Curiosity and possibly a dumb question, but....

Calibres, cartridges, ballistics tables and ammunition information.

Re: Curiosity and possibly a dumb question, but....

Post by SCJ429 » 08 Dec 2018, 9:35 pm

If you want to check how much neck tension influences consistant pressure you can just set your sizing die so that it sizes less than a tenth of the neck, just enough to hold the projectile. Then shoot a group across your chrono and see if your SD comes down.
SCJ429
Second Lieutenant
Second Lieutenant
 
Posts: 966
New South Wales

Re: Curiosity and possibly a dumb question, but....

Post by brett1868 » 08 Dec 2018, 10:15 pm

Accurate at long range should by all means translate to accurate at shorter ranges, accurate at short ranges doesn't always make it accurate at distance. As distance increases the variations in velocity will compound into larger variations of impact height. If enough work is done to eliminate the multitude of variables in rifle / cartridge then single digit ES & SD's should be possible but it becomes a game of diminishing returns. Here's a thought, is the 6.5mm which is deemed one of the more accurate calibers because of size or because, due to popularity there's a better choice of projectiles? If the beard grooming twat-knot bunch were suddenly driven to moisture by the 375 H&H would we see a bigger variety of high BC target projectiles?

I have managed to achieve the holy grail of low numbers in a large cartridge (2nd Row) and many smaller ones...This is one of my go to loads for 1000yd competition :) Data was captured from a 5 shot string using a Lab Radar and I've managed to repeat it more then once. Even with a 10 shot string I was still in single digits for ES & SD
Loads.JPG
Loads.JPG (53.27 KiB) Viewed 162 times
How's my posting?
Complaints, Concerns - 13 11 14
User avatar
brett1868
Lieutenant General
Lieutenant General
 
Posts: 3380
New South Wales

Re: Curiosity and possibly a dumb question, but....

Post by SCJ429 » 09 Dec 2018, 9:52 am

The amount of bullet runout on a 458 Woodleigh projectile is more than for a 6mm Berger. Not many guys are shooting match grade projectiles out of their 450 Rigby in any case. The extra runout negatively effects the neck tension and the way the bullet is presented to the lands when being fired. This and a host of other factors have made low SD number elusive for me. As you said, if everyone shot the 375 we would get better brass and projectiles, lots of research and I am sure 375 true potential would be realised, this has happened to a small extent with the 338 Lapua due to its popularity.

I was also surprised that after only 30 shots with a bench rifle, my SD increased. Also after only a couple of shots after being cleaned the barrel was ready to produce low numbers. I had thought that it needed 10 shots to settle down. I now understand how some guys could clean their rifles in the middle of a match and get them back shooting after a couple of sighters.
SCJ429
Second Lieutenant
Second Lieutenant
 
Posts: 966
New South Wales

Re: Curiosity and possibly a dumb question, but....

Post by TassieTiger » 14 Dec 2018, 5:45 pm

brett1868 wrote:Accurate at long range should by all means translate to accurate at shorter ranges, accurate at short ranges doesn't always make it accurate at distance. As distance increases the variations in velocity will compound into larger variations of impact height. If enough work is done to eliminate the multitude of variables in rifle / cartridge then single digit ES & SD's should be possible but it becomes a game of diminishing returns. Here's a thought, is the 6.5mm which is deemed one of the more accurate calibers because of size or because, due to popularity there's a better choice of projectiles? If the beard grooming twat-knot bunch were suddenly driven to moisture by the 375 H&H would we see a bigger variety of high BC target projectiles?

I have managed to achieve the holy grail of low numbers in a large cartridge (2nd Row) and many smaller ones...This is one of my go to loads for 1000yd competition :) Data was captured from a 5 shot string using a Lab Radar and I've managed to repeat it more then once. Even with a 10 shot string I was still in single digits for ES & SD
Loads.JPG


This is approximately 27.5 levels above where I am lol.
I had to google the interactions and calculations around ES and SD...

I can very much understand the quest for perfection but omg reduvibg variables to the level needed to get those numbers borders on insanity lol
Tikka T3 .260 (custom)
Steyr Pro Varmint .223
CZ455 .22 & Norinco .22
ATA 686 U/O 12g & Baikal S/S 12g
Steyr Pro Hunt 30-06 (Dud!!!)
Sauer 100 30-06
TassieTiger
Second Lieutenant
Second Lieutenant
 
Posts: 811
Tasmania

Previous

Back to top
 
Return to Calibres, cartridges and ballistics