but anything reasonable is OK. If you have a problem, the tool can help you identify which step is inducing it.

Could not agree more.

I’ve got to say your posts are what I was hoping for - many benefit from different positions taken from life experiences especially when the details are being parsed in a respectful way. Cheers!

Yes but imo knowing your ammo is straight is one hell of a mental booster.

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Yes but imo knowing your ammo is straight is one hell of a mental booster.[/quote]

Yes, and it eliminates one factor that often affects accuracy.

I might also mention that EVERY factor (including measurement) that's been discussed here is included in my GUN GACK books. They're definitely not The Revelation, because everything was learned from reading and talking with other handloaders, plus experience. And I continue to learn something just about every week or month.

But one thing I've noted before about the Campfire (and other Internet sites) is most people want some simple answer for free--especially relative newbies, many of whom have never even bothered to purchase a current loading manual, or if they have, never read anything except the data for the cartridge(s) they plan to reload.

That's a bit different than saying it doesn't matter. I don't measure every cartridge every time precisely because I know what a given batch of brass will do with a given set of dies with me as the operator.

Interesting thread.

I always strive for < 0.003 on both brass necks and bullet runout.

JB - I agree on all points - just interesting to hear of a similar opinion put into different words - for me, both resonate & make me a better shooter.

Good evenings to all!

Exactly.

Yeah, I lean to .0015.

Yesterday evening I loaded up some rounds for a custom barreled 270 Winchester that I am working up loads for. About all I can get are Hornady SST bullets right now for my hunting needs.
After loading I checked all of the rounds on my Sinclair concentricity gauge and found a couple were .008” out when measured just in front of the connelure. I had a hard time believing the necks were crooked because I used the Lee Collet die so I then reset the gauge to measure the case necks.
They were all within .002”.
I am now thinking that the bullet seating die is the problem as I was using the Lee bullet seater and it only makes contact with the tip of the bullet rather than further down closer to the ogive. I am going to pull the bullets and reseat with a RCBS seater to see if it makes a difference. If it doesn’t then it has to be the bullet jacket being thicker on one side I would think.
What I don’t understand is how can the bullet be that far off center of axis and it not showing up when measuring the case neck?