Hi, Everyone. This is my first time setting up a resizing die this way - I've always just followed manufacturer's instructions for full-length resizing, but now I'm trying to set it up to full-length size BUT only bump the shoulder back .002. Using a Sinclair bump gauge, my once-fired Lapua .338 LM brass is measuring between 2.203 and 2.205 (depending on how hot the test-load it came from was). The 2.205 in. brass is just slightly resistant to re-chambering, so I feel it is a good indicator of the true headspace in this rifle. I have been trying to set my Forster full-length die up to bump the shoulder back .002, which would put all my brass at 2.203 in. However, I am not getting consistent results from piece to piece. Running them through the die (all locked down as close as I can get it) I'm getting lengths that range from 2.202 to 2.204. There is no rhyme or reason to it - some pieces @ 2.204 in. or less came out the exact same length after sizing, while others got bumped back to 2.202. What gives? Is it due to brass spring-back being different from piece to piece, or something else I'm not doing? How critical is the amount of variation I'm getting going to be to precision and accuracy? I'm really striving to get 1/2 MOA out of this rifle, but the best I've gotten so far is about 0.8 in. 3-shot groups at 100 yds. I really don't need another variable screwing with me. Thanks.
- Thread starter vh20
- Start date
Re: Trouble Setting Up A Resizing Die
vh--I think you are probably right. I see variances like you describe except on brass on it's 2nd or 3rd firing or freshly annealed brass. I have not found it to be a huge factor affecting accuracy.
To find a more accurate load I find powder charge weight and especially seating depth more important and most important. I would keep checking my brass and size it minimally-as it sounds you are doing--but just keep it up and seek out those other variables to maximize your accuracy.
vh--I think you are probably right. I see variances like you describe except on brass on it's 2nd or 3rd firing or freshly annealed brass. I have not found it to be a huge factor affecting accuracy.
To find a more accurate load I find powder charge weight and especially seating depth more important and most important. I would keep checking my brass and size it minimally-as it sounds you are doing--but just keep it up and seek out those other variables to maximize your accuracy.
Re: Trouble Setting Up A Resizing Die
Do not quick stroke the press when resizing. Stroke the press to the bottom and hold it for a 4-5 second count to allow the brass to normalize in the die. Running the brass in and out without a pause in your press stroke to allow the brass to normalize will give you variations all the time.
Terry
Do not quick stroke the press when resizing. Stroke the press to the bottom and hold it for a 4-5 second count to allow the brass to normalize in the die. Running the brass in and out without a pause in your press stroke to allow the brass to normalize will give you variations all the time.
Terry
Re: Trouble Setting Up A Resizing Die
Also he is a old post I did on setting up a sizing die, with comments from many hide members. Let me state that I do you Skips die shims when loading.
Setting Up a FL sizing die
Terry
Also he is a old post I did on setting up a sizing die, with comments from many hide members. Let me state that I do you Skips die shims when loading.
Setting Up a FL sizing die
Terry
Re: Trouble Setting Up A Resizing Die
Variances in the hardness of the brass is most likely the culprit. As mentioned above, the variances you are experiencing will probably not have a material effect on accuracy. Also let the brass dwell in the die for a few seconds before lowering the ram.
Variances in the hardness of the brass is most likely the culprit. As mentioned above, the variances you are experiencing will probably not have a material effect on accuracy. Also let the brass dwell in the die for a few seconds before lowering the ram.
Re: Trouble Setting Up A Resizing Die
I tend to go slow with the ram any time I'm using a press of any kind. However, I have not been allowing for any dwell time at the bottom of the stroke beyond about one second to make sure it is fully bottomed. Allowing a few more seconds to let everything normalize is an excellent idea, and makes a lot of sense. I'll give that a try and see if it improves. Thanks!
I tend to go slow with the ram any time I'm using a press of any kind. However, I have not been allowing for any dwell time at the bottom of the stroke beyond about one second to make sure it is fully bottomed. Allowing a few more seconds to let everything normalize is an excellent idea, and makes a lot of sense. I'll give that a try and see if it improves. Thanks!
