Anyone Partial Length Sizing a 243 or 7mm-08?

[beartooth91]

I made a similar post last week regarding questions I have about PL sizing. Still don't know what I'm doing, but, here's some data. I have a .243 and a 7mm-08, both in Savage short actions. I have now fired all my new brass and would like to PL size.
Today, I took a bunch of my .243 brass, a Sharpie, and backed off the Hornady die up to 1 full turn. Note that the unsized, once-fired brass chambers easily. At 1 turn backed off, there's a slight ring at the shoulder and the bottom part of the neck is untouched. I have some chambering resistance at this point. As I work the die in, a 16th, at a time, I see more and more of the neck get sized. Still have chambering resistance. Around 1/8th of a turn, backed off, I begin to see some colored lube along the shoulder. the neck looks to have a very thin ring of ink-oil at its base. Chambering is noticeably easier at this point.
With my inexperience; it **seems** that 1/8th of turn backed off isn't PL sizing, but, with this case I'm not sure what others are seeing. Note these are New Dimension dies and the instructions say to screw them down until they just touch the shell holder at the top position, without camming over, for full length sizing (ie. no additional turns in).
Are any of you PL sizing a 243, 7mm-08, or .308? If so, how far backed off are you? Can doing this (wrong) lead to excessive head space ? Or should I just forgo it and buy the Lee Collet dies?

Thanks,

Mark

 

[Zak Smith]

Backing off the dies can result in inconsistent resizing as things flex. A much better solution is to use the Redding Competition Shellholder sets which have +0.002, 4, 6, 8, and 10 inch shell-holders (ie to increase the "headspace" that much). I have used these extensively in .338 LM and .260REM and they work great.

 

[243winxb]

243win

If so, how far backed off are you?

.004" between FL die & shell holder.

 

[Ol` Joe]

The resistance you`re feeling is probably the shoulder being moved forward by the expander ball, although the brass from expanding the case walls will move the shoulder foreward some too. Brass with striaght walls like the 308 family are not good canadates for partial sizing. The tapered brass like the `06 or old 7x57 where there is no contact with the case except for the neck work much better.
Try to part sizing a case with out the expander then re size again with the expander back in the die to open the mouth and decap the case. Sometimes the expander going in doesn`t move the shoulder like pulling it back out does. See if it helps stop the resistance for you. Don`t forget to lube the mouths slightly.
BTW I`d bet if you have a run-out gage you`ll see much less run-out on brass sized this way then the regular way with the expander in place to start.

 

[Zak Smith]

Brass with striaght walls like the 308 family

.308 Winchester is tapered.

 

[MCMXI]

A much better solution is to use the Redding Competition Shellholder sets which have +0.002, 4, 6, 8, and 10 inch shell-holders (ie to increase the "headspace" that much).

I use Redding Competition Shellholder sets for all of my rifle cartridges too. I load for four different .308 Win rifles, one bolt and three semi-autos, so they're particularly useful in that I don't need to adjust the Redding body die at all when sizing cases for any of the rifles. As Zak stated, the Redding CSHs decrease the amount of shoulder setback on the case by the amount stamped on the shellholder when compared to standard shellholders from RCBS, Redding etc. For example, if your die and standard shell holder are set up such that the resizing process results in a case "headspace" measurement of SAAMI - 0.006", if you now install the 0.006" shellholder and size another case, it should be right at SAAMI + 0.000".

 

[243winxb]

Read this >

http://www.brownells.com/.aspx/lid=...g_Success___Minimum_Headspace_and_Maximum_COL

Some brass on firing will get shorter, not giving a true head to shoulder measurement.

 

[GP100man]

I bump the shoulder just enuff to allow good bolt closure !

On a HB 7-08 it liked the bullet touchin the lands & the brass tite , had to cam the bolt closed on it .

As you fire the brass more you will probably have to go down with the die to get a small bit of body sizin with the neck sizing.

My 7-08 liked formed brass from remington 308.

 

[Ol` Joe]

.308 Winchester is tapered.

Zak all brass has some taper I should have said straight(er). Even stuff like the 9mm or 45/70 has a bit of slope.
I still stand on my assessment of Partial Sizing 308, 223 or other "straighter" body walled brass, it doesn`t work as well as PS more tapered cases. If you smoke a 308 case and run it in a FL die you`ll find it starts to size the body as well as the neck, tapered brass like the ones mentioned allow more of the neck to be sized before the die acts on the body. Squeezing the body walls can cause shoulders to move forward and the result is stiff chambering unless it is bumped back. Bumping the shoulder back negates the whole idea of partial sizing IMO.