6PPC-USA, Higth Speed/Accuracy

Boyd Allen said:
As long as the base of the bullet stays above the doughnut, IMO there is no problem.
Click to expand...

Thank you for this conclusion !

But I sorry, I don't understand "IMO" (I don't speak very well English, it's not always easy for me ...)

A+
Laurent.
 
Boyd Allen said:
Since you have an interest in, and have achieved some good results using an expander ball, perhaps you might be interested to know that Whidden sells expanders of different sizes that fit Redding dies as well as their own.
http://www.whiddengunworks.com/product/expander-ball-kits-and-sets/
I don't know if you really need the kit, but you might be able to talk them into selling you a couple of specific sizes, or you could buy a couple that are oversized and polish them down to whatever size you want. You could also experiment with more neck tension by polishing down a Redding expander and using it with a smaller bushing.
Click to expand...

Hello Boyd Allen! (I write my last message when you post this...)

I knew that John Whidden modular this neck tension whit a expender ball (to improve concentricity):), and it's this information I decided to test this method in 6 PPC!
But I don't know he sell this very interesting kit of several size of Expender ball!

Thank you very much for this information!!!

A+
Laurent.
 
In an ideal world you want reloads that are as straight as possible. In reality there are a lot of things you can do wrong that will kill accuracy, even if the bullet to case alignment is dead on. I have told this story here before, in fact I tell it every 2 or 3 years. Back in the late 80's I went through a phase of rolling all my loads on a v block and measuring the runout at the tip with a dial indicator. I sorted them in 1 , 2, 3, or more thousandths runout. The more than .003" loads were always used as sighters. Frankly the only thing I really ever learned was that all the shots I fired at the sighter went exactly where I aimed. Somehow even the loads with little or no runout were capable of either shooting Nines or ruining a group. I sold the v block and dial indicator a couple years ago after not using them for 20+ years.

I reiterate there is a whole boatload of things that can kill accuracy even if your load is perfectly straight. Not saying this test is futile , just saying I never found it to be all it was cracked up to be.
Dick
 
Dick Grosbier said:
In an ideal world you want reloads that are as straight as possible. In reality there are a lot of things you can do wrong that will kill accuracy, even if the bullet to case alignment is dead on. I have told this story here before, in fact I tell it every 2 or 3 years. Back in the late 80's I went through a phase of rolling all my loads on a v block and measuring the runout at the tip with a dial indicator. I sorted them in 1 , 2, 3, or more thousandths runout. The more than .003" loads were always used as sighters. Frankly the only thing I really ever learned was that all the shots I fired at the sighter went exactly where I aimed. Somehow even the loads with little or no runout were capable of either shooting Nines or ruining a group. I sold the v block and dial indicator a couple years ago after not using them for 20+ years.

I reiterate there is a whole boatload of things that can kill accuracy even if your load is perfectly straight. Not saying this test is futile , just saying I never found it to be all it was cracked up to be.
Dick
Click to expand...


Thanks for your report Dick, it is very interesting and joined that of Boyld when he said :
"The whole thing made me smile because I had previously put so much effort into producing straight ammunition"

I am convinced that "the better isn't to harm" and even if it remains a single psychological advantage.

I just choose the resizing method that will give me the straight reloads. Because I'm not a great shooter and it is more easy for me to control the runout to choose the right method.

Respecfully.

A+
Laurent.
 
Amiens.jpg

Enjoyed my trip this summer to Amiens. The cathedral is so impressive.
 
Berger Twist Rate Calculator for FB Bullets.

BERGEON said:
I read this morning this article :

http://bulletin.accurateshooter.com/2015/03/how-ballistic-coefficent-varies-with-twist-rate-stabilization/

I have doing just good tests with my BERGER 65 gr BT in my barrel 1:14'' and I want to look the result of this bullet in the Berger online calculator :

65_gr_10.jpg


I don't understand I have a good accuracy with my gun and this bullet (100 m)!
dscn6813.jpg


And the calculators tell me : The bullet is unstable.Expect bad accuracy, tumbling bullets, and keyholes in targets !!!

The more surprised is the "Minimum Twist stability recommended " is 1:11'' then this bullet is recommended to Berger "For 1 in 13" Twist or Faster"!!!

I don't understand more...

I will doing my future test at 300 m whit this 65 gr BT... I'm afraid to look some tumbling bullet in my target Now!

A+
Laurent.
Click to expand...

The Berger Twist Rate Calculator warning states:

» CLICK HERE FOR AN IMPORTANT NOTE ABOUT FLAT BASE SG CALCULATIONS

The Miller stability formula is most accurate for boat tail bullets, and typically underestimates stability for flat based bullets. In other words, if this stability calculator indicates low stability for your flat based bullet and barrel twist, it’s because the formula is not accurate for flat based bullets.
 
Boyd Allen said:
I like what you have done with the expander. It is unusual in benchrest to do that. So often shooters assume what the effect will be, instead of testing.
Click to expand...


BERGEON said:
I just choose the resizing method that will give me the straight reloads. Because I'm not a great shooter and it is more easy for me to control the runout to choose the right method.
Click to expand...

Yesterday in (goods conditions) I testing my resizing method with Busing+Expender ball and I think the results are good for me :

28_8_g10.jpg
28.8 gr N133, .002 75'' Neck Tension, Berger 68 gr FB Moly, LAPUA Brass, V0 =3352 Fps (My BORDER prefer always the high speed!!!:) )

0.176'' for a beginner with my Savage Action+Trigger Rifle Basix SAV-2

A+
Laurent.
 
Relation between Neck Clearance and accuracy...

BERGEON said:
I use two cases in my chamber (Reamer JGS N° 1261 6MM PPC SAKO; Neck .270'' )

-With NORMA case ( Factory to use "No Turn Neck!") The loaded round mics 0.264 17" at the neck! The clearance is so bigger ! .005 82 ''

-With LAPUA .220 Russian, with my Neck .270'' I turn the LAPUA Neck to have the loaded mics .267 32'' and with those LAPUA cases the clearance is .002 67''
Click to expand...

Now I know my barrel like high speed to have a good accuracy! (about 3350 fps)
I made a lot of testing with my tow cases (Norma and Lapua) with same powder, same bullet and same primer.

The conclusion : I have a better accuracy with Lapua Cases!.

I have more Neck Clearance with the Norma Case (.about .006'') than the Lapua case (.003'')

Is it a rule to reduce at the minimum the Neck Clearance to improve the accuracy in 6PPC?

A+
Laurent.


lapua_10.jpg
norma_10.jpg
 
Hi Bergeon,, the less neck clearance the better for accuracy. .003 is right where you want to be. That gives .001.5" clearance on each side of neck in the chamber.

I am a huge Savage fan and shoot a 6BR Norma 8 twist 105-108 gr. bullets with a 110 Savage action getting fantastic results. I also use Wilson die's:cool:

Good shooting!
 
Less neck clearance also helps extend the life of your brass too, since your necks will not have to expand as much and work harden. Anneal if your neck's start to spring back too much after sizing.
 
Less neck clearance means less expansion of necks , so working them less when resizing. This definitely extends brass life.

As to "Is it a rule to reduce at the minimum the Neck Clearance to improve the accuracy in 6PPC?" I do not believe that is true. In two good chambers, one with say .001" per side clearance vs .003" per side clearance, as long as the necks are properly turned I do not believe you would see any significant accuracy improvement.
Dick
 
DanSavage mentions annealing. Just so I'll know, is anyone winning benchrest matches with annealed brass. The reason I ask is that there are annealing methods now that were not available years ago.
 
Dick Grosbier said:
As to "Is it a rule to reduce at the minimum the Neck Clearance to improve the accuracy in 6PPC?" I do not believe that is true. In two good chambers, one with say .001" per side clearance vs .003" per side clearance, as long as the necks are properly turned I do not believe you would see any significant accuracy improvement.
Dick
Click to expand...

Conclusion :
This would mean in my tests that the difference in accuracy between Norma cases and LAPUA, that I work in Norma case with no turn neck ?

A+
Laurent.
 
If you truly believe that one case shoots better than the other....then use the better shooting case. Make certain that you have enough clearance in the chamber to shoot what you prefer. If you aren't forced to turn the necks to attain clearance, I wouldn't do it.
 
You must log in or register to reply here.
Back
Top