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-   Reloading (https://www.huntingnet.com/forum/reloading-15/)
-   -   308 accuracy load (https://www.huntingnet.com/forum/reloading/291026-308-accuracy-load.html)

Scott Gags 04-06-2009 03:34 AM
RE: 308 accuracy load
 
ORIGINAL: stubblejumper

The magnum primers will decrease the effective burn time and increase velocity. I gain over 100 fps in my 06 when switching from 210 to 215 primers with 180 grain bullets. This should work in any case capacity limited cartridge.
Of course the extra velocity is a result of extra chamber pressure produced when using the 215s.You can simply use 210 primers,and add a grain or two of powder to achieve the same results.
I guess I misunderstood the posts above. I understood the problem with 4350 in the 308 was that it reached max case capacity before it reached rated pressure and there was no room to add a grain or two of powder as you suggested. That is also why I specified "case capacity limited cartrigde" in my post above. RL22 in my 06 required heavy compression in order to get good velocities with some bullets. When I switched to the 215 primers I got the desired pressures without heavy compression of the powder. I dont load for the 308 but it seemed to me like the same situation for Shoulder Strap.

bigcountry 04-06-2009 06:35 AM
RE: 308 accuracy load
 
ORIGINAL: Scott Gags

ORIGINAL: stubblejumper

The magnum primers will decrease the effective burn time and increase velocity. I gain over 100 fps in my 06 when switching from 210 to 215 primers with 180 grain bullets. This should work in any case capacity limited cartridge.
Of course the extra velocity is a result of extra chamber pressure produced when using the 215s.You can simply use 210 primers,and add a grain or two of powder to achieve the same results.
I guess I misunderstood the posts above. I understood the problem with 4350 in the 308 was that it reached max case capacity before it reached rated pressure and there was no room to add a grain or two of powder as you suggested. That is also why I specified "case capacity limited cartrigde" in my post above. RL22 in my 06 required heavy compression in order to get good velocities with some bullets. When I switched to the 215 primers I got the desired pressures without heavy compression of the powder. I dont load for the 308 but it seemed to me like the same situation for Shoulder Strap.
Actually, I think you are correct. Problem with 4350 or H4831sc in the 308 case is not pressure but capacity. You will always be compressed. I have to admit, I have never tried a mag primer with these slow burners. I might have too. Good call.

stubblejumper 04-06-2009 07:17 AM
RE: 308 accuracy load
 
Actually, I think you are correct. Problem with 4350 or H4831sc in the 308 case is not pressure but capacity. You will always be compressed. I have to admit, I have never tried a mag primer with these slow burners. I might have too. Good call.
The problem is that using magnum primers in the smaller cases,often provides less than optimum accuracy.I would simply choose a more suitable powder to gain velocity.

bigcountry 04-06-2009 07:39 AM
RE: 308 accuracy load
 
ORIGINAL: stubblejumper

Actually, I think you are correct. Problem with 4350 or H4831sc in the 308 case is not pressure but capacity. You will always be compressed. I have to admit, I have never tried a mag primer with these slow burners. I might have too. Good call.
The problem is that using magnum primers in the smaller cases,often provides less than optimum accuracy.I would simply choose a more suitable powder to gain velocity.
Your right also. The issue is, I have found amazing accuracy with 4350 and 308 case. But lacking about 100-200fps of velocity you would expect. So I for instance love sub 0.5MOA accuracy, I would love to get the velocity Varget or 4064 gives you.



Scott Gags 04-06-2009 01:02 PM
RE: 308 accuracy load
 
ORIGINAL: stubblejumper

Actually, I think you are correct. Problem with 4350 or H4831sc in the 308 case is not pressure but capacity. You will always be compressed. I have to admit, I have never tried a mag primer with these slow burners. I might have too. Good call.
The problem is that using magnum primers in the smaller cases,often provides less than optimum accuracy.I would simply choose a more suitable powder to gain velocity.
Myrifles accuracy improved slightly, that isone reasonI recommended it. I was quite pleased with the resultsfrom such a simple change.I find itrewarding to to try something a little unconventional and get a positive result. I just wish it happened more often.[&o]

stubblejumper 04-06-2009 01:37 PM
RE: 308 accuracy load
 
Myrifles accuracy improved slightly, that isone reasonI recommended it. I was quite pleased with the resultsfrom such a simple change.I find itrewarding to to try something a little unconventional and get a positive result. I just wish it happened more often.[&o]
The odds of 308win accuracy increasing with a change to a magnum primer are low,occurring most commonly with ball powders.In most cases,the best accuracy is achieved with a primer that is just hot enough to provide consistent ignition of the powder.

The magnum primers will decrease the effective burn time and increase velocity.
Not according to:

http://findarticles.com/p/articles/mi_m3197/is_n8_v34/ai_7903615/pg_2/

From that link:

To begin, the main difference between a standard-force and a magnum-force primer is in the length of its burning time. A magnum-force primer burns longer than a standard force and therefore tends to increase chamber heat variously depending upon the primer's own power, the powder involved, and cartridge case size plus bullet weight.

bigcountry 04-06-2009 05:15 PM
RE: 308 accuracy load
 
ORIGINAL: stubblejumper

Myrifles accuracy improved slightly, that isone reasonI recommended it. I was quite pleased with the resultsfrom such a simple change.I find itrewarding to to try something a little unconventional and get a positive result. I just wish it happened more often.[&o]
The odds of 308win accuracy increasing with a change to a magnum primer are low,occurring most commonly with ball powders.In most cases,the best accuracy is achieved with a primer that is just hot enough to provide consistent ignition of the powder.

The magnum primers will decrease the effective burn time and increase velocity.
Not according to:

http://findarticles.com/p/articles/mi_m3197/is_n8_v34/ai_7903615/pg_2/

From that link:

To begin, the main difference between a standard-force and a magnum-force primer is in the length of its burning time. A magnum-force primer burns longer than a standard force and therefore tends to increase chamber heat variously depending upon the primer's own power, the powder involved, and cartridge case size plus bullet weight.
I think what Scott is trying to explain is if you use a slow powder like 4350, magnum powders could ignite more consistently. It makes sense.

But the bottom line is, its worth a try, and if it doesn't work, ok, you tried something and learned something in the process.

Scott Gags 04-06-2009 06:14 PM
RE: 308 accuracy load
 
The odds of 308win accuracy increasing with a change to a magnum primer are low,occurring most commonly with ball powders.In most cases,the best accuracy is achieved with a primer that is just hot enough to provide consistent ignition of the powder.
Generally I try not to buy into everything I read, but Per the article you referenced:

As a rule of thumb, standard-force primers have been recommended for all rifle situations except those employing ball-type powders and those using more than fifty grains of slow-rate extruded powder such as IMR-4350, H-4831, and IMR-7828.
Max charges in the 308 would exceed 50 grains of imr4350 with 150 grain bullets even when limited SAMMI OAL. My nosler manual lists 52 grains of imr4831 with 150/155 grain bullets and 50 grains of imr4350 with the 180s.That would seem to indicate that magnum primers are actually what the author is recommending for this situation in the article.

quote:
The magnum primers will decrease the effective burn time and increase velocity.
To begin, the main difference between a standard-force and a magnum-force primer is in the length of its burning time. A magnum-force primer burns longer than a standard force and therefore tends to increase chamber heat variously depending upon the primer's own power, the powder involved, and cartridge case size plus bullet weight.
Stubble I thinkyou misunderstood my post based on the quote you pasted above. I was not referring to the primer burn time, I was referring to the cartridge burntime or powder burn rate.

We can go round and round forever regarding accuracy the bottom line is summed up bestin the article you referenced.

Changing to a magnum-force primer, on the other hand, might run up quick, stiff chamber pressures which bring the individual barrel closer to its best vibration pattern for uniformity. Or, in some instances, the quicker jolt of chamber pressure from a magnum primer could have the reverse effect and inject greater irregularities in vibrations than the standard ones. You simply never know how they'll all work unless you try them, because each rifle is a physical law unto itself; for the molecular structure in each barrel can be different from that of any other barrel, even if the bore and cambering are identically cut.
The quote above from the article youreferencedseems to indicate that primer selection is a flip a coin affair for the most part between magnum and standard primers. Getting back to my original post I recommended the magnum primers to increase velocity in the 308 with 4350 notto increaseaccuracy in the 308. Only his rifle will determine which is actually more accurate but an increase in velocity is almost certain in my experience.

stubblejumper 04-06-2009 06:29 PM
RE: 308 accuracy load
 
My nosler manual lists 52 grains of imr4831 with 150/155 grain bullets and 50 grains of imr4350 with the 180s.That would seem to indicate that magnum primers are actually what the author is recommending for this situation in the article.
Except that the Nosler data is for the 210 primer.Substituting a 215 primer will increase chamber pressure.Nosler does not list pressures,so we don't know what the pressure is for the imr4350 loads.That might be safe for the 150gr bullets,but my Lyman manual lists the pressure for the 180gr load right around the SAAMI design pressure with the standard large rifle primer.Substituting a magnum primer,could cause pressure issues.

Stubble I thinkyou misunderstood my post based on the quote you pasted above. I was not referring to the primer burn time, I was referring to the cartridge burntime or powder burn rate.
The powder burn rate is fixed by the powder itself,not by the primer.Once the powder is ignited,it will burn at the designed rate.The magnum primer adds more heat,and therefore creates more pressure,it doesn't change the burn rate of the powder.

bigcountry 04-06-2009 07:21 PM
RE: 308 accuracy load
 
ORIGINAL: stubblejumper

My nosler manual lists 52 grains of imr4831 with 150/155 grain bullets and 50 grains of imr4350 with the 180s.That would seem to indicate that magnum primers are actually what the author is recommending for this situation in the article.
Except that the Nosler data is for the 210 primer.Substituting a 215 primer will increase chamber pressure.Nosler does not list pressures,so we don't know what the pressure is for the imr4350 loads.That might be safe for the 150gr bullets,but my Lyman manual lists the pressure for the 180gr load right around the SAAMI design pressure with the standard large rifle primer.Substituting a magnum primer,could cause pressure issues.

Stubble I thinkyou misunderstood my post based on the quote you pasted above. I was not referring to the primer burn time, I was referring to the cartridge burntime or powder burn rate.
The powder burn rate is fixed by the powder itself,not by the primer.Once the powder is ignited,it will burn at the designed rate.The magnum primer adds more heat,and therefore creates more pressure,it doesn't change the burn rate of the powder.
Thats why us reloaders are supposed to work up a load. Not take advise from the internet and start loading that. As a good rule of thumb stubble, we start 10% below max.


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