Shoulder set back 308

[alexham]

I find it difficult to throw away brass too, but you are probably overdoing the case preparation. F/L resizing is all you have to do with cases not fired in your rifle. Uniform OAL is not so important for accuracy, provided the bolt will close without forcing it and the case mouth does not come in contact with the ridge at the end of the chamber neck. The bolt will have a "springy feel" if it does and you will see bright marks on case mouths. You will find that the chamber necks can be up to .020" longer than case necks. If you use a proper neck expander button (not one on the same stem as the decapper pin) like Lyman M die, it will ensure that the neck walls that are in contact with the bullets are dead square and of the same OAL and provided you do no crimp accuracy will be 1st class. You will need to trim to length eventually, but the case may not last that long. I have reloaded one batch of 7.62X54R Sellier & Bellot cases 32 times without ever having trimmed them.

Outside neck turning pays only if you are using very poor quality brass. RWS and HPS cases are good. Yes, even the most expensive Norma cases will not have walls of absolutely uniform thickness all round, but in practice you will be hard pushed to see the difference in accuracy at 600yds or even at 1000yds.

Alex

[ovenpaa]

In the absence of a chamber drawing for your particular rifle it is worth confirming the maximum case length. I trim a case back a few mm and then stick an insert in, I can then chamber the case and insert, remove the case and measure the length. Not a very good picture but should give you an idea.

[EagerNoSkill]

I have seen several references to a "chamber cast" which I presume is some dental type plastic that is inserted into the chamber and when dried is extracted and acts as a visual and measurable representation of the true chamber
Correct Or Wrong sign85

[spud]

I have seen several references to a "chamber cast" which I presume is some dental type plastic that is inserted into the chamber and when dried is extracted and acts as a visual and measurable representation of the true chamber
Correct Or Wrong sign85

i think its callled ceracote

[dromia]

Its called Cerrosafe.

Not my recommended way of taking a good chamber cast as it changes size over time, it does come with a chart describing this. Being a low melting point metal like the stuff used in automatic fire sprinklers it is very easy to overheat if you are not care ful which can effect its properties and in extreme cases do more harm than good, ask Alpha1.

I much prefer the impact method for accurate chamber casts.

Look in our Library forum for the definitive article on taking chamber casts by Texas Mac from Cast Boolits, the impact method as wel as the pro's and cons' of the other methods are well explained.

[alexham]

Cerrosafe is an aloy with low melting temperature - under 200°F - and for best results the chamber needs to be pre-heated to the same temperature by pouring boiling water down the barrel from the breech. It is a good idea to remove action from the stock first, especially with historic/antique rifles. The cast will "shrink" as it ages, but the rate of shrikage is known and is not a problem. The cast can be remelted and re-used. I realize that this might be interesting to know, but it really has no application in jacketed bullets reloading in a modern calibre. Even if you are planning on shooting cast lead bullets and you need to measure accurately the throat of your barrel (essential for accuracy) you can do this by tapping oversize lead bullet into the rifling, from the breech; gently tapping it out and measuring over the imprint of the grooves.

Alex

[dromia]

you can do this by tapping oversize lead bullet into the rifling, from the breech; gently tapping it out and measuring over the imprint of the grooves.

Alex

Can work but not the most accurate way, see impact cast above.

[EagerNoSkill]

Thanks for advice and pointers sign92