Concentricity variations with bullets/seating

deeangeo

Well-Known Member
It doesn't come as a surprise, but measuring F/L sized brand new Norma MSch 6.5x54 brass, concentricity between neck/body is max. .0005"/ 1/2 thou.
Bullet seating, using a Redding seating die with the correct 'dome' insert for seating a Hornady #2640 160gn RN bullet, produces even taking the very best care in technique when seating,
concentricity variations of - greatest majority within .0015" - .002" run out & some (5%) @ .003" run out, but 5% greater than .004" run out.

I have no idea why there are these variations, but guess it's either the bullet that's the problem, or harder to determine, but something I did while seating the bullet.
Odd!
 
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You maybe used a die that didn't centralize the bullet with the case along the axis. Did you insert the case deep enough into the die before adjusting the insert to give the required COAL?
Or -- Are you getting too much resistance to inserting the bullet into the neck? - You can have too much neck tension.
You can make bullet insertion less problematic by using a case neck expanding die - I use a Lee Expander - K3 when loading flat bottomed bullets with sharp corners on the base. Just a slight tweak is all that is needed. I then use the Lee Factory Crimp die to nip it back in place & get the neck tension.

Ian
 
I don't fully understand how you're measuring this, but might it be caused by the sides of the bullet being significantly tapered. Being an unashamed and grateful copycat, I am using the same materials...although am not yet concerned about concentricity beyond what i can see by eye.
I did a few rounds with new Norma brass and didn't bother FL sizing it because it seemed ok as supplied. All I did was use a bullet turned the wrong way round to even out any visible squishing of the case mouth and ensure the internal diameter was consistent. If the cases are still good enough to make you happy after sizing I can suggest the following:
Getting back to the point. The Hornady bullets were only .264 at the base and tapered an amount that would certainly allow the loaded bullet to be out of whack by .004 if the die had an internal diameter of .264. Might it be worth trying a paper patch or something ...see primitive diagram...20161210_131803.jpg

The figures on the diagram are approximate from memory, but I hope you get the idea.
 
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I haven't found my Lee expander die to be as great a success as the use of a vld chamfer tool & yes, I also use a Lee FC die to even out neck tension.

The Redding dies I use are generally fine, with the seating die especially suited to the RN bullet this cartridge utilises. Also, no, I don't feel any great resistance when the bullet is inserted to case neck. In fact the feel of bullet entering case neck is really rather smooth.
Whether or not useful, (there are arguments for & against) I also rotate the case/bullet when seating. I do so on the basis it can't do any harm and may be helpful.

Still however, these slight variations occur & although not a huge issue, just a tad frustrating they occur at all.
So, just wondering if I'm missing something.....other than getting a custom seating die made, which, for this ninety odd year old rifle, is probably carrying matters rather far.
 
Apthorpe I always F/L size new brass. Just something I've done from the start thirty odd years ago.
If you're using an inverted bullet to even out neck dings, your neck tensions will not be as they should be had you used a die with correct expander rod.
The die squeezes in the case neck and the expander rod re-opens the neck to correct internal dimension to grip the bullet properly. The bullet is a thou or so greater dia. than neck ID so your neck tension on those cases you treated to the inverted bullet will be a 'looser' fit.

I use a Sinclair concentricity guage to check run out. It's a simple enough tool to use & gives helpful, if sometimes frustrating information. However, in this instance, the case neck/body run out is not the problem. The bullet may be the problem, but I cannot determine if my seating technique or the actual bullet is the problem.
 
George have you tried pushing the bullets straight? I have often thought that the Hornady gauge/straightener is a good idea. ( CONCENTRICITY TOOL
SKU: 050076) Maybe one of these days I'll make something similar.
In the meantime my reloads shoot better than me (wonky or not so) it isn't a big issue.

Ian
 
George have you tried pushing the bullets straight? I have often thought that the Hornady gauge/straightener is a good idea. ( CONCENTRICITY TOOL
SKU: 050076)Maybe one of these days I'll make something similar.
In the meantime my reloads shoot better than me (wonky or not so) it isn't a big issue.
Ian

No Ian I haven't tried that as my guage doesn't have that facility. I suppose using a guage that does this can help, but I guess a re-crimp would be necessary to reset the neck tension, Yes/No??
 
I just had another thought. Does the profiled die bullet pushing insert have full contact on the bullet nose? It would centralize better if it has anular contact rather than by pushing with a ball joint type of contact.

Ian
 
I just had another thought. Does the profiled die bullet pushing insert have full contact on the bullet nose? It would centralize better if it has anular contact rather than by pushing with a ball joint type of contact.Ian

The bullet nose is more of a ball joint fit to the seating cup with this die, but I am assured by Redding that it's the correct fit. ??? !
Very likely this could be a 'centralising' issue though & one I try to address by wiggling the case/bullet to centralise in the neck chamfer while the ram is being raised. Well, I hope so anyway!
 
Try the same combo in another make of die.borrowed of course.i,m spitballing being a noob.

I have other dies for this cartridge AN DU RU.....however, the seating cup on these is for 'pointy' bullets like an SST rather than round nose. So not a suitable alternative.
Cheers.
 
Does it make any difference to the average 6.5 MS stalking rifle? It's not a widely seen bench rest competition combination after all! Years back when I got a concentricity gauge, I measured everything I loaded - bad news for your peace of mind and faith in equipment and ammunition.

In particular, I made the mistake of measuring runouts on 50 .303 loaded with the 174gn Sierra MK in widely available but not exactly match grade Greek HXP milspec cases. Runouts ranged from zero (one cartridge) to ~50 thou' with an average likely half way between those values. Panic! Should I tear them all down and start again? Investigate the issues? Yada, Yada! Then I stopped and thought for a minute. ERA P'14 rifle ........ well used, three quarters of a century old, military grade, mass manufactured to wartime standards, shot at large targets at modest ranges ......... forget it and just shoot the stuff. And it shot as it had always done which was actually very well by Historic Service Rifle standards and probably coincidentally I went out and shot my best 300 yards SR score ever with that rifle the following weekend.
 
Does it make any difference to the average 6.5 MS stalking rifle? It's not a widely seen bench rest competition combination after all! Years back when I got a concentricity gauge, I measured everything I loaded - bad news for your peace of mind and faith in equipment and ammunition.

In particular, I made the mistake of measuring runouts on 50 .303 loaded with the 174gn Sierra MK in widely available but not exactly match grade Greek HXP milspec cases. Runouts ranged from zero (one cartridge) to ~50 thou' with an average likely half way between those values. Panic! Should I tear them all down and start again? Investigate the issues? Yada, Yada! Then I stopped and thought for a minute. ERA P'14 rifle ........ well used, three quarters of a century old, military grade, mass manufactured to wartime standards, shot at large targets at modest ranges ......... forget it and just shoot the stuff. And it shot as it had always done which was actually very well by Historic Service Rifle standards and probably coincidentally I went out and shot my best 300 yards SR score ever with that rifle the following weekend.

Who knows Laurie! But I have the time & inclination to try to do better in achieving more & closer consistency of ammunition I make. Just looking for some ad hoc pointers to check out.
 
...greatest majority within .0015" - .002" run out & some (5%) @ .003" run out, but 5% greater than .004" run out.

Don't sweat over a run out like that. It'll shoot better than most can shoot unless off a bench on a still day. I'd be concerned about a 10 thou run out but, as Laurie said, it's not noticeable in most rifles.

Yes, one could go neck turning and fancy gear but that way madness lies IMO.

Have you tried the (really) old trick of half seating, backing out and rotating the round in the shellholder but half a turn?
It did make a difference with some of my loads.
 
Don't sweat over a run out like that. It'll shoot better than most can shoot unless off a bench on a still day. I'd be concerned about a 10 thou run out but, as Laurie said, it's not noticeable in most rifles.

Yes, one could go neck turning and fancy gear but that way madness lies IMO.

Have you tried the (really) old trick of half seating, backing out and rotating the round in the shellholder but half a turn?
It did make a difference with some of my loads.

Barkingsnake, It wont be noticeable at all when the bullet JUMPS into the rifling :D

Seriously try this deeangeo. Make a bullet with no primer and no powder, a blank. Seat the bullet head out far enough so that it will make contact with the lands. Fiddle with it till you get no run-out (completely concentric) Load it into your rifle then eject it,it should have some land impressions on it, and check your concentricity again.
Now repeat everything with a blank bullet that has a .004" run out and tell us what you find..
 
George have you tried pushing the bullets straight? I have often thought that the Hornady gauge/straightener is a good idea. ( CONCENTRICITY TOOL
SKU: 050076)Maybe one of these days I'll make something similar.
In the meantime my reloads shoot better than me (wonky or not so) it isn't a big issue.

Ian
No. These tools are worthless. I have one hanging on my shop wall. Any SD member willing to come by my house can have it.

To a greater issue.
Deeangelo:Your run out is fine. If you bought one of the afore mentioned tools, Hornady would tell you such in the accompanying literature. .003" is OK and frankly, we are not talking a precision match rifle here, right? If you want to minimize runout, try flaring the bullet mouth before seating the bullet. If you want to eliminate this dilemma entirely....
Stop Measuring Run out. It's just not that important for 99% of all shooting we do.~Muir
 
Apthorpe I always F/L size new brass. Just something I've done from the start thirty odd years ago.
If you're using an inverted bullet to even out neck dings, your neck tensions will not be as they should be had you used a die with correct expander rod.
The die squeezes in the case neck and the expander rod re-opens the neck to correct internal dimension to grip the bullet properly. The bullet is a thou or so greater dia. than neck ID so your neck tension on those cases you treated to the inverted bullet will be a 'looser' fit.
.
I did that because I unwittingly had broken the expander rod on a berdan case and the replacement hadn't arrived. However, I didn't get a neck tension problem because the inverted end of the bullet is significantly narrower in diameter than the base - so by sticking an inverted bullet almost up to the cannelure into the case mouth, I got an ID which was at least a thousandth or two less than the bullet diameter.
This is rather my point.....my hypothesis is that the bullet diameter tapers so much along the portion that appears to be parallel (from 264 to something like 254) that it could be seated out of alignment in a perfect case and a well adjusted die, if one accepts that the seating cone might not be sufficient to align the bullet perfectly. If you measure a bullet for diameter at base, at cannelure and before the start of the ogive, you will see what I mean. Unless I got an odd box of #2640s....
 
Hee Hee Muir. I was half expecting that from you. :D I remember you have said similar things previously I recall.
Possibly the greatest value of these type things may be psychological.

Ian
 
Hee Hee Muir. I was half expecting that from you. :D I remember you have said similar things previously I recall.
Possibly the greatest value of these type things may be psychological.

Ian

Ian, Your gauge reminds me of the most useless present I ever received. A suction pump contraption to replace the cork in a wine bottle. :D
 
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