The true cost of non-concentric Ammo

Reloading equipment, methods, load data, powder and projectile information.

The true cost of non-concentric Ammo

Post by Stix » 26 Apr 2020, 8:08 pm

What are the effects of non-concentric ammo...?

Everything i see on the internet goes to showing the "how to's" of making concentric ammo...but i cant find any examples of hard, quantifyable data & examples of ammo that is identical in every way, except for concentricity, & how it prints on paper...

There are plenty of examples of neck tension for example, & that is possibly measured easier, but...
Can any of you guys throw any light on the subject, with any more authority than "it just is"...?

For example...for starters, what is an acceptable/or typical amount of error found from the average but keen hand loader pumping out handloads on the typical press...

Then also...if a heap of ammo that was 5 or 10 (? :unknown: ?) thou out of round (as measured at the bullet), was shot at 2-300 yds in direct comparison to ammo with a max of .5-1 thou runout, in say a 223, what sort of result difference could we expect...(for example-a random placed group opened up a full MOA... :unknown: ).

Anyone tested this...?...or have found something on the WWW showing actual results...?

Cheers
The man who knows everything, doesnt really know everything...he's just stopped learning...
Stix
Colonel
Colonel
 
Posts: 3675
South Australia

Re: The true cost of non-concentric Ammo

Post by Bill » 26 Apr 2020, 8:20 pm

its an interesting question Stix, do you think neck tension is more important than concentricity thou ?
When a guy is digging his own grave, you don’t fight him for the shovel.

Success leaves clues, Fools follow failure !

20 Hornet, 218 Bee, 222 Rem, 256 WM, 6mm ARC, 6.5 Grendel, 6.5x55 Scan, 270 Win, 357 Mag, 358 Win, 9.3x62, 500 A Square
User avatar
Bill
Warrant Officer C1
Warrant Officer C1
 
Posts: 1253
New South Wales

Re: The true cost of non-concentric Ammo

Post by Blr243 » 26 Apr 2020, 8:28 pm

Never put any thought into it other than like a sheep I follow the advice of others and hope they are right. I started neck turning my 243 cases because of brass flow and neck thickening. I wanted to be safe and not risk dangerous pressures from excess neck tension .... not once have I done it to improve concentricity but cool if it’s a bonus ..... I was surprised the first time I neck turned at how out of round my cases were ......the cutter would clean miss one side of the neck and take a heap of brass from the other side ......... I think it would be hard to test for accuracy of turned vs non turned necks because neck tension would probably be different and tons of people on this site say varying neck tension has a significant effect on group size
Blr243
Brigadier
Brigadier
 
Posts: 4479
Queensland

Re: The true cost of non-concentric Ammo

Post by marksman » 26 Apr 2020, 10:04 pm

David Tubb did this test and proved that non concentric ammo of less than 2 thou runout was good enough for a competition, over 2 thou but under 5 thou runout was good enough for hunting eg... 1 moa and over 5 thou runout was not good enough for hunting, concentricity is important
its in one of his sierra videos

there is a lot in this Stix but really it is just trying to do the same thing over and over the same way with the same thing
really its just precision

no different to building a house start square, keep square and it will be square

regarding neck tension, if your cases are all the same neck tension they should really perform very similar no matter what the neck tension is
differing tensions will give differing results, l do know you know this though Stix
“If you do not read the newspapers you are uninformed. If you do read the newspapers you are misinformed”. Mark Twain
User avatar
marksman
Colonel
Colonel
 
Posts: 3660
Victoria

Re: The true cost of non-concentric Ammo

Post by Sergeant Hartman » 26 Apr 2020, 11:44 pm

Are you hunting or benchrest.

Seriously keep it simple mate, have fun poofteenth of an inch will not matter to the deer or roo
Sergeant Hartman
Sergeant Major
Sergeant Major
 
Posts: 1722
Victoria

Re: The true cost of non-concentric Ammo

Post by straightshooter » 27 Apr 2020, 7:16 am

Stix wrote:.......or have found something on the WWW showing actual results...?


Much of what you find on the internet isn't worth the paper it's written on.
Googleperts generally don't have access to older benchrest oriented books or have read old precision shooting magazines where bullet run out and how to deal with it was often dealt with at length.
"Anything is possible if you don't know what you are talking about."
"There is no expedient to which a man will not resort to avoid the real labor of thinking." Sir Joshua Reynolds
straightshooter
Warrant Officer C1
Warrant Officer C1
 
Posts: 1263
New South Wales

Re: The true cost of non-concentric Ammo

Post by Noisydad » 27 Apr 2020, 1:09 pm

Interesting indeed! While not really comparing apples with apples, in BP shooting with big single shot rifles it’s fairly common to use zero (as in NONE) neck tension with bullets loose seated. My Sharps is loaded like this and has shot sub MOA at 600 yards twice. Wish I could do it again lol.
There's still a few of Wile. E Coyote's ideas that I haven't tried yet.
User avatar
Noisydad
Warrant Officer C1
Warrant Officer C1
 
Posts: 1383
Victoria

Re: The true cost of non-concentric Ammo

Post by marksman » 27 Apr 2020, 5:59 pm

that reminds me of an old benchrest trick l heard a long time ago about how they would ream the top half of the neck so there was a step inside the neck and very little holding the bullet for near to no neck tension in single loaded bench rifles for best presision, l have not tried it but it was a thing for a while l heard

here is an old thread you may want to revisit Stix viewtopic.php?f=3&t=9171
“If you do not read the newspapers you are uninformed. If you do read the newspapers you are misinformed”. Mark Twain
User avatar
marksman
Colonel
Colonel
 
Posts: 3660
Victoria

Re: The true cost of non-concentric Ammo

Post by SCJ429 » 28 Apr 2020, 7:44 am

The best way to demonstrate any loss of accuracy due to large amounts of run out is to make up some loads with unacceptable run out and compare the results with loads that have low amounts.

I think that run out is detrimental to accuracy, I cannot see how it could improve it. I do think that consistent neck tension is a major factor in producing quality loads but you also need to get all the little things right as well.
SCJ429
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 3208
New South Wales

Re: The true cost of non-concentric Ammo

Post by Madang185 » 28 Apr 2020, 9:08 am

The whole area around the case mouth , is in my opinion, a virtual minefield of conflicting issues. Change one and you alter the overall picture. Recent information from New Zealand shows the importance of annealing. projectile run-out is another. I do not know what is acceptable or not, but suggest that it may in fact be related to the overall accuracy of the rifle plus the quality of the ammunition used.

Possibly only bench rest rifles have the overall accuracy to measure any particular changes. We are still learing
Madang185
Private
Private
 
Posts: 72
Victoria

Re: The true cost of non-concentric Ammo

Post by TassieTiger » 28 Apr 2020, 3:15 pm

I personally just don’t have the free time to go the nth degree of measuring like some but I’ve found - as Others have advised - getting powder, primer and seating depth (basics) all consistent - is not enough to shoot consistently as well, as the rifle can actually do.
Tikka .260 (Z5 5x25/52)
Steyr Pro Varmint .223 - VX 3
CZ455 .22 & Norinco .22 (vtex 4-12, bush 3-9)
ATA 686 U/O 12g & Baikal S/S 12g.
Adler a110 reddot
Sauer 30-06 - VX 3
Howa 300 win mag. SHV 5-20/56
Marlin SBL 45/70
TassieTiger
Colonel
Colonel
 
Posts: 3704
Tasmania

Re: The true cost of non-concentric Ammo

Post by SCJ429 » 28 Apr 2020, 4:58 pm

Madang185 wrote:The whole area around the case mouth , is in my opinion, a virtual minefield of conflicting issues. Change one and you alter the overall picture. Recent information from New Zealand shows the importance of annealing. projectile run-out is another. I do not know what is acceptable or not, but suggest that it may in fact be related to the overall accuracy of the rifle plus the quality of the ammunition used.

Possibly only bench rest rifles have the overall accuracy to measure any particular changes. We are still learing


Information from New Zealand? From AMP?

https://www.ampannealing.com/articles/

The reason annealing is important would be because work hardened brass will give you inconsistent neck tension wouldn't it?

Wouldn't any rifle show an improvement from quality ammo? My Tikka hunting rifle will shoot 1/4 MOA with handloads but struggles to keep it under an inch with factory stuff.
SCJ429
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 3208
New South Wales


Back to top
 
Return to Reloading ammunition