Questions. Bumping shoulders back.

[Alpha1]

Setting the shoulder back on my cases is something new to me. I have invested in body dies competition shell holders and have found some quite novel ways to carry out and measure shoulder set back on the net. I am quite surprised by the amount you can actually set them back. I have not re loaded any of the cases I'm still on a learning curve. I did wonder though is it possible to set them back to far. If so what would be the consequences. Are there any signs that indicate you have gone to far.

[phaedra1106]

The most obvious problems would be increased head space within the chamber and a reduced case capacity, either could cause excessive pressures on their own but together could easily be a recipe for a major disaster.

Measuring the amount of "bumpage" is fine but you really need to go by what works for your particular rifles chamber.

You should be aiming for a head space of around 1 to 2thou", easy enough to check using a piece of shim stock fitted between the case and the bolt face, if the bolt closes easily on 3thou" then you need to reduce the amount you're bumping the shoulder back. If you're using a standard shell holder then you can simply back out the FLS die a small amount and re-size another case and check that, keep doing this until the bolt is stiff to close at 2thou" and you will be close enough.

[WelshShooter]

Buy one of Ovenpaa's case length gauges. That measures the case from the Base to datum on the neck. You can measure shoulder bump that way.

[Alpha1]

I have shoulder bump measuring gauges measuring is not a problem.

[WelshShooter]

Sorry Alpha, just re-read your first post (perhaps I shouldn't post so early in the morning?). As phaedra has pointed out, shoulder bumping is typically 0.001" to 0.002" from case formed brass. I'm not sure how you are controlling shoulder bump but I do mine using the full length sizing die. If you are using a full length sizing die to achieve this, then the most you can bump the shoulder back to is to SAAMI specification for the case because you adjust the full length sizing to until it contacts the shell holder so it's impossible to bump the shoulders back any further using this method.

[phaedra1106]

He has a set of the Redding stepped shell holders, http://www.redding-reloading.com/online ... older-sets

These have their bases raised in 2thou" steps, the other ways you can do it easily are to mill off say 5thou" from the bottom of a FLS die and adjust it down slowly as I mentioned above or RCBS do "Small Base" dies usually used for auto or belt fed rounds, these size to the minimum Saami spec to ensure consistent feeding.

[Alpha1]

I bought some New Lapua brass. I'm using one of the new unsized cases as my base line. I full lentgh sized a case fired in the rifle with a normal die set up. The shoulders on the resized brass are set back further than the new Lapua brass. That surprised me the set back is quite noticeable.

[The Gun Pimp]

Alpha! - as we've said before - YOUR chamber is the guide.

With firing-pin assembly removed, size your fired brass so that the bolt JUST kisses it on closing.

Dimensions are irrelevant - your chamber is what it is.

[WelshShooter]

He has a set of the Redding stepped shell holders, http://www.redding-reloading.com/online ... older-sets

These have their bases raised in 2thou" steps, the other ways you can do it easily are to mill off say 5thou" from the bottom of a FLS die and adjust it down slowly as I mentioned above or RCBS do "Small Base" dies usually used for auto or belt fed rounds, these size to the minimum Saami spec to ensure consistent feeding.

Ah, in that case Alpha should disregard my post above. Obviously if you're using stepped shellholders you can bump the shoulders back farther!

[Alpha1]

Yes my chamber is my guide. I'm aware of that my question is can you bump them back to far and if so what are the consequences.