Shoulder bump or neck size?

[rookhawk]

I’m not a handloader obsessed with accuracy, seeking .250” groups so you’ll have to take my advice for what it is, expertise getting safari rifles and stalking rifles to shoot properly.

Many of my rifles have been in calibers that really predated SAAMI and were not really made to CIP specs either. Examples of these types of cartridges include 318WR, 333J, 350R, 360NE, etc, etc.

The chronic problem with these old guns is both accuracy and also incipient head separation. What I do is as follows:

1.) If a Mauser action type or similar, remove the firing pin and lock it in a safe, away from the firearm.

2.) Insert a piece of brass in the rifle and see if you can close the bolt on the brass by feel with the firing pin removed.

3.) If no, screw down the sizing die and repeat step 2 over and over.

4.) When you feel the brass being “smooshed” for the last 1/4” of bolt travel, stop, you found the spot.

5.) Load up rounds to these specs, effectively headspacing on the neck, dramatically increasing accuracy while reducing potential head separation and other stretching.

I’ve had guns that were 3 MOA or worse that destroyed brass on the first firing become sub-MOA tack drivers using this method.

 

[C.W. Richter]

Your last sentence, "IF you FL size, dedicate it to that one gun..." Shouldn't that read, "IF you neck size..."

You are Correct! I just read that.

 

[C.W. Richter]

*As touched upon above, I have also found that the time-saver RCBS e-powder dispenser doesn't necessarily drop a powder charge that matches its weight on a decent, old Lyman powder balance, and further, its load-to-load powder drop variability is not as precise as using the balance to measure every single powder charge. It IS a time-saver for hunting purposes, but much better are available...

 

[cmk]

Question: if I use my full length die to crimp, am I also bumping the shoulder?

I think not. It would be the seating die that has a crimp feature, but I don't think a seating die will touch the shoulder. At least, it shouldn't.

 

[RayAtkinson]

I wouldnt worry if your loads chamber easily and extract as well.. I always Full Length resize with ammo to be used hunting...neck sizing is fine on varmints and testing etc..

 

[HACT07]

Neck sizing and this thing called bumping the shoulder is what I've always done with FL dies. Not that long ago I got a set of those Lee collet neck dies and they seem to work great.

Neck sizing with a FL dies means nothing more than not allowing the die to reach and move the case shoulder. You can get any where from just a bit down on the case to almost but not quite the shoulder. You can see where the die stopped in the neck of the case. Just two or three loadings and your bolt will no longer chamber the case, it's grown to tight. At that point is where I've set my FL die for years. Trial and error and keep moving the die down and re-sizing the case until the bolt will close easily on it. Lot of guy's want to feel a bit of pressure by not taking the shoulder back quite all the way. When you have done this you have a case sized to fit the chamber of the rifle you sized it for. It may or may not fit in another chamber. Right there I lock the die in place ant it is never used except for that rifle again! I have been one to never keep two rifles in the same chambering but a couple years ago ended up with two 243's, both have their own set of dies. The cartridge's for one of them will not work in the other rifle, can't clost the bolt. Yet the cartridges in the other will fit in both chamber's.have the box's marked to keep the case's seperate.

My method of partial sizing I think is what is refereed to as bump sizing sizing. Actually you cannot bump size a case and move the shoulder without sizing the whole case the same amount. Once the case reach's the shoulder, the whole case will be touching the case. Now if the shoulder in your chamber is a bit long, the case being touched should support itself as you continue up. But if you hit the shoulder first I would think that without the case walls to support the case the case would buckle to some extent at the base of the shoulder, possibly keeping the case from chambering. The whole thing is partial sizing. The whole case is partial sized so it will fit one certain chamber. If you have not moved the shoulder enough to allow the case to be chambered, all you have done is neck size! And then the case will not fit the chamber if already fired a time or two neck sized. Whae keep's the re-sized case from chambering is the shoulder, it must be moved back some little bit to allow the case to once again be chambered. If you do not move it back the case will not chamber. If you do move it back the whole case will be resized to some degree allowing that those case's may only ever fit that rifle again without reversing to resizing per factory spec's. I rifle with excessive head space can be use without a problem by partial sizing and making the case fit the chamber.