Short barrel and burn rates....

DGY

DGY

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Good day all!
So here is a question that might be obvious to some, for exemple, I have 3 30-06 in two barrel length, one is 20” and the other two 22”, for a same bullet weight would the 20” barreled rifle benefit a faster burning powder to achieve best performances?
 
The burning and peak pressure is over in a few inches. All that happens after that is acceleration from the pressure. Whatever powder is best for a 150 gr bullet would be best in a 16" barrel and best in a 28" barrel. Same for a 180 gr bullet, but it would be a different powder than for the 150.
 
X6

Five years ago (and even more recently) there were fierce dissagreements on CGN between "Short Barrel - Fast Powder, Long Barrel - Slow Powder" Flat Earth types and those who were correct, and at times threads were locked as a result. Calm, data-driven arguments seem to have uprooted that long-held myth - on CGN anyways.

I have to admit, I never thought this would happen in my lifetime.
 
I agree with the fact that relatively slower burning powders produce the fastest bullet speeds regardless of barrel length. But "performance" means different things to different people. Sometimes, depending on the rifle accuracy may be better with a certain powder. And occasionally that is a faster burning one. So that's one reason to consider the possible use of a faster burning powder than what the book indicates as "best".

The main reason that prompts me to use somewhat quicker burning powders in short barrels is muzzle blast. I really hate muzzle blast. I wear hearing protection almost always anyway, but the blast from a slow powder shot in a short barrel is noticeably more than the blast produced by a quicker burning powder from the same barrel. Ball powder often produces more blast than extruded powder too, but the difference is small.

I'd rather shoot something like Benchmark or VV N140 out of my 20" barrel .308 than W760. I give up a little speed, maybe 50 fps, but get a nicer load to shoot and very good accuracy.
 
Longwalker said:
I agree with the fact that relatively slower burning powders produce the fastest bullet speeds regardless of barrel length. But "performance" means different things to different people. Sometimes, depending on the rifle accuracy may be better with a certain powder. And occasionally that is a faster burning one. So that's one reason to consider the possible use of a faster burning powder than what the book indicates as "best".

The main reason that prompts me to use somewhat quicker burning powders in short barrels is muzzle blast. I really hate muzzle blast. I wear hearing protection almost always anyway, but the blast from a slow powder shot in a short barrel is noticeably more than the blast produced by a quicker burning powder from the same barrel. Ball powder often produces more blast than extruded powder too, but the difference is small.

I'd rather shoot something like Benchmark or VV N140 out of my 20" barrel .308 than W760. I give up a little speed, maybe 50 fps, but get a nicer load to shoot and very good accuracy.
Click to expand...

YES!!

I have a 308 with a 16" barrel. Some powders have a muzzle blast (I call it a "bark") that is very painful.

The "bark" is caused by gasses igniting when they hit the air. Some powders do it. Some don't. The "bark" is so obnoxious that there is no redeeming value. It would not matter how fast or accurate the load is. IT is just unacceptable. I have not been able to pin point the cause of the blast. I suspect that it has more to do with the chemistry of the powder (additives) than the speed. That is, switching from 4350 to 3031 may not be the solution.

If you have a short barreled rifle, you would want to do a load development (as usual) and pay attention to this issue before you invest much time in the project with this powder. If it "barks" - move on to something else.

22" is not "short" by my definition. But the wrong powder might bark. If you have 2 rifles, each requires its own work up to see what it likes. By all means start with the same powder and find the "accuracy" load for each. If there is a compromise possible, where booth can shoot the same ammo, good.

22"
 
Code: 
Cartridge          : [B].30-06 Spring[/B].  (SAAMI)
Bullet             : .308, 168, Nosler BalTip 30168
Useable Case Capaci: 61.620 grain H2O = 4.001 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
[B]Barrel Length      : 18.0 inch[/B] = 457.2 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 55000 psi, or 379 MPa
or a maximum loading ratio or filling of 104 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

119 loads produced a Loading Ratio below user-defined minimum of 80%. These powders have been skipped.
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Alliant Reloder-17                  94.1     56.1     3.63    2702    99.0    55000   13781   0.952  ! Near Maximum !
Alliant Reloder-16                 100.7     55.7     3.61    2675    98.3    55000   13531   0.961  ! Near Maximum !
Ramshot Hunter                      98.7     57.9     3.75    2648    95.3    55000   13508   0.961  ! Near Maximum !
Alliant Reloder-19                 103.1     58.6     3.80    2634    91.8    55000   13464   0.957  ! Near Maximum !
Hodgdon H414                        92.9     55.8     3.62    2633    94.2    55000   13388   0.966  ! Near Maximum !
Winchester 760                      92.9     55.8     3.62    2633    94.2    55000   13388   0.966  ! Near Maximum !
Hodgdon Hybrid 100V                100.8     55.4     3.59    2624    98.9    55000   12503   0.964  ! Near Maximum !

Code: 
Cartridge          : [B].30-06 Spring. [/B] (SAAMI)
Bullet             : .308, 168, Nosler BalTip 30168
Useable Case Capaci: 61.620 grain H2O = 4.001 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
[B]Barrel Length      : 28.0 inch [/B]= 711.2 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 55000 psi, or 379 MPa
or a maximum loading ratio or filling of 104 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

119 loads produced a Loading Ratio below user-defined minimum of 80%. These powders have been skipped.
Powder type          Filling/Loading Ratio  Charge    Charge   Vel. Prop.Burnt P max  P muzz  B_Time
                                      %     Grains    Gramm   fps     %       psi     psi    ms
---------------------------------  -----------------------------------------------------------------
Alliant Reloder-17                  94.1     56.1     3.63    3002   100.0    55000    8006   1.243  ! Near Maximum !
Alliant Reloder-16                 100.7     55.7     3.61    2972    99.9    55000    7901   1.255  ! Near Maximum !
Ramshot Hunter                      98.7     57.9     3.75    2950    98.6    55000    8131   1.257  ! Near Maximum !
Alliant Reloder-19                 103.1     58.6     3.80    2939    96.1    55000    8237   1.255  ! Near Maximum !
Winchester 760                      92.9     55.8     3.62    2934    97.8    55000    8072   1.264  ! Near Maximum !
Hodgdon H414                        92.9     55.8     3.62    2934    97.8    55000    8072   1.264  ! Near Maximum !
Hodgdon Hybrid 100V                100.8     55.4     3.59    2904   100.0    55000    7234   1.264  ! Near Maximum !


Note the order of powders generating best speeds don't change from 18" to 28"
 
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