Runout Question re Forster Ultra seating die

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sliceman

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I am new to reloading x 1 yr, currently working up loads for my 7-08 Cooper.
I have Berger 140 VLD's, WW brass, WLR primers.
I have a Sinclair digital runout gauge and have noted the following findings:

1 X fired brass, neck sized on a Lee Collet die
Neck diameter 0.310
Body runout(measured just below shoulder-body junction) 0.0005 or less
Neck runout(measured halfway down neck) 0.002 or less

2 X fired brass, after 2nd firing
Neck diameter 0.316
Body runout(measured as above) 0.0005 or less
Neck runout( measured as above) 0.002 or less

When I loaded the Bergers using my Forster Ultra Micrometer Seating die, the runout measured at the area of the ogive ranged from 0.002-0.008, with most being from 0.004-0.006. Accuracy has been so-so, 0.7-2.0MOA @ 200 yds, the bullet 0.090 off the lands(which they needed to be in order to fit in my magazine). A previous ladder test had indicated that there was a node for H4350 between 46-48 grains( although I used new brass for this).

Should this not be better using this premium seating die, and if so, do you have any reasons for it. The necks have not been turned- I was hoping to avoid buying the equipment as I reload only for hunting, but still want less than MOA accuracy from my Cooper 7-08 (they guarantee half-MOA)

Any ideas you have would be appreciated.

Sliceman
 
Its your sizing die or more likely the decapping rod.
0.002 at the neck equates to bigger issues at the bullet.

That said 0.006 run out will not create the poor accuracy you are experiencing.

I'd try another bullet to see if that is the problem.
 
Not sure if you have done any brass prep beyond cutting to length. The key point is if your brass starts straight the rest should follow. Suggest you mic case thickness at several points. I see your guage shows 2 thou runout at the neck. Very good, but could be made to 0 with neck turning. Did you check the seating plug to ensure the bullet is pressed on the ogive, not the point. Also, ensure every time that no burrs exist on the brass mouth when cleaning in a tumbler. Bullet seating should be smooth as silk. Hope these tips help.
 
I just got a .223Rem barrel chambered and spec'd it for a tight neck so I would have to neck turn. I FL sized and turned my brass (virgin Lapua) and fired, neck sized with a lee collet die and seated a bullet with the cheapo Lee seater die and I have less than .0010" bullet runout. I have a dial indicator that reads in .0005" graduations and it hardly moves. I was absolutely amazed at how straight it was and will always neck turn everything I have from now on.

If your neck is of varying thickness, especially with lower quality brass, you will be lucky to get down to .003-.004" runout.

That said, I honestly don't think runout is causing your accuracy problems. You should try a different bullet and see what happens, if not, I would be calling Cooper about that 1/2MOA guarantee.
 
As mentioned, check to make sure seater stem is not seating off the point of the bullet and try a BT bullet rather than a VLD if you are loading to mag length. I would test some single loaded rounds at .015 into the lands with those Berger's.

The Sierra 142's worked well for me in a 6.5-08 at 2950fps

Also, if you have another shell holder, give it a try. I had a holder, that when used, caused unreasonable runout. Tried another holder and the runout came down to where it should be.
 
Forster offers a special bullet seater for VLD type bullets (i.e., Bergers).

Also, if you go to the Berger site, their is a .PDF article giving advice on how to play with seating depth. However, If I were to guess, your problems would be solved with a proper bullet seater - .005" of neck runout is generally considered the upper limit for accurate hunting ammo. However, this recommendation applies to measurements at 1/8" to 1/10" in front of the case mouth. I don't know what the recommendation would be if measured at the ogive (i.e., where your measurements are being made).
 
Some points to consider:

1. Not sure if I quite follow your neck measurements. Are you saying 0.316" unsized, and 0.310" after sizing? If so that is a bit high for a semi-custom gun. Lee collet dies are very good in sizing without causing runout, but the more you size down, the more likely you are to cause runout. Some use a bushing die like the Forster Bushing/Bump die, and size down in two stages using two different bushings. Neck turning will make the issue worse as you will have to size down more.

2. You may want to try Lapua brass for a more uniform neck thickness.

3. One trick used by some is to seat the bullet in two or more steps, while rotating the case in the shell holder for each step.

4. Forster claim their Ultra Seater will seat the VLD bullets on the cone, but as another poster suggested it would be good to check that the seating cone contacts before the tip. Some just drill the center deeper.

5. Another trick is to just size 2/3 of the neck instead of the whole neck. This leaves the unsized 1/3 to center the brass in the chamber.

6. I would try some other bullets. An old study military study suggested 90% of accuracy is determined by the bullet, and 10% by the primer, powder, and case.

7. Did Cooper supply a test target with the gun. What ammo did they use? If not, why not call them and ask them for the best components to use. The gun has likely been chambered for a specific case and bullet.
 
I think RonAKA is spot on and so is the Military, you may not have enough twist to shoot the 140 vld bullets and burgers tend to like a jam and your at a heavy jump due to magazine length, I would try another bullet, mine loves the 140 Nosler Accubonds with Varget. RonAKA was involved in helping me with a runout problem once and .006 is to much to size all at once, use a bushing die and size in .002 increments for best results in low runout.
Wayne.
 
Thank you all for the comments and suggestions

Xfan, the runout of the neck sized and fired cases are the same, all less than 0.002, most 0.0015or less. How can the runout of fired cases(theoretically formed in a perfectly concentric chamber) be any better? What is considered a normal neck runout in fired cases(not resized)?

Elkhuntr, I have checked the seating plug, there is at least 0.3" clearance beyond the tip of the bullet.
I do not have any tools yet for measuring neck thickness.
Cases have been prepped, cut 0.005 less than max, deburred and champfered,flash holes deburred and primer pockets uniformed.

RonAKA, yes the necks measure 0.316 fired and 0.310 neck sized. I did not measure the diameter after loading, but is 0.310-0.311 in some cheapo Federal ammo I use for fouling shots.
I have thought about sizing down some Lapua .308 cases, but understand that I would need to neck turn them(and haven't got that equipment yet).
I do the rotating trick as I seat the bullets.
The test target for my Cooper measured 0.060 (shot at only 42 yds, though).They used 130 gr HPBT(brand unspecified) and 4064 powder.

Bozo699, the twist in my rifle is 1 in 10", which should stabilize up to 160 gr bullets. Berger recommends 1 in 11" or faster for their 140's, and 1 in 10" or faster for their 168's.

So to summarize my questions:
Am I measuring the runout in the right place, ie ogive, or should I be measuring on the bullet just beyond the neck?
Could this be due to insufficient neck tension, as the sized necks measure 0.310, and the necks of loaded ammo(albeit in a different brand of case) are only 0.310-0.311 ?

Sliceman
 
XFan may respond differently, but neck runout in a fired, unsized case should be .001" or less - any more may indicate a problem with the chamber (John Barsness, "Advanced Handloading: Beyond the basics" DVD).
Unless someone can provide you with any parameters for judging the acceptability of neck runout when measured at the ogive, I would stick to 1/8" to 1/10" in front of the case mouth - John Barsness suggests neck runout no-greater than .0015" for Hunting rounds, .001" for varmint rounds. I think RCBS recommends no more than .002" with its casemaster tool. However, measuring at the ogive seems to make the most sense - this is where the bullet will contact first, after all.
The problem seems to be happening at the bullet seating step - based on your neck runout measurements, I would be expecting no more that .005" of bullet runout. I would contact Forster and ask for info about the VLD seater stem (an option for Forster bench rest seater dies. I don't neck thickness would be the issue - unlike other neck sizing dies, the LCD pushes any neck thickness variation to the outside of the neck - your neck runout measurements are pretty good (where this variation would be detected).
 
sliceman said:
RonAKA, yes the necks measure 0.316 fired and 0.310 neck sized. I did not measure the diameter after loading, but is 0.310-0.311 in some cheapo Federal ammo I use for fouling shots.

I have thought about sizing down some Lapua .308 cases, but understand that I would need to neck turn them(and haven't got that equipment yet).
I do the rotating trick as I seat the bullets.

Could this be due to insufficient neck tension, as the sized necks measure 0.310, and the necks of loaded ammo(albeit in a different brand of case) are only 0.310-0.311 ?
Click to expand...

You will gain a little thickness in the brass by sizing down Lapua .308 but I suspect only a thou or so at most. Your chamber looks like it is 0.317 and with a 0.311 loaded neck that is 0.006" clearance. That is probably double the ideal 0.003", so you can afford to have the brass go a little thicker. You should not have to neck turn them.

On seating tension you will have to measure the same brass loaded. I would suggest 0.001" increase from sized to bullet loaded is the minimum and possibly ideal. Some use more though. Although the Lee collet is good, you have no real control of the neck size other than by reducing the mandrel diameter. I understand Lee will do that as a custom service. The tension being less than 0.001" could cause runout.

I have to admit I don't worry that much about runout as I jam the bullet into the lands about 0.010". I also leave the rear 1/3 of the case neck unsized so with 0.001" clearance. The way I see it, if the cartridge had runout before I load it, it is probably gone by the time it is chambered. But, having no runout before chambering can't hurt either.
 
Ron AKA said:
You will gain a little thickness in the brass by sizing down Lapua .308 but I suspect only a thou or so at most. Your chamber looks like it is 0.317 and with a 0.311 loaded neck that is 0.006" clearance. That is probably double the ideal 0.003", so you can afford to have the brass go a little thicker. You should not have to neck turn them.

On seating tension you will have to measure the same brass loaded. I would suggest 0.001" increase from sized to bullet loaded is the minimum and possibly ideal. Some use more though. Although the Lee collet is good, you have no real control of the neck size other than by reducing the mandrel diameter. I understand Lee will do that as a custom service. The tension being less than 0.001" could cause runout.

I have to admit I don't worry that much about runout as I jam the bullet into the lands about 0.010". I also leave the rear 1/3 of the case neck unsized so with 0.001" clearance. The way I see it, if the cartridge had runout before I load it, it is probably gone by the time it is chambered. But, having no runout before chambering can't hurt either.
Click to expand...

Amen! :p

I would think 0.002 run out in virgin once fired brass would indicate something wrong with brass or chamber?
Maybe I am spoiled by Lapua and custom barrel/chambers?

I must admit I missed the collet deal the first time around.
That said I would consider trying a regular sizer then come back to the collet deally later, but then again I really don't know much about those things.


Seems to me the rifle should shoot as is despite the run out.
I would try a conventional 120-140gr bullet such as what the test target was fired with. You can always go back to the Bergers later.
As was suggested the Berger may not like the twist or bullet jump in your rifle.

Good luck and keep us informed!
 
Thanks again for the suggestions gents.
I do have another accurate load using 140 gr SGK's and IMR 4895, seated 0.010 off the lands, but interestingly, results are better from new brass(neck sized on the collet die) than fired brass sized the same way.
My hope was to get a bit of increased range from the superior BC of the Berger bullet.

Sliceman
 
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