bullet got pushed into brass case too deep

[7x57]

But I am wondering if that round would have been safe to shoot?

No!!! Pressures will be higher, as there is less initial volume to expand into. You have no way of knowing just how much higher, either. I gather this is a particular problem with .40 S&W, being already relatively high pressure, and Glocks, as they do not fully support the case head. Apparently this has led to quite a few Glock ka-booms with officers who carry Glocks in .40 and make a habit of chambering and ejecting the same round over and over as they go on and off duty. But that doesn't mean it's a good idea with any cartridge or pistol, just that your margin of safety seems to be particularly slim with that particular combo.

.45 ACP is relatively low-pressure and large volume, but never the less I rotate rounds and watch for visible setback in my 1911 (another model that tends not to fully support the case head) all the same.

7x57

[ar15barrels]

No!!! Pressures will be higher, as there is less initial volume to expand into. You have no way of knowing just how much higher, either.

If you modeled the initial load in quickload and then changed the seating depth in QL, you would have a pretty good idea.

[J-cat]

Are you sure that's true?

I always thought that a crimp works by either:

• forcing the top edge of the case slightly into a cannelure on the bullet (for rifle rounds), or
• rolling the top edge of the case into a bullet without a cannelure (for pistol)

And the purpose of a crimp is to increase tension between case and bullet, mostly to prevent bullet setback during feeding (from a magazine), but also to increase bullet starting pressure, which gives you a more complete and consistent powder burn.

A roll crimp creates a mechanical lock on the bullet by rolling the case mouth into a crimp groove. It increases bullet pull, but not by increasing case tension. The bullet now has to overcome this lock in addition to the friction exerted on it by the case walls.

Case tension is the degree of friction exerted by the case walls on the bullet. It is accomplished by inserting a larger diameter bullet into a smaller diammeter case. The case walls hold onto the bullet due to brass springback (the tendency of the metal to return to it's original dimension.) The bullet expands the case walls, and the case walls want to shrink, hence the tension.

It is not possible to increase case tension by squeezing the case walls against the bullet by external pressure. The only way you can increase case tension is by running the case through a smaller die and reinserting the bullet.

If you run a loaded round through a sizing die such as the Lee FCD, and the FCD sizing ring is smaller in diameter than the loaded round, the ring will swage down the diameter of the round. The ring will apply pressure to the case walls which in turn will apply pressure to the bullet. Therefore, if the diameter of the loaded round is reduced, so is the diameter of the bullet. Because brass springs back more than copper and lead, the resized round will now have less case tension. This is because the bullet, being softer than the case, will remain smaller following this swaging operation. Basically, the case will spring back away from the bullet following this swaging.