Postal Shoot, factory ammo help
Posted: Fri Jul 13, 2007 6:43 pm
The 204 Ruger forum Postal Shoot is an exciting activity just on the horizon. I have read a couple of posts where some members feel they will be handicapped shooting factory ammo. You don't have to be as handicapped as you think. Here are some tips for wringing out the best performance possible from factory ammo.
Run Out –
One thing that most have found aids accuracy is controlling run out. Even though you can’t control run out in factory ammo, short of some corrective realigning of the bullet, you can still sort your ammo by run out. Measure the run out of your factory ammo. Anything with more than .001 run out should be culled out of your selection. Even if you don’t have a concentricity gauge you can still check for excessive run out by rolling your ammo across a flat surface. Watch the very tip of the bullet as the cartridge rolls. If it wobbles, toss it to the side. You could use those for sighters. Now you have eliminated one variable from your ammo selection.
Lot Number –
Since we will be shooting at three targets for score you may have to go through more than one box of ammo to find enough cartridges for your fifteen shots. Different runs of factory ammo might use different components such as primers or brass with varying thickness. To reduce the probability of large variances from lot to lot, try to buy several boxes of ammo that all have the same lot number. This should keep velocities and pressures more consistent. Consistency is the name of the game.
Weight Sorting –
If you have a scale, weigh each round and sort your match sets by weight. Any cartridge that is more than .5 grain heavier or lighter should be culled from your selection. You should end up with three groups of five rounds. Every round in each group of five should be no more than .1 grain off. Each group of five should be no more than .1 grain different that the other two groups. Now you have eliminated one more variable.
Length Sort –
Even though the 204 Ruger tolerates a little jump to the lands, you should try to keep all your ammo within a fixed Overall Length (OAL) from base to tip. Using a comparator would be even better than measuring from base to tip. It would be best if all your rounds fell within .003 variance.
You may have to sort and re-sort your ammo several times to get three sets of five shots very close in each of the categories mentioned above. This is why you should start with several boxes of ammo. After all, this is an aggregate competition. That means that one small group isn’t going to win. You will have to shoot three small groups to be averaged for an overall aggregate score. The winner will be the shooter that can consistently shoot three small groups. A tie breaker will be decided by the groups most centered in the bulls eye so it would pay for you to zero your scope on the day you shoot. To do that correctly, you are probably going to need a couple more three shot groups. I never shoot one shot and start moving my scope. I shoot a three shot group, measure where the center of the group is and move the center of the group. The reason I do it that way is because my three shot group is a better indication of where the center of errors is. In other words, a three shot group usually reveals my mistakes plus wind conditions. If I normally make a mistake in breathing or trigger control that affects my groups, I will probably make the same mistake while shooting for score. Therefore, it makes more sense to move the whole group than it does to shoot one shot and zero the scope. Besides, how do I know if one shot wasn’t affected by the wind conditions? Consistency is the name of this game. You can stack the odds in your favor if you’re willing to do a little homework before the shoot.
Another tip:
Don’t drink coffee on the day of the shoot. Coffee is a known group killer. Now get out there and do some practicing.
Run Out –
One thing that most have found aids accuracy is controlling run out. Even though you can’t control run out in factory ammo, short of some corrective realigning of the bullet, you can still sort your ammo by run out. Measure the run out of your factory ammo. Anything with more than .001 run out should be culled out of your selection. Even if you don’t have a concentricity gauge you can still check for excessive run out by rolling your ammo across a flat surface. Watch the very tip of the bullet as the cartridge rolls. If it wobbles, toss it to the side. You could use those for sighters. Now you have eliminated one variable from your ammo selection.
Lot Number –
Since we will be shooting at three targets for score you may have to go through more than one box of ammo to find enough cartridges for your fifteen shots. Different runs of factory ammo might use different components such as primers or brass with varying thickness. To reduce the probability of large variances from lot to lot, try to buy several boxes of ammo that all have the same lot number. This should keep velocities and pressures more consistent. Consistency is the name of the game.
Weight Sorting –
If you have a scale, weigh each round and sort your match sets by weight. Any cartridge that is more than .5 grain heavier or lighter should be culled from your selection. You should end up with three groups of five rounds. Every round in each group of five should be no more than .1 grain off. Each group of five should be no more than .1 grain different that the other two groups. Now you have eliminated one more variable.
Length Sort –
Even though the 204 Ruger tolerates a little jump to the lands, you should try to keep all your ammo within a fixed Overall Length (OAL) from base to tip. Using a comparator would be even better than measuring from base to tip. It would be best if all your rounds fell within .003 variance.
You may have to sort and re-sort your ammo several times to get three sets of five shots very close in each of the categories mentioned above. This is why you should start with several boxes of ammo. After all, this is an aggregate competition. That means that one small group isn’t going to win. You will have to shoot three small groups to be averaged for an overall aggregate score. The winner will be the shooter that can consistently shoot three small groups. A tie breaker will be decided by the groups most centered in the bulls eye so it would pay for you to zero your scope on the day you shoot. To do that correctly, you are probably going to need a couple more three shot groups. I never shoot one shot and start moving my scope. I shoot a three shot group, measure where the center of the group is and move the center of the group. The reason I do it that way is because my three shot group is a better indication of where the center of errors is. In other words, a three shot group usually reveals my mistakes plus wind conditions. If I normally make a mistake in breathing or trigger control that affects my groups, I will probably make the same mistake while shooting for score. Therefore, it makes more sense to move the whole group than it does to shoot one shot and zero the scope. Besides, how do I know if one shot wasn’t affected by the wind conditions? Consistency is the name of this game. You can stack the odds in your favor if you’re willing to do a little homework before the shoot.
Another tip:
Don’t drink coffee on the day of the shoot. Coffee is a known group killer. Now get out there and do some practicing.
Skipper 
.. Good post!!
