I'm looking for help and input. I have a load that hammers right now it's all virgin brass that is about to be once fired. what's my next step to maintain the load in my once fired brass? load up 10 and check to see if I'm still in the same node and velocity. my barrel just settled in with about 170 rounds. yes I'm new and learning a shit ton about the reloading aspect.
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virgin brass to once fired load development
- Thread starter ut lead slinger
- Start date
There is no real guarantee that the same load will be equally good with 1x fired brass, but it should be close. the case capacity will change as well as pressure once you have fired it in your chamber. The only times ive seen it work out great with virgin to 1xf is with tight chambers where the brass doesn't move much. Even then it can be different some times. Your best bet is to not worry about load dev. until all your brass is fired and bumped back. Shoot the virgin brass up while shooting positional or general practice, then start your development.
Really I don’t know that it matters much. I have ran data on it every way you can. Never really came up with anything solid. I can tell you that it’s beneficial to fire your brass to your chamber that way know how far to push your shoulder back. That can help with consistency.
A lot of virgin brass parts are changing as it fire forms to your chamber. If you take detailed measurements before it's fired, like the neck tension and free bore, then you might be able to FL size to the same specs. Often, the seating resistance on virgin brass is much greater than after resizing (unless you lubed the inside of the virgin brass before seating the projectile). . . . particularly if you're doing any annealing.
Almost always you'll need slightly less powder charge in once fired brass than in virgin brass to maintain same overall performance / accuracy.
Provided you are sizing brass so there is some clearance but not overworking brass by sizing back down to virgin / nearly virgin dimensions there will be less energy required to expand brass to chamber walls, more energy used to propel bullet down barrel.
You'll need 0.1 to maybe 0.3 gr less charge in fired vs virgin. Really going to depend on how much you are sizing brass, how tight chamber is, case fill, etc.
I run 0.002" bump +/- 0.0005" bump on shoulder for AR brass.
Chronograph in fired brass with same charge as virgin, adjust charge to get same velocity and you'll most probably be done.
ok cool. barrel is a rock creek from PVA so its tight like a tiger but I have never considered waiting tell it's all once fired
Bolt gun, I tend to bump 0.001"-0.0015" +/- 0.0005"
Want slight clearance so 100 % easy chambering, nothing touching.
I usually find a solid load in virgin brass, work through 500 or so cases and then rework load for fired brass.
Exception is something like 243 AI, then I'd fireform 2-300, work up a load in FF brass. Smaller bore, faster throat erosion and less barrel life I've found that I can easily wear out barrel with 2-300 pieces of brass.
New chamber / barrel gets new brass.
OP, what is rifle chambered in?
Want slight clearance so 100 % easy chambering, nothing touching.
I usually find a solid load in virgin brass, work through 500 or so cases and then rework load for fired brass.
Exception is something like 243 AI, then I'd fireform 2-300, work up a load in FF brass. Smaller bore, faster throat erosion and less barrel life I've found that I can easily wear out barrel with 2-300 pieces of brass.
New chamber / barrel gets new brass.
OP, what is rifle chambered in?
Example. Alpha dasher brass, virgin 31.9/1xf 31.8g and the 1xf load is 30 fps faster. There is no wasted energy to blow the casing to the chamber dimensions, therefore, that energy is used in projecting the bullet
Load up 5rnds of each, in 2gr increments two steps on either side. For example if your load is 32.5gr
32.1
32.3
32.5
32.7
32.9
Fire them over a chrono and see if there is an ES node still. If it is, load in the middle of whatever it is and then if it’s not still grouping well, use seating depth to tighten it back up.
Brass prep + powder drop = powder node
Seating depth = accuracy or group node
Too many people are still using circa 1985 loading methods where they look at groups on paper with same seating depth and change powder charge based on groups.
With modern chronographs, find your powder nodes first, pick the one that’s closest to your desired speed, and then tune the bullet via seating depth (or a barrel tuner if you have one).
32.1
32.3
32.5
32.7
32.9
Fire them over a chrono and see if there is an ES node still. If it is, load in the middle of whatever it is and then if it’s not still grouping well, use seating depth to tighten it back up.
Brass prep + powder drop = powder node
Seating depth = accuracy or group node
Too many people are still using circa 1985 loading methods where they look at groups on paper with same seating depth and change powder charge based on groups.
With modern chronographs, find your powder nodes first, pick the one that’s closest to your desired speed, and then tune the bullet via seating depth (or a barrel tuner if you have one).
Oh this is just a few feet down the rabbit hole, it gets a lot more interesting the deep your willing to venture in the pursuit of perfection
Was this test on a brand new barrel with the 1x fired being shot after the virgin?
Most any new brass I run, whether it’s a new barrel or well shot, always speeds up slightly after first firing.
This thread is perfect timing...
My 28 nosler is shooting virgin Peterson brass 84gr 3010fps with 5sd and 1/4moa. Fast forward resizing. I bumped the shoulder back .002 and then reloaded to 84gr and my muzzle velocity went up to 3090 and started getting swipe marks. I’m scratching my head as I thought being fire formed I would have less pressure not more with the same amount of powder. What is causing the pressure spike? I will be backing off the powder charge to find that 3000-3010fps node.
My 28 nosler is shooting virgin Peterson brass 84gr 3010fps with 5sd and 1/4moa. Fast forward resizing. I bumped the shoulder back .002 and then reloaded to 84gr and my muzzle velocity went up to 3090 and started getting swipe marks. I’m scratching my head as I thought being fire formed I would have less pressure not more with the same amount of powder. What is causing the pressure spike? I will be backing off the powder charge to find that 3000-3010fps node.
Hard to say without more info. Was there a difference in environmental conditions? If you’re just below seeing pressure signs, it doesn’t take much to put you past it.
How far off lands are you seating?
How many rounds on barrel?
enviro was around 5-10 degrees warmer, 75-80...I’m .020 off the lands and they’re about 250 shots down the tube.
I’m using RL33 which I know isn’t the most stable
Closer brass is to chamber dimensions, less expansion of case so more energy used sooner to sharpen leading edge of the pressure curve.
You get more pressure for same charge weight since slope of pressure curve is increased.
You get more pressure for same charge weight since slope of pressure curve is increased.
