I've shot two different manufacturers ammo out of my custom 260 Rem and had no problem. I just started reloading and got some Lapua brass and loaded a bunch up. Went to the range and they wouldn't chamber. At first I thought I seated the bullets too far out. Eventually, I figured out it was the thickness of the case necks. I trimmed the necks and they now 'fit'. I hope I didn't trim them too much but I tried to get to the same outer loaded round case neck dimension as one factory loaded round I had that fit fine. (BTW, I have a Forster hand trimmer that I used for the first time and the mandrel was very tight and difficult to get started which I didn't like). However, I don't won't to have to trim down Lapua case necks all the time. I don't know if I have a tight chamber since the factory ammo cycled just fine. Am new to reloading and I am amazed how some things can apparently come down to a couple of thousandths in dimensions. I now have a bunch of bullets I have to pull and reload. Any other brass I need to worry about before I get some new brass to avoid having to trim necks?
Lapua case necks too thick for my rifle
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Did you trim or turn the necks?
lancetkenyon
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As Eric H asked, trimmed? Or turned? Sounds like you "turned" them if it was a diameter problem.
If virgin brass didn't fit regardless of brand, I assume your custom .260 Rem has a non-SAAMI chamber. Like a tight neck/match chamber with minimum dimensions.
If virgin brass didn't fit regardless of brand, I assume your custom .260 Rem has a non-SAAMI chamber. Like a tight neck/match chamber with minimum dimensions.
Yes, turned them because of a diameter problem. I am guessing then that the there is likely enough variation in loaded brass that some brands will fit and others won't in a tight/match chamber with minimum dimensions. I guess I got lucky using some Federal and Barnes loaded ammunition that seemed to fit fine.
If it's a custom the smith should know which reamer he used. A saami reamer would not have issues. This is also something you should discuss with the smith. If it's a second hand gun the seller should have let you know it was a tight neck chamber.
lancetkenyon
Well-Known Member
Yes, brass has variations between manufacturers. Lapua usually has .015" necks. But Lapua and Alpha are the top two brass for the .260Rem.
Do you know if Lapua .284 cal necks are thinner than 30 cal? I sized some 308 into 708 and they needed turning to have clearance. I'm wondering if I go Lapua 708 if they be thinner.
Also, does anyone know what case holder I can use with my primered cases to trim them? I have the Forster which I could use, but it is not a very good design and slips too much and holds the case at different angles as it slips. Some of the holders appear to use the primer pocket to help keep things tight, which I of coarse can't if I want to use my loaded cases.
lancetkenyon
Well-Known Member
When you neck down, you are taking all the brass that is in a .308 neck, and forcing it down to .284. Meaning the brass slightly thickens as it has to go somewhere.
The only reason I can see going from .308 Win and necking down when 7-08 brass is available is if you use the .308 Win Palma cases for the SRP. Or you got the .308 brass for free.
lancetkenyon
Well-Known Member
Loaded cases? Or primed cases?
I don't know of any neck turning tools that can do it with a loaded case. You have to have a turning mandrel in the neck. Unless maybe you use a lathe with a chuck to hold the case head.
I know all that. What I must have dilly danced about was, does Lapua make .284 brass thinner than 30 cal brass?
I have primed cases (no powder/seated bullets) and loaded cases (with primers and powder, the ones I found out wouldn't fit in my rifle's chamber, and those I will pull the bullets, dump the powder, but the primer will still be there of course and will need to turn them to be able to use them).
That was hard to follow, but yes, you can turn necks with a primer inserted.
