Neck size and trim new brass?

[JWCalgary]

Noticed yesterday at the range that one of my lapua reloads was tight to chamber unlike all others I have reloaded so far.

Do you neck size and trim your new brass .... not fired yet. I figure it may be good practice but practically speaking may be a lot of work.

Thoughts?

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[elkhunter11]

I run all new cases through a neck die to remove any dings, but I do not trim, as they are always well below the maximum overall length.

[Pathfinder76]

When it comes to initial case preparation I’m a firm believer that full length resizing is something that should be avoided. I know guys that do it, which is fine, but I do not and feel that it should not be a part of the initial stages of new brass prep. Make sure right off the hop that it is not a COAL issue. If your COAL is not excessive it might be the brass. There are some instances where new brass does have a crush fit, but they are relatively rare. I am a bit surprised that is happening with Lapua brass, but it could happen. Another issue is excessive case length but I have never seen that in a new case ever. But I’m sure it could happen. If it is the case neck, a more likely scenario is a burr at the case mouth. That can cause issues with chambering and I have seen that.

There are three issues that can result from resizing new brass. One is concentricity (good and bad), two is headspace issues (more common than you think) and three is unnecessarily work hardening your brass. Unless you have the tools to measure these two things, avoid the practice. I’m also a bit stumped as to why people believe that their $30 FL resizing die is somehow superior to what Lapua might have in their factory.

Trimming new cases is not a horrible idea. Some batches of brass vary so much in length that I have, in the past, trimmed all brass to match the shortest OAL. Consistent bullet release is key to accuracy. Neck tension matters, and neck length affects neck tension. Again, not something I would consider an issue with Lapua brass.

My initial case prep goes as follows:

I lube the inside of the case necks with Hornady One Shot on a Q-Tip and let them dry. I have used graphite but I have experience galling and don’t use it any more. Then I run all of them over a Sinclair neck turning mandrel. The neck turning mandrels are two thousands under bullet diameter and I personal prefer that to the one thousandths of the neck expander mandrel (all my mandrels are chucked in a drill and polished with JB or Iosso bore paste). After expanding the neck I brush the inside of the neck with a bronze bore brush and then chamfer and de-burr the case mouths. Then I prime, add powder, and bullets.

If you are experiencing crush fit with the odd case, know that pulling the trigger fixes that problem going forward. Don’t fret about it too much.

[Smokinyotes]

Nosler brass I just load and shoot, trim to min length after fire forming. Lapua brass I neck size and chamfer prior to firing.

[JWCalgary]

I think I figured out part of the issue. I will try the above as well but I am loading to 2.9 (308) which is long-ish. However I am loading from the tip of the nosler AB not the ogive. Think it may be tension on the bullet contacting the rifling causing the heavier bolt close. Going to pick up a comparator this week to see if I can get the groups a little tighter and solve another piece of the puzzle.

So far it's looking pretty good but I know the girl can do better. The below is 200 m at Milo.


The Super green / yellow target is from the Sauer 300wm with factory hornady 180gn at 300m. Just posting that one cuz I'm pretty happy with the results.

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[260 Rem]

While you are waiting for the comparator you could give this a try. Use a thin cut disk on your dremel to cut a slit on each side of the case neck. Not bad idea to drill out the primer pocket so you can insert a rod to push out a bullet if it gets too tight. That shouldn’t happen, but if it does, the bullet can easily be pushed out without plier marks.
Insert the bullet with the top 1/4 of the bearing surface in the split neck and chamber the round. Slowly eject. Measure. Repeat several times to make sure you are getting (close to) consistent measurements. This “technique” usually gives a pretty good indication of where the lands are.
A bonus is that you can use the same split neck case to set up your seating die.
And, you get a visual of where the bearing surface of the bullet is sitting in relation to to the neck-shoulder junction where an accuracy killing donut can form.