Some more FNG .338 win questions - crimping

[Choupique]

Thanks all who helped with my sizing questions. Got to make it to the range today to try out some H4831sc. Started at the starting load, 67gr w/ 250gr grand slam at 3.355" oal and worked up to 71 grains. My 4 at 71 grains went 2663, 2713, 2708, and 2709. Accuracy was good enough to hit a 8" plate at 150 yards every shot, not much to go on but the splash marks on the target were all touching. So far, I like it more than RL17. It's less scary.

I left one round riding in the magazine till the last shot. It had 0.055" of setback by the time I was done. It basically set back to the groove, and I suspect till the powder stopped it because I couldn't hear it in there anymore, and that's basically the exact book max charge and min length, which lists as compressed. The end of the bullet was fairly mangled as well, obviously banging around in the magazine a lot.

I had crimped the hell out of them with a lee factory crimp die, which I thought would eliminate this. When I tried RL17, I had the guts crimped out of one in the groove, and it still set back past the groove, again I suspect until the powder stopped it.

Any advice? It is norma brass on it's 3rd firing, full length sized.

Side note- I think my chronograph reads fast. This load lists at 2616 from a 24" barrel. The RL17 loads were far faster than book speed, and my .30-06 garand loads were also 100fps over book speed with the same barrel length.

 

[A382DWDZQ]

I’ve seen a lot of posts saying if neck tension is good crimp is not necessary. The way you’re describing it sounds like it might be too much. It should barely be visible. If it’s too heavy of a crimp, could be getting more pressure than expected. That could account for the discrepancy in velocity and beating up the rounds in the magazine.
A couple other things that I would check are to measure the setback from the ogive, not the tip. With the accuracy, I think it is important to be as consistent as possible when shooting, and use a good target where you can see the impacts clearly. Where they are landing on the paper is good data for the load development. On the chronograph, see if you can borrow someone else’s at the range, and shoot a known good and consistent load over both, that’s really the only way you will know.

 

[Choupique]

I can crimp it too much and cause setback issues because it's not actually tight, or because it's generating more recoil and beating stuff up more? Just want to make sure I'm tracking your thoughts.

I was thinking about just seating them to the groove and roll crimping them, as I don't see how it would be possible for the bullet to push back without extreme violence. I know I have not seen this with factory rifle ammo before.

I see people post about not crimping safari stuff so it must not be totally necessary. It does seem like the bullets seat easier than they should. Maybe i still don't have my die set quite right and just don't have any neck tension?

 

[A382DWDZQ]

I can crimp it too much and cause setback issues because it's not actually tight, or because it's generating more recoil and beating stuff up more? Just want to make sure I'm tracking your thoughts.

I was thinking more recoil due to more pressure.

 

[A382DWDZQ]

Maybe i still don't have my die set quite right and just don't have any neck tension?

That is worth checking as well. Try just seating one is a sized case and then try and push it in by hand, or tapping it on the bench, and if you have a kinetic puller, see how many whacks it takes to get it out. Do that without the crimping just to see how well it is holding. You could also size a case without the expander ball and then measure the neck outer diameter compared to one sized with the expander ball in. See how much more the ball is pushing it out.

 

[Sadie]

Did you get setback without crimping?

 

[Choupique]

Did you get setback without crimping?

Yes