Once fired brass case prep

[Tony1320]

Would you run once fired Lapua Palma brass through a Giraud trimmer for consistency or wait until it grows to trim length?

I've read some trim every firing and some like it long near chamber length so carbon doesn't build up.

 

[retired]

measure your chamber neck length and trim for it no some generic spec.
sinclair makes a tool to measure neck length.

 

[spife7980]

I trim every time because I have a giraud and its just too damn easy to not use my investment. IF the measurement is X.xxx-.020 Ill trim it to the X.xxx-.010, I put them right in the middle of the "no some generic spec" again, because its just too easy to not blow my face off and theres really no appreciable reason to not trim when your machine takes so little time to use.

 

[NorCalMikie]

If you use "bushing bump dies", the case OAL won't grow like a full length die does. And the only way you would blow your face off with a case that is .020 shorter than the chamber is if you did something stupid! (like load the hell out of it)
And if you're that concerned about blowing your face off, you better take up basket weaving and leave the gun thing to someone else.

 

[L W P]

Knowing your actual chamber neck length, what would be a safe place to stop and trim the necks? .000" to .020" from max length or what number? I'm sure .000" isn't safe but I just used it for comparison.

 

[Dusty Stevens]

Knowing your actual chamber neck length, what would be a safe place to stop and trim the necks? .000" to .020" from max length or what number? I'm sure .000" isn't safe but I just used it for comparison.

.010 shorter than trim length or match the shortest if its not more than .005 shorter. Then trim again when they get to .005 from trim length again.

 

[L W P]

.010 shorter than trim length or match the shortest if its not more than .005 shorter. Then trim again when they get to .005 from trim length again.

So your saying that if my actual chamber neck length is x.xxx. And using that as my max length I should then trim .010" off?

 

[Dusty Stevens]

Yes. If the max case length is 2.000 there will be or should be a trim length of 1.990. Trim them to that and dont touch them again til they measure 1.995 then trim back to 1.990

 

[L W P]

Yes. If the max case length is 2.000 there will be or should be a trim length of 1.990. Trim them to that and dont touch them again til they measure 1.995 then trim back to 1.990

Ok, I wasn't sure how close to the end of the chamber neck length the brass could go. So if I keep the brass trimmed .005"-.010" from the chamber neck length I should be safe. Wasn't sure how much of a buffer gap was needed before the brass touched the end of the chamber neck.

 

[Dusty Stevens]

Ok, I wasn't sure how close to the end of the chamber neck length the brass could go. So if I keep the brass trimmed .005"-.010" from the chamber neck length I should be safe. Wasn't sure how much of a buffer gap was needed before the brass touched the end of the chamber neck.

Yes .005-.010 is sop. If you shoot quite a few short ones then go long you could have a problem with carbon crimping your case mouths causing pressure issues

 

[L W P]

Yes .005-.010 is sop. If you shoot quite a few short ones then go long you could have a problem with carbon crimping your case mouths causing pressure issues

Ok, thank you sir.

 

[NorCalMikie]

Remember, it's the "actual" measured length of your chamber you're looking for. Get the measuring plugs, measure that chamber length, write it down and refer to it before you even think you need to trim that brass. You may be surprised at how often you DON'T need to trim.
And as mentioned, firing short brass a bunch can cause carbon build up just ahead of the case neck so keep that in mind too.

 

[Rsadams]

The best way to avoid carbon or copper is to not let it build up in the first place...

 

[L W P]

The best way to avoid carbon or copper is to not let it build up in the first place...

Good advice

 

[Bart B.]

If you can repeatability discern a .010" spread in case length impacting accuracy, trim every time. There are bigger fish to fry.

Find a way to test so you don't know which case length you're testing. That keeps your opinions and assumptions out of the system.

 

[dmoran]

If you can repeatability discern a .010" spread in case length impacting accuracy, trim every time. There are bigger fish to fry.

Find a way to test so you don't know which case length you're testing. That keeps your opinions and assumptions out of the system.

What way of testing it have you used?
What were your results?
What all aspects are the "bigger fish to fry"?

 

[Bart B.]

What way of testing it have you used?
Shooting several thousand rounds of ammo with .010" spread in case length at ranges from 200 to 1000 yards. Calculated the probable spread in bullet pull force with a .010" difference in case neck grip length on bullets. Not enough to fix.
What were your results?
No discernable difference in accuracy.

What all aspects are the "bigger fish to fry"?
Everything else relating to accuracy or precision of where bullets land down range based on my priorities. Case lengths at the bottom on my list. Others can have different priorities.

 

[dmoran]

Shooting several hundred rounds of ammo with .010" spread in case lengt at ranges from 600 to 1000 yards

No discernable difference in accuracy.

What average accuracy level was achieved?

Everything else relating to accuracy or precision of where bullets land down range based on my priorities.

The topic and OP's question is "once fired brass prep".
What all aspects are the "bigger fish to fry" that pertain to the topic (brass prep)?

 

[Bart B.]

What average accuracy level was achieved?

Ammo tests were 1/4 to 1/3 MOA at shorter ranges, 1/2 to 2/3 at longer ranges.


The topic and OP's question is "once fired brass prep".
What all aspects are the "bigger fish to fry" that pertain to the topic (brass prep)?

As I don't think a lot of brass prep is necessary, sorting them to 1 grain weight spreads is enough.

 

[dmoran]

Ammo tests were 1/4 to 1/3 MOA at shorter ranges, 1/2 to 2/3 at longer ranges..

To get this straight, you said in your post #17, test results from 600 & 1000 yards.
With that and your last post, I take it your saying 1/4 to 1/3-MOA at 600yds and 1/2 to 2/3-MOA at 1000yds.
Is this correct?

Also, expand on what rifle and setup was these case length tests shot with?