various points of accuracy???? - The Firearms Forum

.308 shooter · 10-14-2008, 10:29 PM

I was speaking with a gentleman recently and explaining to him my groups are good, but velocity is low. I have to drop almost 2 lines on my BDC reticle from 100 to 200 yds. I was told though my initial charge (which is low) is good, and it gets worse as I go up, that it will also come into another accurate setting as I continue to go up in charge.

Is this accurate information? Does accuracy come in, go out and come in again as charges increase?

RodneyJ · 10-15-2008, 12:00 AM

Yes, from what I have read and people I have talked to this is true. I have heard the accuracy settings you are talking about refered to as accuracy nodes. The reason for the accuracy to change is due to harmonics and the bullet leaving the barrel at a different point of the barrel vibration. Form what I have read and those I have talked to at the range you may have 2 to 3 powder charges that will produce good accuracy and as you move away from these points up are down the accuracy will deminish untill you start moving into the next node. I'm sure there are others here that can explain it better than I have but I hope this helps.

.308 shooter · 10-15-2008, 06:38 AM

Thanks..... That's what I was told as well. Back to the drawing board!!

LDBennett · 10-15-2008, 07:39 AM

RodneyJ explained it correctly and well. But you may not find a node beyond where you are at now.

If max or just better velocity is needed then start changing components (like bullet, or powder) and developing a new load. The easiest in your situation might be to stick with the bullet you have selected if it performs terminally as you require and move to a different powder. A review of several manuals may show that a particualr cartridge may have an affinity for one powder over others. Start there first but don't be afraid to try others if you have not met your performance criteria. Finding the "ideal" load is an almost never ending quest as there are so many varibles to manipulate. I loose interest after about two powder choices and compromise my performance criteria as shooting for fun is more interesting to me than testing loads...that's just work to me.

LDBennett

DWARREN123 · 10-15-2008, 09:57 AM

Bad thing is they will change sometimes with changes in components and you have to start over.

LDBennett · 10-15-2008, 01:26 PM

YES, INDEED!

.308 shooter · 10-16-2008, 06:31 AM

Thanks all,
LD.... it's fun for me too. But i must admit, I find it a challenge to try different things. Who knew.....I always thought I liked taking the easy way out.

I'm not necessarily looking for more velocity, but I guess I wouldn't mind a 3-4" drop from 100 - 200 yds.... especially since I'm hoping to get to the 600 yd range soon.

Thanks again everyone.

Falconry · 12-02-2008, 07:08 PM

I discovered loading for my 06 that with 165 grain bullets I could get a 5 shot group that I could ALMOST cover with a quarter. That was with 56.4 grains of IMR 4350. Now anything else for loads much hotter or lower opened up my groups noticeably. So I like to think of it as a "cone" where you find the sweet spot for the projo/powder matrix. Some guns DON'T like certain powders and or bullet combinations. So, there is a correlation with powder,bullet and barrel harmonics for sure. My .300 WSM likes H414 and 165 grain bullets too,but didn't like the Barnes TSX as much as the Noslers. Heck it even likes the Hornadys too.
So, try different powders after doing the manuals research. Barnes actually has a good manual for load information and you don't have to use their bullets. Match bullet length to barrel twist (longer bullets need more twist to stay ballistic).
I get only 1.75" drop from 100 to 200 yards with my 06 and 1.25 with the 300 so I am curious about what type loads and velocities we are dealing with.

millwright · 12-03-2008, 12:52 PM

308, You've hit upon the real fun in reloading - internal ballistics !!

Lots of reasons for what you're observing and an important one is barrel harmonics. Another is velocity. As you increase/decrease powder charges for a given bullet weight you decrease/increase bullet "dwell time" (time its in the barrel). You also influence its spin rate - a factor in stability. Also important to accuracy in a given rifle is how the powder burns - both in rate (speed) and pressure curve development. And all these affect barrel harmonics as well......

IOW, once you get the addiction, its lifelong as the possibilities are endless and growing..... >MW

10-14-2008, 10:29 PM	#1
.308 shooter V.I.P. Member Join Date: May 2008 Posts: 100	various points of accuracy???? I was speaking with a gentleman recently and explaining to him my groups are good, but velocity is low. I have to drop almost 2 lines on my BDC reticle from 100 to 200 yds. I was told though my initial charge (which is low) is good, and it gets worse as I go up, that it will also come into another accurate setting as I continue to go up in charge. Is this accurate information? Does accuracy come in, go out and come in again as charges increase? -->

10-15-2008, 12:00 AM	#2
RodneyJ V.I.P. Member Join Date: Jan 2008 Location: Houston Texas Posts: 62	Re: various points of accuracy???? Yes, from what I have read and people I have talked to this is true. I have heard the accuracy settings you are talking about refered to as accuracy nodes. The reason for the accuracy to change is due to harmonics and the bullet leaving the barrel at a different point of the barrel vibration. Form what I have read and those I have talked to at the range you may have 2 to 3 powder charges that will produce good accuracy and as you move away from these points up are down the accuracy will deminish untill you start moving into the next node. I'm sure there are others here that can explain it better than I have but I hope this helps.

10-15-2008, 06:38 AM	#3
.308 shooter V.I.P. Member Join Date: May 2008 Posts: 100	Re: various points of accuracy???? Thanks..... That's what I was told as well. Back to the drawing board!!

10-15-2008, 07:39 AM	#4
LDBennett Advanced Senior Member Join Date: Dec 2003 Location: Hesperia, CA Posts: 5,719	Re: various points of accuracy???? RodneyJ explained it correctly and well. But you may not find a node beyond where you are at now. If max or just better velocity is needed then start changing components (like bullet, or powder) and developing a new load. The easiest in your situation might be to stick with the bullet you have selected if it performs terminally as you require and move to a different powder. A review of several manuals may show that a particualr cartridge may have an affinity for one powder over others. Start there first but don't be afraid to try others if you have not met your performance criteria. Finding the "ideal" load is an almost never ending quest as there are so many varibles to manipulate. I loose interest after about two powder choices and compromise my performance criteria as shooting for fun is more interesting to me than testing loads...that's just work to me. LDBennett

10-15-2008, 09:57 AM	#5
DWARREN123 Senior Member Join Date: Aug 2003 Location: BETWEEN TN & KY Posts: 764	Re: various points of accuracy???? Bad thing is they will change sometimes with changes in components and you have to start over. __________________ Have a nice day!

10-15-2008, 01:26 PM	#6
LDBennett Advanced Senior Member Join Date: Dec 2003 Location: Hesperia, CA Posts: 5,719	Re: various points of accuracy???? *YES, INDEED!*

10-16-2008, 06:31 AM	#7
.308 shooter V.I.P. Member Join Date: May 2008 Posts: 100	Re: various points of accuracy???? Thanks all, LD.... it's fun for me too. But i must admit, I find it a challenge to try different things. Who knew.....I always thought I liked taking the easy way out. I'm not necessarily looking for more velocity, but I guess I wouldn't mind a 3-4" drop from 100 - 200 yds.... especially since I'm hoping to get to the 600 yd range soon. Thanks again everyone.

12-02-2008, 07:08 PM	#8
Falconry Member Join Date: Dec 2008 Posts: 2	Re: various points of accuracy???? I discovered loading for my 06 that with 165 grain bullets I could get a 5 shot group that I could ALMOST cover with a quarter. That was with 56.4 grains of IMR 4350. Now anything else for loads much hotter or lower opened up my groups noticeably. So I like to think of it as a "cone" where you find the sweet spot for the projo/powder matrix. Some guns DON'T like certain powders and or bullet combinations. So, there is a correlation with powder,bullet and barrel harmonics for sure. My .300 WSM likes H414 and 165 grain bullets too,but didn't like the Barnes TSX as much as the Noslers. Heck it even likes the Hornadys too. So, try different powders after doing the manuals research. Barnes actually has a good manual for load information and you don't have to use their bullets. Match bullet length to barrel twist (longer bullets need more twist to stay ballistic). I get only 1.75" drop from 100 to 200 yards with my 06 and 1.25 with the 300 so I am curious about what type loads and velocities we are dealing with.

12-03-2008, 12:52 PM	#9
millwright Advanced Senior Member Join Date: Jun 2005 Posts: 1,440	Re: various points of accuracy???? 308, You've hit upon the real fun in reloading - internal ballistics !! Lots of reasons for what you're observing and an important one is barrel harmonics. Another is velocity. As you increase/decrease powder charges for a given bullet weight you decrease/increase bullet "dwell time" (time its in the barrel). You also influence its spin rate - a factor in stability. Also important to accuracy in a given rifle is how the powder burns - both in rate (speed) and pressure curve development. And all these affect barrel harmonics as well...... IOW, once you get the addiction, its lifelong as the possibilities are endless and growing..... >MW