Cartridge length

[Montanahunterjon]

I have a weatherby vanguard 30-06 and I have found a decent load of 55.5 gr h4350 with 180gr partitions. How important is it to adjust the length of the cartridge for accuracy? Anyone had experience with this? I've heard weatherby rifles do not like the bullets touching the lands like in other rifles. Thanks for you help, I've only been reloading a year or so and have just been a bit nervous to attempt playing with the length or COAL

 

[Southwind]

There can be a number of factors like chamber, bullet ogive and on. First off generally vld type bullets can be very particular to where their sweet spot is and a number find that touching to a few thousandths off are necessary to achieve good accuracy.

Partitions have a very forgiving ogive and jump the gap well. You may or may not gain accuracy and unless you just like to tinker it certainly isn't necessary especially if you already have a good load.

You also have to consider the length of your magazine.

 

[Redwood]

I generally find having the bullet backed off behind 1-4 thousandths is were you want to be. I start with them touching then back off and see what happens. Once I get a sweet area I do a bit more focusing in. As mentioned; make sure they fit in the mag and measure ogive. Watch your pressures if you snub it up to the rifling.

 

[jryoung]

It is certainly a variable to play with. How far off the lands are you at now? Remember, the closer you get to the lands, the more pressure you generate. So if your load is close to max, I would not suggest lengthening OAL.

Here's a great example of how adjusting in .005 increments made a significance difference (notice how he is going from longer to a shorter OAL).

 

[Montanahunterjon]

So the groups got smaller as the cartridge got shorter? That's a huge difference in accuracy though, so I guess it may be something to look into.

 

[jryoung]

All bullets vary though as some are more finicky than others. I shoot Barnes and they recommend a .050 jump to the lands. This has served me well in my reloading. If I find a load isn't working I'll play with the depth a bit more.

 

[1_pointer]

Start you load workup at the longest OAL that will fit in the magazine or chamber. This does 2 things; 1. you only have one way to go in your adjustments and 2. as alluded to above, it won't increase pressure as you change OAL. I agree that it's something to work with, but if what you have now is good enough, then I'd stop there and just work on shooting from field positions.

The deal with Weatherby's not liking being close to the lands has to do with the Weatherby rounds which have lots of freebore. This makes it impossible to get close to the lands and still fit in the magazine. 30-06's of any maker should not have this problem.