Loaded ammo bullet runout???

[Boss Hoss]

Bottleneck cases headspacing on their shoulder align bullets in the front of the chamber equally perfect up front in all chambers. Doesn't matter how the fired cases are resized as long as there is at least .0005" clearance around the case.

Get rid of that expander, deprime cases before cleaning them then use a bushing 3 or 4 thousandths smaller than loaded round neck diameter.

Bullets don't need runout under 1% of bullet diameter.

If you say so---my dies (both) are made when the chamber is cut and the brass is perfectly prepared. Factory chambers and commercial dies are a crap shoot. There are tools that allow for correction of this problem. I don't have the link anymore but use the tool as modified with a more precise gauge.

Found it:

http://bulletin.accurateshooter.com/2010/10/hh-concentricity-gauge-bullet-straightener/

 

[Bart B]

Factory chambers and commercial dies are a crap shoot.

Commercial dies and SAAMI spec chambers (which is what commercial factory rifle barrels use) have been shooting well enough to win virtually all of the high power matches and set virtually all records as well as shooting test groups smaller than many current benchrest records since the early 1960's. And they don't prep their cases except for sorting by weight to 1% spread and turn necks to get less than 1/1000th spread in wall thickness.

Sierra Bullets uses commercial Redding full length sizing dies on their cases used to test their products for accuracy in SAAMI spec (or virtual copies thereof) chambers. I doubt anyone shoots their bullets more accurate than they do. Sierra doesn't do any case prep whatsoever. And they meter, not weigh, powder charges.

The only crap shoot's the way folks select and use the dies; not the way they themselves work. Especially with today's full length bushing dies.

And it's a myth that cases have to be a "perfect" fit to the chamber with minimum clearance all the way around the case to the chamber for best accuracy. Best proof of this is the M14 and M1 service rifles rebuilt to shoot 7.62 NATO mass produced ammo. With their extra moving parts having to go back into battery exactly the same for each shot, they won't be as accurate as a bolt gun. But they'll shoot a good lot of commercial match ammo under 2/3 MOA at 600 yards all day long; not too shabby at all for new cases, metered charges and bullet runout up to 3 or 4 thousandths. And mil spec chambers, too, which allow for a lot of room around a loaded round. That same ammo in a bolt gun will shoot 1/2 MOA at 600 or better and that's what the benchresters get these days as that's what their rifles shoot.

 

[Boss Hoss]

Sorry Bart you are wrong on so many levels I don't know where to start. Been to a lot of BR matches and even won a few and have never seen a factory rifle win EVER. Either at 100 or a 1K.

Did not know that you shot BR....

 

[rscott5028]

If you say so---my dies (both) are made when the chamber is cut and the brass is perfectly prepared. Factory chambers and commercial dies are a crap shoot. There are tools that allow for correction of this problem. I don't have the link anymore but use the tool as modified with a more precise gauge.

Found it:

H&H Concentricity Gauge and Bullet Straightener « Daily Bulletin

Boss Hoss,

I hope you're just throwing that straightener tool out there as an fyi.

For me, straightening is a waste of my time.

My perspective FWIW is that it's not so difficult to produce straight ammo. If it doesn't come out straight, then I probably did something wrong.

I prefer to simply sort/cull anything that doesn't meet my standards into the practice pile. Even then, I find that up to .005" TIR is still good for .5 MOA in at least some of my rifles. ...not BR quality. But, it's not like you suddenly go from .25 MOA to 3 MOA.

The best straightener is to fire the brass in a good chamber, figure out the problem, and reload.

-- richard

 

[Boss Hoss]

.5 MOA on any of my rifles and they go back for a new tube lol. The tool above does both operations if you so choose. Problem with firing and the sizing is that Sometimes the Chamber and the Die are not different dimensions or maybe not completely concentric. This is a problem that can get very complex--even gets into brass spring back.

This will be my last post on this thread---am reminded why my visits are infrequent..

 

[rscott5028]

.5 MOA on any of my rifles and they go back for a new tube lol. The tool above does both operations if you so choose. Problem with firing and the sizing is that Sometimes the Chamber and the Die are not different dimensions or maybe not completely concentric. This is a problem that can get very complex--even gets into brass spring back.

This will be my last post on this thread---am reminded why my visits are infrequent..

Well, I appreciate your responses nonetheless.

Thanks
Richard

 

[Trickymissfit]

I am using a RCBS Rockchuncker press w/ Redding comp seating micrometer dies (7 WSM and 6BR, loading Berger VLD's in both) and getting bad runout on the loaded ammo. I have already added VLD seater stems to both dies.

Brass on both has been neck turned and being resized with Redding neck bushing dies.


Any suggestions as to what part of my equipment could be to blame/need replacing??

well you've stated that you have the same issue with two different die sets, so the next thing to check is what a resized case looks like. They'll also show a similar issue; my guess that is. If so, the next thing to look at is the press (here we go again). My suggestion is to find somebody with a different press, and try the same setup on their press. I simply cannot imagine you having two bad die sets in a row, although Redding did build quite a few bad 6BR dies sets a few years back. If they are bad, then good luck talking with them because 98% have zero luck with them.

I shoot for a .0025" TIR window when loading ammunition (+/- .00125"). I don't always get that number but usually come very close if I don't. If your problem comes with just the seater and not the case body's runout, then you might have a bad seater. My guess is that the sizing dies are where the runout starts, and a seater can never correct this issue. If it is in the case, start with the shell holder(s). Look closely at the surface they set on for a burr or even something that will cause the shell holder to not seat solidly in the ram (I've seen this one many times). Now take a case that you know is good, and seat in the holder, but leave the retaining mechanism slightly loose. Install the sizer die with the jam nut slightly loose, and size the case. When the case is all the way in the die tighten everything up. See if the case is good. If not, it's time to try another press.

Presses with a single spindle type rams will torque a little bit during their upwards travel. (they have no guide rods to maintain alignment.) If your still seeing runout now, pull the link bars from the ram. See how much movement you have between the bore of the press and the ram. If you see .002", you can pretty much double that for minimum runout (TIR). This issue is quite common. If the bore is bad, the fix is a pain in the butt.
gary

 

[redgun]

UPDATE:

I took the expander off of the resizing die, then resized & loaded a few 7 WSM rounds..........

.002"-.004" average runout

It appears that the expander was bending the case necks.

 

[rscott5028]

Mark - Congrats! Glad you solved the mystery. It's soooo much better to load it straight than to straighten it after bending.

[...]
I shoot for a .0025" TIR window when loading ammunition (+/- .00125").
[...]

Gary - I just learned something new. I didn't realize you could have a negative TIR.

--Richard

 

[Joe King]

UPDATE:

I took the expander off of the resizing die, then resized & loaded a few 7 WSM rounds..........

.002"-.004" average runout

It appears that the expander was bending the case necks.

It might be worth your time to check out a Lee collet neck sizer, lots of folks seem to like em. I'm trying one out now, not that I ever had an issue with excessive runout, but every little bit helps.

 

[Broz]

UPDATE:

I took the expander off of the resizing die, then resized & loaded a few 7 WSM rounds..........

.002"-.004" average runout

It appears that the expander was bending the case necks.

OOOoooo, that guy in post #5 nailed it. He really knows his stuff....

Just kidding, glad yo got it under control.

Jeff

 

[Trickymissfit]

Mark - Congrats! Glad you solved the mystery. It's soooo much better to load it straight than to straighten it after bending.



Gary - I just learned something new. I didn't realize you could have a negative TIR.

--Richard

here's the deal on all this TIR crap shoot. I do not like to adjust an indicator once it's set, but some guys do. On my Interrapids I can move the dial without disturbing the location much. I rarely use one of the long travel dial indicators due to their excessive built in lag (most have 10% backlash). So I use wand type indicators 95% of the time. I don't like using one tenth indicators much even though I own many of them. Use a .0005" one or a .00025" one most of the time.

Back to the slop in the ram quotation I made (we call that lag by the way). Every ram will have clearence built into it, or you couldn't move it. The rule of the thumb is that if by chance you had .001" clearence in the ram (and guide rods if it comes with them); you'd be hard pressed to load anything less than .002" TIR. In machinery (and a press is a machine) you soon learn this. This is why I brought up the question of built in lag with the press. (looks like he's got about .002" maybe) Now we take all the pieces we are using to size and reload a certain round. I'd bet the farm that there is no perfectly machined piece in that pile of stuff; no matter who made it. You add the die an pick up another five tenths, and a tenth from the shell holder alone. Error in a die is not usually as critcal as the shell holder due to the way the triangle figures out. The longer the case the higher the multiplier is at the base. I personally don't trust any of them.

Measuring case runout is also a crap shoot when you set down and look at it. I use three different gauges. A NECO, and two home brew affairs. Each one works much differently than the others, and each one will show you errors that the others won't. The NECO uses a vee block affair, and I'm not in love with area contact for precision measurments. But it's still a very good unit. One of my others works off of pins, and it's pretty good at picking up the slightest banana. The other uses a series of balls that have minimum area contact. The only moving part is the indicator wand. (in OTW zero lag built into it) Still it will not do everything I want. I'm also a big proponet of the use of multiple indicators on a gauge. Makes it easier to spot runout as it builds up, plus easier to find the high spots and low spot. Still after awhile you end up whipping a dead horse due to other problems.

As for the O.P., I'm glad he got his back down to earth. He now needs to start tweeking a tenth or two out of his setup here and there. A burr here and a hicky there will make up another thousandth.
gary

 

[Joe King]

Gary I really do believe lots of folks would be mighty depressed with their equipment if they really understood just how limited the measuring equipment is that we have available to us at a reasonable/affordable cost. OTOH I think they would be pretty impressed with how well we can get our guns and ammo to perform in spite of it.

 

[Mikecr]

We make ammo as straight as we can,, below any affects of it,, and there are plenty of basic runout gauges accurate enough for it.

Where it gets tougher is with bullet measurements..