Maximum length for rifle round

[Jambo]

I got 9mm loading fairly well down and having fun with it. I want to start loading .243 Winchester rounds and have gotten most of the components for it.

I measured the OAL for my Remington 700 to the rifling and I came up with a length TO the rifling of 2.747 using the Speer #1220 projectiles I am planning on loading with.

My question is that the MAXIMUM OAL as published is 2.710 which leaves a difference of .037 if I want to load to maximum length for best accuracy. To me, being a hobby machinist, that is quite a large difference and I am not sure about loading to the length. It looks like I will have no problem using that length in the magazine and it should fit fine but I am not sure about any other issues. It also seems as if the projectile will have a full seat on the neck of the cartridge at that length. It is a boat-tail bullet and the boat-tail starts right at the case neck transition.

Any help, advice or "your doing it wrong stupid" would be very much appreciated!!!

Thanks!!!

[Mad Russian]

Maximum accuracy doesn't always depend on seating the bullet against the lands. Some bullets require that jump. Best way to find the sweet spot is to experiment.
Load 10 rounds at spec OAL, then ten rounds that are closer to the lands. At some point you will find what works for your rifle.

[FastPhil]

I try to load. 010 from the lands . Also depends if the bullet has a canilure or not. The books say loading to the lAnds can increase pressures to dangerous levels. If a round is a little off you may have trouble closing the bolt

[Bigrob]

Hornady makes a couple products that help you find the optimal bullet seat depth without to much experimintation.

[Jarheadsergeant]

Reloading rifle and pistol ammunition are entirely different animals.

The published COAL you are referring to is a voluntary standard from SAAMI. This is a standard the industry agreed upon so that the amminiton and firearms would hopefully work together across various manifactuers.

Your condition is common. This is the result of the point at which the bearing surface on the bullet engages the rifling. In general, tangent ogive bullets, like the one you are loading for, aren't particularly senstive to the amount they jump from the case to the rifling. Secant ogive bullets, think VLD, are. In those cases, guys will get into a crazy amount of tuning to get them to shoot, either running a .010" jam al the way back to a .130" jump. In Berger's load manual, they recommend testing in intervals of .040"! Most common of the commonly encountered, and popular bullets are easy to tune. If you start doing a lot of load development and shoot mulriple 5 and 10 shot groups, you'll see the OAL matters less than you've been lead to believe for most bullets. We'd normally establish a baseline for a lowd with a powder and fine tune OAL at the end. Outside of benchrest guns, for most bullets, most of use will not notice much of a difference.

A few more notes:

COAL effects pressure. Read up on the combined gas law.

COAL effects how much powder you can get into a case. This is why a lot of guys run long throats in match guns. More powder can mean more velocity.

COAL effects how a round is fed from a magazine. Normally when I load from a rifle, I measure the magazine first! This is the case for a deatchable mag or for a fixed mag inside the gun. I'll take the rifle apart and measure it.

COAL can be determined by whether or not a bullet has a caaneulure as stated above.

Note the bullet you are shooting seems to be a soft point. OAL to the tip of the cartridge is unreliable for this. Try getting a gauge that measures to the ogive to aboid false readings.

[Jarheadsergeant]

[Postal Bob]

I load all my rifle loads 1/16" from the rifling. Each gun is specific for the load. Just take a fired cartridge, pinch the neck slightly to hold the bullet with a little tension. Push the bullet in just enough to hold in place. Carefully load the shell into the gun, and then remove, being careful not to disturb the bullet. Measure the oal. Then deduct 1/16" for the oal to use in that particular rifle.

[Havfun]

I load all my rifle loads 1/16" from the rifling. Each gun is specific for the load. Just take a fired cartridge, pinch the neck slightly to hold the bullet with a little tension. Push the bullet in just enough to hold in place. Carefully load the shell into the gun, and then remove, being careful not to disturb the bullet. Measure the oal. Then deduct 1/16" for the oal to use in that particular rifle.

nice tip

[cas]

The best OAL for your rifle, accuracy wise may be way too long for your magazine. I've been there with Rem 700's.

[Jambo]

Everyone, thanks for all the great info, I have been reading and studying the Internet based on all the great information above.