Question on brass prep, please help

[Bassnbow]

Have you measured chamber end length to know what YOUR max is?
Are you getting shiny spots on ejected case mouths?

I haven't, but I have bore scope and will check with brass in chamber,. No shiny spots

 

[Bassnbow]

No way the brass is stable after a single firing, don't bother trimming until it is.

What die are you sizing the cases with? I'd be much more concerned with making sure you don't oversize the not fully formed cases than trim length.

Run a borescope down from the crown on an empty case closed in the chamber and look at what you've got, $5 you're still short, will be short even after the brass stabilizes, and will only need to trim to uniform the length once you really start bumping shoulders consistently. The 40* shoulder comes with a significant benefit over the old 17.5* degree shoulder.

I do have a bore scope and will check, thanks. I'm using Redding comp dies with rod removed. Neck size with Sinclair mandrel. Also have Redding comp shell holders, so I can be sure to only bump shoulder back .002.

 

[Bassnbow]

You need 3X firings on Peterson brass before you will see and consistency, don't trim and don't do any serious load development until then

thank you, that is what I needed to know

 

[nwmnbowhunter]

Please give your full load data.

Bullet and weight
Primer
Charge weight
Overall length
Fps

Your pressure signs and speed tell me you are over charging.

Changing from soft to hard brass is very unpredictable.

I think you need to start over with minimum charges and do a ladder/ pressure test to find your safe maximum charge. I stop at ejector marks.

And just fyi. Going from virgin to one time fired brass will change again and you'll have to find your node again by dropping a few grains and working back up.

 

[skipglo]

Trim to Book COAL!

 

[HVGBDT]

Have you tried these for overall case length? I have hardly ever trimmed length on cases.

 

[QuietTexan]

I do have a bore scope and will check, thanks. I'm using Redding comp dies with rod removed. Neck size with Sinclair mandrel. Also have Redding comp shell holders, so I can be sure to only bump shoulder back .002.

The trick is you want to be sure to only bump them back after they're fully sized. If you bump back 0.002" after the first firing you're actually oversizing the cases.

At some point in this very good discussion of shoulder setback he specifically mentions chambering the fired brass to determine if the brass has actually grown to full size before bumping shoulders, I wish I had taken notes on exactly what time he mentions it, I think it's in the Q&A starting around 45 mins maybe.



This is his video regarding setting up a die specifically, 4:00 he talks about jamming the lands to fireform shoulder fully:

 

[Mike Matteson]

I will go along with most of what's been said above. It doesn't work if you cutting your neck for thickness. It's better to cutter your neck thickness on virgin brass before working them over. The first step would then, you would have to set your case over all length to be consist to cut for thickness, and stop at the start of the shoulder, and not go over or under cuts. I am set up to place my brass into a case length cutter every time to be sure there case consistency. What I have found so far that Peterson brass COAL is short of what called out in the reloading manuals. So case length shouldn't be problem if Peterson brass is consistence of being short then there not a problem. You do need to check your case lengths all the time.

 

[Reelamin]

I don't do anything posted other then measure off the shoulder and just use a bullet diameter insert that fits over the neck. I cannot remember the last piece of bolt action rifle brass I ever trimmed for length. Been reloading for 45 years and won't use a gun that shoots over .75" and my goal is .5" or better. I have only loaded for two custom guns the rest are factory as in Remington Ruger savage basic models not what many call $3000 "Factory" rifles.

 

[Mikecr]

I don't trim cases for neck turning. Just touch the neck-shoulder junction by eye, and just to mitigate donuts.
First off I measure chamber end length with a gizzy Sinclair sells for this. I do not care for necks being the same length as much as I care about chamber end clearance. Here I want to be within 10thou, eventually trimmed to 5thou short of chamber end (if ever trimmed).
It helps to stay away from cartridges with less than 30deg shoulders, or to heavily FL size any cases. Makes this matter easier for sure.

 

[Bassnbow]

I will go along with most of what's been said above. It doesn't work if you cutting your neck for thickness. It's better to cutter your neck thickness on virgin brass before working them over. The first step would then, you would have to set your case over all length to be consist to cut for thickness, and stop at the start of the shoulder, and not go over or under cuts. I am set up to place my brass into a case length cutter every time to be sure there case consistency. What I have found so far that Peterson brass COAL is short of what called out in the reloading manuals. So case length shouldn't be problem if Peterson brass is consistence of being short then there not a problem. You do need to check your case lengths all the time.

Thanks to all for your replies and the attached video. I do have all the tools to follow the videos steps and am planning on doing so. I see many of you recommend not trimming at all until brass is fully fire formed, which certainly makes sense, but I guess I assumed the different length necks would have an negative impact on accuracy. I guess i was hoping to shortcut the process to save components and barrel life, but like most things I guess you can't shortcut if you want it RIGHT.

 

[QuietTexan]

Nah you're all good, bass trim length is way less important than setting the shoulders and necks correctly. You should see great accuracy without trimming with all the other work you're doing. Stabilizing shoulders is something not everyone is patient enough to do.

 

[Bassnbow]

Nah you're all good, bass trim length is way less important than setting the shoulders and necks correctly. You should see great accuracy without trimming with all the other work you're doing. Stabilizing shoulders is something not everyone is patient enough to do.

Thank you, that is the route I will take

 

[jthor93]

Depending on how close the brass is to your chambers headspace, it may take 1 or two firings, sometimes more to fireform your brass. That being said, do the following to see if your brass is fire formed to your chamber.

After your brass is through its first firing, take your firing pin and ejector plunger out of your bolt. Then take your fired brass and see if your bolt closes on it without effort. IF there is resistance, your brass will need a shoulder bump. Take a Short Action Customs headspace comparator with the correct comparator or the Hornady one and get your headspace measurement. Then go through your resizing routine: decapping, cleaning, annealing, lube, and then resize a piece of brass with a .002" shoulder bump, use your comparator, and see if it chambers with your stripped bolt without resistance. If it does, your golden, if not, give it another .001" until the brass chambers without resistance and then resize all of your brass.

Note: If your fired brass chambers without resistance, set up your FL sizing die to size without bumping the shoulder at all, it still needs more firings to form to your chamber.

After sizing your should trim, chamfer and deburr every time for consistency. Peterson Brass is in the same league as Lapua and Alpha OCD brass.

The only prep i'll do with virgin premium brass is expanding the necks with an expander mandrel and a trim, chamfer and deburr. I have the Henderson Precision gen 2 tri-trim so that's only one operation for me. Disclaimer: I order 300-500 cases for my competition rifles and 200 for my hunting rifles. Once I hit 100 rounds in my barrel, i'll start load dev finding my velocity and seating depth node.