Seated bullet runout---real world practicality

[Lucky Shooter]

I know we'd all like to truthfully brag about getting "zero" runout but what is honest practicality ?

In the quest for serious BR accuracy, how much runout can we tolerate before we call for help ?

I realize there are no firm and unconditional answers but would appreciate opinions. Please notice
I haven't mentioned methods-----just would like to have a number to work toward-----haven't
called BR-549 yet.

Thanks.

A. Weldy

 

[seymour fish]

I know we'd all like to truthfully brag about getting "zero" runout but what is honest practicality ?

In the quest for serious BR accuracy, how much runout can we tolerate before we call for help ?

I realize there are no firm and unconditional answers but would appreciate opinions. Please notice
I haven't mentioned methods-----just would like to have a number to work toward-----haven't
called BR-549 yet.

Thanks.

A. Weldy

Lucky, in my limited experience runout of up to .003 shoots the same as zero runout at 1000

 

[Lucky Shooter]

Thanks for your reply.

How about your equipment and methods to keep runout under .003" ?

A. Weldy

 

[nso123]

I stated seeing very low runout numbers when I introduced annealing and an expander mandrel to my reloading process. I used to get runout in the .003-.004 range, with some less, but now rarely get over .002.

 

[TAJ45]

Alan, our Bud did a test on chamber runout. He purposely started around .008 or so w a bbl of known accuracy, chambered, shot groups, then whacked off enough to set it up several thou less and repeated till he was at or under .003. It seems the last couple of thou made so very little difference.... Maybe ask him next time y'all visit and get it straight from the horse's mouth.

 

[Lucky Shooter]

Thanks again for all the replies.

I don't intend to be forever measuring and checking.

I'll do what I can to find a method that produces reasonable results
and then load 'em and shoot 'em.

I'll be listening to what folks here think and then do my best----hopeully
it can be simple.

 

[JohnKielly]

Depends what gun you're shooting.

If it's a sloppy chambered factory gun it's likely to be more of an issue than a custom job with a throat half a thou over bullet diameter.

 

[mikecr]

If it's a sloppy chambered factory gun it's likely to be more of an issue than a custom job with a throat half a thou over bullet diameter.

I disagree and believe reality is just opposite.
There are various attributes with runout that are not the same. Most often runout is seen as crooked ammo, the side affect of a lot of FL sizing(not custom). This where the numbers get up to 3thou and beyond as measured at necks. That ammo does still shoot well in sloppy chambers, a perpetuating contributor to crooked, but not so well in tighter chambers.

Then you have a lower tier of runout (<2thou) from those who custom size and/or partial neck size with little to no body sizing. This is straight ammo with neck thickness variance and/or seating alignment issues.
This will shoot well in tighter chambers, and those tighter chambers perpetuate low runout. They will shoot well in sloppy chambers to.

Then you go to fitted chambers plus custom sizing, producing TIR as measured off seated bullets, below 1thou. A fitted chamber holds clearances at or below 1thou total -anywhere. I have one and can tell you that ~3thou TIR ammo shoots like sh*t in such a chamber. I tested this one day. it's a step change.
But again, the runout produced here is perpetuated, and there is no way to 'accidentally' produce greater than 1thou TIR ammo pulled from such a chamber. You'd have to heavily FL size or something. I skewed necks for my testing.

This tells me that the affect of runout to results is not about mythical alignment, but about chambered tensions. So while your runout and chamber clearances allow chambering without tension, the ammo will work ok. It passes tests.
Ultimately, straight ammo doesn't hurt a thing.

 

[bloc]

Could someone please clarify?

If someone says his runout is .004, does this mean ± .002, or does it mean ± .004?

 

[Nature Boy]

Could someone please clarify?

If someone says his runout is .004, does this mean ± .002, or does it mean ± .004?

My understanding and if wrong please tell me because I check run out on every round

A Total Indicated run out of 0.004” would be 0.002” per side. The TIR is what we reference

 

[BoydAllen]

Generally when we speak of runout we mean the total swing of the needle as the round or case is rotated a full turn. In these discussions it would be better if we defined what was meant by good accuracy. For my tight necked PPC I accept anything under .002 measured on the bullet about .1 out from the case neck. Typically I get .0015 or less. A seating die cannot straighten a case neck, but it can seat with worse runout than a better one. The key is sizing. One piece dies that have the correct neck ID perfectly in line with the rest of the die are the best, better than bushing dies. I have one and the runout of sized cases runs about a third of of thousandth at the end of the neck. Sometime back I compared the runout of rounds using a Hornady seater, one with the short sliding sleeve, with a Wilson, for my PPC, using cases with the same runout. The Hornady seated round had twice the runout of the Wilson. I have seen good results from Redding Competition seaters, especially after a couple of changes, as well as Forster. A friend is doing something entirely original with his seating for one rifle, with better results than he had been getting. PM me if you want to know about that.

 

[LarryDScott]

I size unturned necks w/a Harrells bushing die,and use a Redding comp seater, and found this combination to be so consistent that I sold my RO gauge. Does this equate to me being a better shooter?? NOPE. LDS

 

[Lucky Shooter]

Bless you Larry-----ain't simple great.

The older I get, the more I love it.

A. Weldy

 

[T-shooter]

There are a lot of places to measure runout. Right or wrong, I like to measure 1/2 way out to the tip. Usually, depending on the brass, I can get 50-60% or more at .002" or under. Maybe another 25% at or under .003". The rest are used for fouling or warmup shots or broken down, annealed and redone. I've had to anneal new brass and resize to get decent results even after neck turning.

 

[Uncle Ed]

With a full length resized cartridge the case body and neck do not touch the chamber walls. Meaning the cartridge has "wiggle room" for the bullet to be self aligning in the throat. Below German Salazar explains the benefit of full length resizing.

To me this means full length resizing can reduce the effects of bullet runout because the case shoulder is the only part of the case touching the chamber walls.


"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."

The Rifleman's Journal
Germán A. Salazar


Below a cartridge with excessive neck runout and the bullet hitting the throat and causing bullet misalignment with the axis of the bore.

I have both runout gauges pictured below and the red Hornady gauge is holding the case as described by German Salazar. And this type gauge reads far less runout than cases that rotate on the case body.

Now the funny part, the bottom image below is like a snug fitting neck sized case with the case body having more effect on bullet alignment with the bore. And a fat larger diameter chamber gives the case more room to expand and warp when fired if it has unequal case wall thickness.

This gives more meaning to what the late Jim Hull of the Sierra ballistic test lab and competitive shooter said in a joking way about full length resizing. "The cartridge should fit the chamber like a rat turd in a violin case"

 

[mikecr]

The low reading gauge (neck bender) is lying to you about the straightness of your loaded ammo.
Believe me, straight ammo reads so on a v-block type gauge.

Also, you don't have to FL size to make straight ammo. And you don't need a sloppy chamber to shoot well.
But if you're making crooked ammo, likely due to excess sizing, then you'll have better results with a sloppy chamber, which leads back to excess sizing -completing the loop.
It's self perpetuating.

It is just as self perpetuating to manage lower and lower runout paths.

 

[Ccrider]

So @Uncle Ed and mikecr, are you saying that the runout measurement from the Hornady gauge is inaccurate?

 

[Sixgun]

Could someone please clarify?

If someone says his runout is .004, does this mean ± .002, or does it mean ± .004?

No...its .004. Roll your round on your indicator..when the dial stops....zero the dial...roll again.

 

[mikecr]

So @Uncle Ed and mikecr, are you saying that the runout measurement from the Hornady gauge is inaccurate?

It flat out lies to you. Reads nearly nothing of your actual runout.
Consider a jump rope solidified, pinned at both ends, and Rotisserie turning. If you wanted to measure it's arc you'd measure at the center of it's arc(greatest deviation). If you purposely wanted to miss the arc (lowest deviation), you'd measure all the way at one end (like the Hornady).

The Sinclair v-block would pin the center of this jump rope, turning from that point, and measuring full arc from an end. If you're making, or not making straight ammo, this shows it.

 

[Tim Singleton]

I try for less than .001 a lot of people I know think it makes a difference