does overall length really play a big part in accuracy? i know most people go buy the book, but what is the best way to determine the correct oal when reloading? can somebody please help me???? i have a stoney point guage. is this the best way?????
COL can make a difference. Does it always? Not necessarily. I only have one rifle, out of 5, that shoots best with the COL given out of the reloading manuals. Most shoot better with a longer COL. I have one that I have to actually have a shorter COL because the magazine/clip will not allow anything that length or longer. The Stoney point is what I use and it works well. But the 1st thing I measure is the magazine and what length cartridge it will allow. Then I measure the chamber of the rifle and go from there. Something ,sometimes, as important as COL is the OGive measurement. Stoney Point alsos makes a little device that will measure this. Hope this helps.
Oal can make a big difference in the accuracy of a round. The Stoney Point is a good tool for measuring your OAL but, it won`t tell you what it should be, only what it is.
The term CORRECT OAL is a bit misleading. The best OAL is not a fixed, cut in stone rule or lenght, but one where your rifle and ammo preform at their optimum capacity. The "correct" OAL is one that fits in your magazine, feeds properly and produces safe cartridges.
There are a couple of thoughts on how to seat a bullet for the best result. The benchrest crowd likes to jam the bullet in the rifleing. This gives them a uniform tension for the bullet to overcome on ignition helping to produce more uniform velocities and pressures. Barnes with their solid copper bullets recommend seating .050" off the lands to keep pressures from spikeing. Then there is the view that all hunting ammo should be .010" or so off the lands to prevent haveing the bullet stick in the leade while in the field when one tries to unload his chamber after the hunt. The last, which most I know adhere to is that a rifle will shoot best with a defined amount of "jump" to the lands. The amount will vary from rifle to rifle and may change over time if the throat wears from use. There is no way to predict what it is and one must try different OALs until he finds the one that suits his rifle best.
When I start out to load for a new rifle I find the rifleing with my Stoney Point Gauge and work up my load with this lenght. When I find the max load for my rifle I drop it a grain and start shortening the OAL .005" at a time. I load 5 rds at each increment although 3 will probably work and fire them from the bench looking for the load that seems to be the most accurate. When I think I`ve found it I load 10 more at that lenght (useing the stoney point to set it) and 5 at .010 under and 5 at .010 over and see if the results repete. If the load seems to still be the most accurate I record the OAL as read on the Stoney Point and try to return to the max pwder charge I originally had. This should be the OPTIMUM OAL for that rifle as long as it fits the magazine and feeds.
In the future the OAL shown on the Stoney Point is the lenght I start with for all bullets I work with reguardless of style or brand. I just adjust the OAL up or down a couple of .005" lenghs to verify I`m at the best lenght for that bullet.
Hope I not rambling and this isn`t confusing you........
If you have opportunity take several different manufacturers cartridges, using the same bullet and measure them. The OAL/COL will be different for every one of them. I guess I should refrase what I said in my last post. OAL/COL is always important or you could load a cartridge of a 308 length into a rifle with a 7mm Rem chamber and it would shoot fine. What I am talking about is that often rifles will shoot MOA or better with several different OAL/COL lengths of the same cartridge. Some rifles may be very picky but many are not.
I agree with the previous replies. My rifles tend to shoot a little better when I seat the bullet about as long as the magazines will alow, or .010" from th e riflings. I wouldn't recomend getting any longer than .010" from the riflings.
Another think to keep in mind is the psi is going to go up as you cut down the gap from the bullet to the riflings. As you lenghthen a cartridge, you should also back down the powder slightly. I figured this out last weekend the hard way when my 223 started showing signs of high psi. I decided to try some rounds with the bullet seated about .007" longer. I kept the same powder charge, and consequently had too much psi.
