How do you straighten runout?

[rscott5028]

I made copious notes and compared accuracy of low TIR (<.002") vs high TIR (>.005") vs straightened cartridges (>.005" straightened to <.002"). Nothing scientific.

I concluded it's essentially a waste of time to bend case necks for the reasons Mikecr and others explained.

My salvation was better brass, tools, and processes.

-- richard

 

[Bart B]

I've straightened bullet runout a very simple and easy way that doesn't change neck tension on the bullet. There are tools out there that do this; stay away from them. You'll first have to spin your ammo marking the high point of bullet runout just in front of the extractor groove on the body. Use one dot with a Sharpie for each thousandth the runout has; 4 dots for a .004" runout.

First, mic your loaded round neck diameter. For my 30 caliber cases, their neck diameter's about .338 inch.

Second, get a bullet puller that size. I've got an RCBS one with a collet for .338 bullets. Set it up in your press such that it'll just barely hold onto a loaded round neck with the case body about half an inch above the shell holder.

Third. put the loaded round up into the bullet puller then lightly tighten the collet with the dots facing forward towards you.

Fourth, push in (away) at the dots such to slightly bend the case neck to about straight.

Fiftn, spin the round again to see how much straighter the bullet is.

Repeat these steps 'till all your ammo's got very straight bullets.

Depending on how ductile the case necks are, different amounts of force will be needed. Most folks will quickly learn how much force is needed to reduce runout a couple thousandths.

Used to do this a lot with Lake City match ammo for service rifle matches, Improved accuracy quite a bit. 30 caliber bullets with up to .003" runout need not be corrected. The limit seems to be .001" for each ten calibers of bullet diameter; a 40 caliber cartridge can have up to .004" runout; 22 caliber ones up to .0022".

Using bushing dies without expander balls is the best way to get straight case necks. With these dies, you can seat bullets with a ball peen hammer and they'll be very straight. If the case neck's bent, no bullet seater will make 'em straight; inline or whatever. RCBS and Redding make good ones. Sierra Bullets uses Redding full bushing dies to full length resize their cases used to test bullets for accuracy. They get best accuracy full length sizing; always have since the 1950's.

 

[Bart B]

I've straightened bullet runout a very simple and easy way that doesn't change neck tension on the bullet. There are tools out there that do this; stay away from them. You'll first have to spin your ammo marking the high point of bullet runout just in front of the extractor groove on the body. Use one dot with a Sharpie for each thousandth the runout has; 4 dots for a .004" runout.

First, mic your loaded round neck diameter. For my 30 caliber cases, their neck diameter's about .338 inch.

Second, get a bullet puller that size. I've got an RCBS one with a collet for .338 bullets. Set it up in your press such that it'll just barely hold onto a loaded round neck with the case body about half an inch above the shell holder.

Third. put the loaded round up into the bullet puller then lightly tighten the collet with the dots facing forward towards you.

Fourth, push in (away) at the dots such to slightly bend the case neck to about straight.

Fiftn, spin the round again to see how much straighter the bullet is.

Repeat these steps 'till all your ammo's got very straight bullets.

Depending on how ductile the case necks are, different amounts of force will be needed. Most folks will quickly learn how much force is needed to reduce runout a couple thousandths.

Used to do this a lot with Lake City match ammo as well as reloads for matches, Improved accuracy quite a bit. 30 caliber bullets with up to .003" runout need not be corrected. The limit seems to be .001" for each ten calibers of bullet diameter; a 40 caliber cartridge can have up to .004" runout; 22 caliber ones up to .0022".

Using bushing dies without expander balls is the best way to get straight case necks. With these dies, you can seat bullets with a ball peen hammer and they'll be very straight. If the case neck's bent, no bullet seater will make 'em straight; inline or whatever. RCBS and Redding make good ones. Sierra Bullets uses Redding full bushing dies to full length resize their cases used to test bullets for accuracy. They get best accuracy full length sizing; always have since the 1950's.

Note that straightening case necks must not change the relative seating of the bullets in the case neck. Bending things that support the round at bullet tip and case with pressure on the neck will change the neck's grip on the bullet. Using a collet like I explained doesn't change anything except where the case neck points relative to the case body axis.

 

[BountyHunter]

Using bushing dies without expander balls is the best way to get straight case necks. With these dies, you can seat bullets with a ball peen hammer and they'll be very straight. If the case neck's bent, no bullet seater will make 'em straight; inline or whatever. RCBS and Redding make good ones. Sierra Bullets uses Redding full bushing dies to full length resize their cases used to test bullets for accuracy. They get best accuracy full length sizing; always have since the 1950's.

Bart hit it on the head.

Eliminate the expander ball, FL size with a bushing die that is fitted to the chamber. You can buy different decapping rods without expander balls.

If you need to expand the case necks to straighten out big dents etc, use an expanding mandrel then resize.

BH

 

[Bart B]

Eliminate the expander ball, FL size with a bushing die that is fitted to the chamber.
BH

By "fitted to the chamber," I agree. All that's needed for bottleneck cases (both rimless and belted), is the shoulder be set back 1 to 2 thousandths. And the fired case body needs to be sized down the same amount so there'll be no interference between the case's shoulder-body junction to the same place in the chamber. As all cases and chambers are a tiny bit out of round, ensuring these bottleneck cases seat fully against the chamber shoulder, they'll center perfectly aligning the case neck and bullet perfectly with the bore.

Sizing the fired case as such lets it "float" clear of the chamber walls except at its back end where the extractor always pushes it against the chamber wall at its back end. With belted cases, one should get a body sizing die that sizes the case body back to virtual new case diameter at the belt's front edge.

Strange as it may be, the most consistantly-accurate rimless and belted bottleneck case shooting rifles get best accuracy with either new cases or resized ones done this way. Neck-only resizing cases have never consistantly produced good accuracy, in my opinion. Note that benchrest competition accuracy (a whole lotta neck only sizing goin' on) ain't necessarily the most accurate centerfire group shooting that's been done.

 

[rscott5028]

I'm very surprised to hear about a Service Rifle guy exerting effort in this regard.

Other very successful competitors swear that they only weigh powder after ever 10-12 cases and that they load on progressive presses. Perhaps they too are more anal if not superstitious about their match ammo.

I still contend it's futile having tried it but, perhaps you found the perfect procedure.

At least we all seem to agree that it's best to prevent it in the first place.

 

[Gone Ballistic]

I've straightened bullet runout a very simple and easy way that doesn't change neck tension on the bullet. There are tools out there that do this; stay away from them. You'll first have to spin your ammo marking the high point of bullet runout just in front of the extractor groove on the body. Use one dot with a Sharpie for each thousandth the runout has; 4 dots for a .004" runout.

First, mic your loaded round neck diameter. For my 30 caliber cases, their neck diameter's about .338 inch.

Second, get a bullet puller that size. I've got an RCBS one with a collet for .338 bullets. Set it up in your press such that it'll just barely hold onto a loaded round neck with the case body about half an inch above the shell holder.

Third. put the loaded round up into the bullet puller then lightly tighten the collet with the dots facing forward towards you.

Fourth, push in (away) at the dots such to slightly bend the case neck to about straight.

Fiftn, spin the round again to see how much straighter the bullet is.

Repeat these steps 'till all your ammo's got very straight bullets.

Depending on how ductile the case necks are, different amounts of force will be needed. Most folks will quickly learn how much force is needed to reduce runout a couple thousandths.

Used to do this a lot with Lake City match ammo as well as reloads for matches, Improved accuracy quite a bit. 30 caliber bullets with up to .003" runout need not be corrected. The limit seems to be .001" for each ten calibers of bullet diameter; a 40 caliber cartridge can have up to .004" runout; 22 caliber ones up to .0022".

Using bushing dies without expander balls is the best way to get straight case necks. With these dies, you can seat bullets with a ball peen hammer and they'll be very straight. If the case neck's bent, no bullet seater will make 'em straight; inline or whatever. RCBS and Redding make good ones. Sierra Bullets uses Redding full bushing dies to full length resize their cases used to test bullets for accuracy. They get best accuracy full length sizing; always have since the 1950's.

Note that straightening case necks must not change the relative seating of the bullets in the case neck. Bending things that support the round at bullet tip and case with pressure on the neck will change the neck's grip on the bullet. Using a collet like I explained doesn't change anything except where the case neck points relative to the case body axis.

This is the best way I have heard yet. I just tried what you said on some 300RUM loads that were .004-.005 out. After playing with the first on for quite a while I got it down to .002. The second one I got down to .001. I tried 10 rounds and got everyone down to .002 or less. Fantastic Info. Anyone interested in a Hornady case concentricity guage real cheap?
Can't thank you enough for the info. You other guys, try this one, it works!

 

[rscott5028]

You can take the TIR back down from .005" or more to less than .001".

But, my opinion based on my testing is that it's still not going to be as good as those that came straight out of the seater die with <=.002". With good brass and tools, you shouldn't have any problems attaining that.

IMO - For practice ammo, it's not worth the effort. And, for match ammo, I won't accept it if it doesn't come out straight to begin with. But, then some of us weight every charge to the nearest .02g and some of us only weigh every 10th charge to the nearest .1g.

-- richard

 

[Bart B]

And, for match ammo, I won't accept it if it doesn't come out straight to begin with. But, then some of us weight every charge to the nearest .02g and some of us only weigh every 10th charge to the nearest .1g. -- richard

When a bunch of us developed the .308 Win. Palma ammo for the 1992 World Championships, our load was with new, virgin Winchester cases with a 3 grain spread, metered charges of IMR4895 with a 3/10ths grain spread, and Sierrra's then new 155-gr Palma bullet seated with runout up to .003 inch. All made on two Dillon 1050 progressive presses.

Tests with a 20 shot group of random ammo put 'em all inside 2.8 inches at 600 yards. The top 20 to 30 long range competitors from around the world with a variety of tifle barrel makes and specs all said it was sub half-MOA ammo at 600 yards in their rifles.

Darned few, if any, benchrest rifles do that well. And this was with an old 'pre '64 Win. action conventionally bedded in a wood stock.

Everything doesn't have to be "exact" for really good accuracy. There's more inaccurate shots with unbalanced bullets in a lot than what .002" of runout causes.

 

[rscott5028]

When a bunch of us developed the .308 Win. Palma ammo for the 1992 World Championships, our load was with new, virgin Winchester cases with a 3 grain spread, metered charges of IMR4895 with a 3/10ths grain spread, and Sierrra's then new 155-gr Palma bullet seated with runout up to .003 inch. All made on two Dillon 1050 progressive presses.

Tests with a 20 shot group of random ammo put 'em all inside 2.8 inches at 600 yards. The top 20 to 30 long range competitors from around the world with a variety of tifle barrel makes and specs all said it was sub half-MOA ammo at 600 yards in their rifles.

Darned few, if any, benchrest rifles do that well. And this was with an old 'pre '64 Win. action conventionally bedded in a wood stock.

Everything doesn't have to be "exact" for really good accuracy. There's more inaccurate shots with unbalanced bullets in a lot than what .002" of runout causes.

Bart,

That's phenomenal! And, congratulations. You guys service rifle and palma guys never cease to amaze me.

I hope you tossed out any with >.003" TIR and didn't bother trying to straighten them.

No doubt there are plenty of guys here that are a lot less meticulous than I am and still manage to shoot better than I do.

-- richard

 

[Bart B]

Bart, ...I hope you tossed out any with >.003" TIR and didn't bother trying to straighten them. -- richard

I didn't make the 1992 Palma team, cause I shot two crossfires (dropped 20 points in the tryout aggregate, way too many), but I did shoot that ammo the year before when it was first used in a big Palma competition. Had the high aggregate score over 5 days of matches at 600 through 1000 yards; first time that new bullet was used.

No, didn't toss any with runout over 3 thousandths. Wasn't able to spin the ammo 'cause it was issued to us on the line when the match started each day. I did buy a carton of 500 rounds afterwards then measured a bunch of them for runout.

I did shoot some of the bullets we got from Sierra for that ammo the next year. Here's what 20 of 'em did testing prone with the Paramount actioned rifle on sandbags at the stock's fore end and toe. Full length sized cases in a gelded die (no ball) with runout maxing about .002." Weaver T20 scope used for accuracy testing. Note shots 1 and 2 were the lowest in the group. Fired two sighters to get a zero then these 20 about 25 to 30 seconds apart.

 

[Mikecr]

Whomever among you that have 'bent necks' needing any straightening, have you considered how you CAUSED this?
Also keep in mind that all the notions about 'floating' FL sized chambered cartridges, should be qualified 'only with bullets jammed into lands, and with excess headspace'. Otherwise, there is no floating(not even theoretical), and the notions fall apart completely.
Competitive BR shooters FL size for a number of reasons, with little related to hunting cartridge accuracy.

It's pratically futile to argue concentric -vs- straight ammo benefits, as nobody has proven one performance betters the other. But certainly there are huge differences between them.
I produce ammo that I verify is straight, because with that it is also concentric. It represents a low sum of errors from my entire reloading system and strategy.
Basically, it's the best I can achieve.

I do not believe this can be achieved with heavily FL sized cases. Nor do I rationalize that it doesn't matter, regardless of what competitors do.
You can buy tools that provide the low readings you want. Bend necks to get readings you want.. But to ignore the causes of your runout seems pure lazy to me.
Seriously, why even bother to do it?
Do you really expect to improve with shortcuts?

 

[nheninge]

Amen mike, richard. No doubt the discussion will rage on though...

 

[Bart B]

Also keep in mind that all the notions about 'floating' FL sized chambered cartridges, should be qualified 'only with bullets jammed into lands, and with excess headspace'. Otherwise, there is no floating(not even theoretical), and the notions fall apart completely.

Are you implying that a full length sized rimless bottleneck won't "float" when loaded and be centered in the chamber such that the bullet's well centered in the bore?