Total newb question: undersized brass?

[BigJ]

Regarding .223:

Lets say I've figured out a load I'm happy with. Lets say that load shoots 2MOA out a particular rifle, with brass in length anywhere from 1.75 to 1.755".

Now lets say I come by a batch of LC surplus once fired brass. Spot checking it tells me its well under sized; lets keep it simple and say it checks in at 1.735".

Here's my question: should I reset my seating die to ensure my bullet is seating at the same depth within the case, with the shorter brass? Or, instead, am I good to go to leave things as they are since its the overall length of the completed cartridge that matters more; where the bullet sits (in this example) just wont matter enough to worry about (aka it will still shoot 2MOA with the shorter brass)?

Thanks guys

[joelogic]

Its length is shorter, its not undersized.

Any change affects your load. Crimp consistency will change. However 0.02 is hardly anything. YMMV. Use Caution. BLAH BLAH BLAH.

This is the reason I trim to 1.735" because it is typically the shortest of any fired .223 brass.

[BigJ]

Shorter, not undersized. 10-4.

Trimming everything to 1.735" then formulating the load just makes darn good sense. Hadn't thought of that.

[mark501w]

Oal is unaffected by case length.

[BigJ]

Oal is unaffected by case length.

Agreed. But where the bullet sits in the case (and therefore where the crimp on the bullet), is. No?

[milotrain]

No, just length of case neck engagement. The bullet is seated based on a distance from the shell plate to the seater die stem, it doesn't care about the case at all. I know a guy who shoots brass that is cut super short, shoots just fine.

[mark501w]

Yup I don't crimp box magazine ammo I crimp tube mag ammo.

[Witch Hunter]

Unless you crimp into a cannelure, there should not be any problem. For accuracy, who knows? There is a small amount of neck tension difference by having less bullet in the neck. In a 2 MOA rifle, it might not be perceptible.