Fully length resize 308

[Top Hunter]

Hi Guys been a little while since I was on but now have a question.
I have started reloading 308 to get better accuracy, been loading 223 neck sizing for many years.
My question is, I see a lot about 'bumping the shoulder' of once fired cases, using a FL die.
How do you bump the shoulder using this die, wont it full length resize it anyway if you set the die to touch the shell holder ? The videos on YT show increasing the die down to 'bump' the shoulder back more, how can this be ? If it's already been full length resized.
I check the headspace using a Lyman headspace gauge and the are mainly ok, I might just have to give the odd one a extra'nip' to make it right, they always fit in the breach and extract with out any sticky bolt issues. I hope this makes sense I am just a little confused about shoulder bumping and full length resizing. Look forward to a response PM is fine.

[The Gun Pimp]

You might like to read the 'shoulder bumping' thread from Alpha1 - he's been going through the same exercise.

[bradaz11]

there are a few from him on this subject to choose from. some of them contain excellent info. I think the earlier ones contain the best info

[Alpha1]

Yes I did wander off topic a bit in the shoulder bump thread. Im off out now when I come back I will add to the shoulder bump thread and describe a simple way to bump .308 cases shoulders back using a full length die. All you will need is a decent set of calipers.

[phaedra1106]

99.9999999% of rifles will chamber a case that has been Full Length Sized (that's the point of things like the SAAMI specifications).

You may get a rifle with a chamber that was cut when the reamer was at the end of it's life or it may just be right on the minimum specification, I had a Howa 308 like that, cases full length sized by Lee, Hornady and RCBS dies would not chamber without a fair amount of force on the bolt. There are various methods to bump the case shoulder back, you can get RCBS small base dies, Redding competition shell holders which go up in height (compared to a normal one) and thus push the case further into the die or have someone skim off 5 thou" from the bottom of your die and gradually screw it down until a sized case will chamber.

Setting minimum headspace is a different kettle of fish, normally a standard FLS die with allow a sized case to fit in virtually any chamber, there are tolerances on both the case size, the chamber size and differences between difeerent manufacturers dies etc. etc. In order to minimise the amount of stretching a case does when fired, as it expands to fit YOUR chamber it's fairly easy to reduce this amount of expansion by creating a minimum amount of headspace, the difference between your case and the chamber which it expands into, the easiest way to do this is by reducing the amount the case shoulder is bumped back by the die.

Simple way, set you FLS die as per manufacturers instructions, then do the following (for a basic min bump amount)

Using a case (or several) that have been fired in your rifle,

1. Unscrew your die 1 complete turn, re-lock in place
2. FLS a fired case, try it for fit in your rifle, case only, no bullet needed. If the bolt closes without any undue pressure back the die out a further 1/2 turn (unlikely)
3. If the bolt either won't close or takes lots of force, unlock and screw the die 1/8 of a turn back in, lock and repeat 2.

Repeat 3. then 2. as required until the bolt closes with normal force (test it with no case in to compare)

Just to be certain take another couple of previously fired cases and run them through the die with the new setting, make sure the bolt closes OK.

If you want to measure the exact amount of bump you'll need to invest in some nice shiny expensive measuring toys :)

I managed to get some 1 and 2 thou" shim stock punched out into 11mm dia. disks. Fitting them in between the bottom of the case and the bolt, with a 1 thou" the bolt closes normally, with a 2 thou" there's just a small noticeable amount of resistance, with both (3 thou") it won't close without taking a huge whacking mallet to it!. This (to my mind) suggests I have a sufficient amount of shoulder bump to give me approx: 2 thou" headspace.

Hope that makes some sense :)

I need a drink now

[Alpha1]

The previous post about covers it. The simplest way to measure shoulder bump is to use a shell holder as a measuring tool. Set your case down on a flat surface select a shell holder that will sit on top of your case and rest on the shoulder. Then take your calipers and measure from the bottom of your case to the top of the shell holder. Basic but it works. Of course if you are really serious and want the best tool for the job the shooting sheds is worth a look.

[Duey]

you may find with 308 cases that they will not show any tightness on closing the bolt for a good few firings
I neck size generally and only need to bump the shoulders back after about 4 to 6 firings
however it can be good practice to use the FL dies to bump back the required 2tho after each firing and possibly actually totally FL sizing after every 8 firings as you may find the area above the head/rim of the case starts to grow a little if not kept in check, this all depends on how hot/mild you load as to how often you do each process

Duey

[phaedra1106]

My 3 centrefire (6.5 Creedmoor, 260 Remington and 308 Winchester) dies have all been set at 2 thou" and the fired cases now require very little effort to full length size.

Certainly helps when you have 200+ cases to size and arthritis :)

[Top Hunter]

Thanks for the replies guys, it's getting clearer now, I tried a once fired case in the gun this afternoon, it was a little tight, so I put it into thr FL die set as Redding says, touching the shell holder, gave it a nip on the press, it then fitted perfect, job done ? Or not ? Tell me if I am right.
P

[The Gun Pimp]

Job done!