.243WIN only groups with new Brass.

[Breeny02]

My Savage 10 .243win only groups well when loading new brass, once I reload the cases groups open up considerably.

I've tried neck sizing only, full length sizing, adjusting neck tension nothing seems to work.

Any suggestions appreciated.

 

[JohnKielly]

If you didn't prep the new brass, chances are that the neck tension was grossly tight. Try to copy that.

 

[Breeny02]

If you didn't prep the new brass, chances are that the neck tension was grossly tight. Try to copy that.

Lapua brass straight out of the box.

I have noticed that the projectiles seat much easer on the fired brass even after sonic cleaning, so could be neck tension issue.

I'll double check the neck dimensions, thanks.

 

[AJC]

Have you cronographed the two events to see if you achieved the same velocity and sd. This may give you a second data set to compare when working this problem.

 

[ratbuster]

Tagging in here

 

[mikecr]

Any suggestions appreciated.

It doesn't matter how a gun shoots with new brass, unless that's all you intend to use.
Otherwise, load develop with fully fire formed and sized as you choose brass.

 

[Texas10]

Are you annealing your necks? If so, what method are you using?

Another possibility is donuts forming in the neck. Can you slide a bullet down the unsized neck and not have it come to a stop at the neck/shoulder junction?

 

[243winxb]

Case volume changes between brand new factory brass and fired full length sized brass.
Adjust the powder charge.

If using standard dies, with expander, i have seen/measured neck wall thickness get thinner with repeated reloading. Accuracy got worse.

A Redding fl type S bushing die, with bench rest prep of brass helps also.

Last, bolt face not square to chamber? Neck sized brass should become hard to chamber after 3 or more firing.

 

[chop house]

i'm listening... saw this same thing on a mdl 12 in 22-250.

 

[Milo 2.0]

I used to have a problem duplicating new Lapua 6.5x47 brass. Neck tension was the key.
Have you chrono'd new to fired brass loads? May tell a story also.

 

[jonbearman]

Can you post a picture of a fired primer still in the case on new brass versus resized reloaded brass? What weight bullet in new brass and powder combo and do you change anything like powder weight after reloading again?

 

[AckleymanII]

try measuring the dia of new brass with a bullet seated with a micrometer, duplicate that dimension, and don't forget to take into consideration spring back when you think of bushing sizes.

 

[Dusty Stevens]

The non-round necks give the tension and the undersize brass gives the pressure. Adjust the powder charge and youll get there

 

[dgray]

I had that problem and boltface wasn’t square. Groups became larger with each firing.

 

[Bc'z]

I gotta say it....

Try neck sizing only.
Take data measurements from new brass and each firing after that.
Around 3-4 firings you'll notice tighter bolt close. Now FL size using data you have from previous firings. Bumping shoulders .002.
At this point you can send some fired brass in to have a custom die made to your chambers specs.

 

[JimSC]

I do a FL sizing and a complete case prep on new brass before the first firing, and try and do testing on fired brass using the unfired as practice rounds. makes sense to me to do the development on cases that are what the brass is going to look like on the 2nd, 5th etc firing.

have you tried tweaking the charge weight or primer on the once fired?

 

[Yote Hunter]

I had a friend that shot a Savage 25/06 at 1000 yards and he noticed virgin brass shot much better also. After firing the casings he tried to neck size the brass and groups were considerably worse at 1000 yards. Someone at the Ohio 1000 yard range told him to full length size his casings because his chamber probably wasn’t square with his bolt face also. Sure enough once he done a good full length resize on his casings accuracy returned. He went on to hold the factory gun range record for several years after that. Around 4 1/2” for 5 shots.

 

[Homerange]

It doesn't matter how a gun shoots with new brass, unless that's all you intend to use.
Otherwise, load develop with fully fire formed and sized as you choose brass.

This ^.
Breeny02 as a newbie has been short on info, no charge weight or powder or bullet type.
Who's to know where he's at or even how much experience reloading he has.

We are not mind readers, give us something meaningful to work with please.


A further comment on the 243 Win, it is a relatively modern cartridge loaded to high pressures so trying to reinvent the wheel when working with it can produce unpredictable results. Get a few reloading manuals and/or use the powder manufacturers online data and study it. Crony loads to see how close you are to the edge where listed data stops, why because they have the gear to know when loads are unsafe and unpredictable so only list loads that are known to produce acceptable results.

From one of my bibles; Cartridges of the World:
Editors note: The 243 has garnered a reputation among ballisticians for erratic performance. Handloaders should keep this firmly in mind.

Disclaimer
I load for my sons 243 and it shoots reasonably well, however we don't push it or our luck.

 

[Fliers]

Perhaps your expander ball is inducing a lot of run-out on the neck.

 

[dolek]

Perhaps your expander ball is inducing a lot of run-out on the neck.

From the OP...I've tried neck sizing only, full length sizing, adjusting neck tension nothing seems to work.