Reloading a new caliber from new brass

[Icefire]

Hi,
I bought a new precision rifle and a press, been reloading for pistol before.
My question is about sizing. I'll be full lenght sizing my 300 win mag, with redding die and I'll probably get a redding shellholder kit.

I bought Hornady brass and do not have any once fired.

How do you know it's resized correctly? I do have a case gauge but they already fit good.

Better to get the shellholder kit, setup the +0.010 and do a resize only for the neck tension?

 

[rick357]

Load it up with a minimum load for the powder and bullet combo you have. You don't need to size anything at this point. Take it out and shoot. Once you have fired them in your new rifle they will really be 'once fired' AND most importantly fire-formed to your rifle's chamber. I would strongly suggest using a Lee neck sizing collet, so that neck turning is not necessary. You can reload once again at whatever powder grain increment and method to search for your rifle's accuracy node. After the second firing you will probably have to at a minimum, bump the shoulder and trim to length, if not full length resize. If you are starting out bottleneck reloading with a 300WM, I wish you the best of luck. Belted magnums can be some of the most difficult cartridges to do correctly.

 

[fingers284]

I resize all new brass...mostly it is a redundant operation but you get the odd piece that benefits because some get a bit out of shape from shipping & packing operation, out of round case mouth is the most common problem.

 

[Dogleg]

Hi,
I bought a new precision rifle and a press, been reloading for pistol before.
My question is about sizing. I'll be full lenght sizing my 300 win mag, with redding die and I'll probably get a redding shellholder kit.

I bought Hornady brass and do not have any once fired.

How do you know it's resized correctly? I do have a case gauge but they already fit good.

Better to get the shellholder kit, setup the +0.010 and do a resize only for the neck tension?

The easiest and best thing you can do is get the Redding shellholder set. Use the .010" right from the beginning and don't even think about doing anything else until after a few loadings when (if ever) the loaded cartridges start chambering with a bit too much effort. At that point go through the set until you either get just a hint of resistance or none. Your choice. (psst, factory rifle its going to be .004", but you never heard it from me).

You don't need the case gauge; you have the rifle. The gauge compares to an arbitrary standard, the rifle is the rifle. You don't shoot the gauge.

Its a little like feet. You can get you feet measured and come up with a number. It's something.

Or, you can try the boots on. That's everything.

 

[Icefire]

rick357 The last owner of the rifle sold me his redding S Match Die with it (FL bushing die + Comp. seater). He gave me the recipe of 1/4 MOA ammo he was making for it. I would normally take that as cash but the brand new brass have me puzzled.

Normally I would only resize to bump the shoulder about .001 or so, trim if needed.

Turning is optional AFAIK with those die?

 

[8x68]

Don't forget to check the flash hole for burrs. Could affect accuracy if you get into match competitions. On any new brass I use a flash hole deburring tool. That's just me.

 

[Icefire]

Don't forget to check the flash hole for burrs. Could affect accuracy if you get into match competitions. On any new brass I use a flash hole deburring tool. That's just me.

Good point, I do have primer pocker reamers but I'll check if I got the flash hole deburing tool.

 

[rick357]

rick357 The last owner of the rifle sold me his redding S Match Die with it (FL bushing die + Comp. seater). He gave me the recipe of 1/4 MOA ammo he was making for it. I would normally take that as cash but the brand new brass have me puzzled.

Normally I would only resize to bump the shoulder about .001 or so, trim if needed.

Turning is optional AFAIK with those die?

Not saying the full length bushing die won't work, but is not optimal. Any variation in case neck wall thickness stays when neck sizing and the bullet is therefor seated off-center. Whether this makes a difference to your rifle and your expectation of its accuracy is up to you. I would be very wary of using the Redding competition shellholder set as well. When you use the 0.010 or any shellholder which doesn't push the casing fully into the full length die, you will not be full length sizing the case. Now on a .223 it really doesn't matter a whole lot, neither does it on my 6.5CM, nor on either of my .308, since the case fits up into the die well past where the webbing ends, but on my 300WM it does, in a big way. Most dies just do not size right up to the belt on these magnum cases very well. I include the 7mmRM or any belted magnum in this discussion as well. The less it is shoved up into that full length die, the less that gets sized just above the belt. This also happens to be above where the webbing ends and is where the case wall is into the body past the webbing. Failure of the case at this point is a known issue. Yes, a shoulder bump based on the shoulder to base length and NOT on the shoulder to belt length is necessary to reduce or eliminate successive stretching and compression resulting in eventual head separation. Unfortunately a full body length size will put that case back to some sort of SAAMI length, will likely be excessive for your rifle, and will have a detrimental effect by shoving the shoulder back too far. Backing off the amount the case is full length resized will maintain proper headspace and shoulder position but will result in a section of casing which does not get resized properly just above the belt and results in case bulging at this point. Kind of between a rock and a hard place at this point.

Have a look at this asap: youtube.com/watch?v=iKhwHBaSlXQ

Great explanation with video. I have this die and it DOES work. I size to 0.0015 thou shoulder bump with my Forster body die (no neck sizing) and have to use Larry's die about every 3 reloads. The only other way around this is to toss the brass when they won't chamber - and that doesn't take very long - somewhere around reload #3 or 4. The other way is to full length size shoving the shoulder back so that the belt bulge is minimized or eliminated and check for stretch/wall thinning and toss the brass. This initially showed up at reload #4 with my 300WM. Your results may differ.