A question of theory and MV

bpost

September 23, 2009 13:17

Lets use the ubiquitous 38 spl. for this discussion. We all know there are many suitable powders for the 38 special. If we take ten different powders and load the cartridge to a nominal 775 FPS with each powder will accuracy and POI be identical?

It would seem that a MV of 775 FPS, across the board, would give an identical accuracy result regardless of the powder used; is that a correct assumption?

What are your thoughts?

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  Rocky Raab

  September 23, 2009 13:25

  Nope. I do cartridge/load workups as a writer. It is rare to the point of unheard of for two loads to group the same or hit exactly the same POI even when launched at the same speed.
  
  Different powders will affect the gun in different ways. Barrel harmonics, recoil path and quickness, and gas volume at bullet exit are only three of many variables afffected by propellant choice.

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  perry shooter

  September 24, 2009 13:57

  Hello Bpost first off lets stipulate if from a rest or from your hand. I have done extensive testing on 45 ACP from ransom rest and my finding may be different from others and sure to be different then shooting offhand one handed . I have found that a given brand and weight of bullet WILL shoot to the same point from the same gun with different powders loaded to produce the same velocity . I also found that if you find a SWEET Spot in group size with one powder you can duplicate this same sweet spot if all you change is the powder but load to the same velocity. With 45 ACP I load fast powders V.V. 310 or Bulls-Eye I like the best . very slow powders I can get the same 800- 810 FPS but never the group size as with fast powders . I attribute to the fact that MAYBE the barrel is starting to unlock before the bullet leaves the barrel. Different bullets of course have different sweet spots in my Ball guns anything less then 820 will destroy group size at 50 yards. the difference at25 yards between 700 and 830 with 230 grain is almost nothing but at 50 group size is about 4 to 1 in favor of the small group at 830 FPS. Now out of your hand recoil will make the barrel start to rise so if one could measure time between primer strike and barrel time even with the same muzzle velocity I suspect the barrel time is greater with slower burning powders NONONSENCE is really up on this subject but I think more in the rifle cartridges.

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