Bullet seating deeper under recoil

[Bowpredator85]

I have a 338 Norma Mag running AI, CIP length mags. Under recoil, with a brake the bullets are seating deeper into the case and mushrooming the tips. I have tried 2k and 4k neck tension with no luck. I've tried stretching the magazine spring, also with no luck. Does anyone have any experience with this or any ideas to fix it?

Thanks

 

[gohring3006]

Might try cushioning the mag box, where the tip contact.
Slop is a problem in mag box's. It gives the rounds room to move forward.
It will set back bullets especially in heavy cartridges.

 

[Bowpredator85]

Might try cushioning the mag box, where the tip contact.
Slop is a problem in mag box's. It gives the rounds room to move forward.
It will set back bullets especially in heavy cartridges.

Like a piece of rubber or something inside the front of the magazine so the bullets can't move forward? Can you expand on your idea please?

 

[huntaxhunta]

To exemplify the pressure issue, here's a plot from pressure measurements of how pressure changed with seating depth for one bullet shape (round nose), as it goes from touching the lands on the left, to very deep on the right, all with the same powder charge. You can see that, for this rifle cartridge (.30-06), pressure gets lower as the bullet gets away from the rifling and goes deeper into the neck, up to a point, then as you go still deeper, it rises again.

This is thought to happen because the deeper seating allows gas more time to bypass the bullet before the bullet gets to the lands, and that stalls the rise in pressure. But when it gets too deep, it takes away too much of the powder space, so it finally gets to the point that the amount of gas in too small a space overcomes the bypassing effect. The rise in pressure due to seating too deep can be corrected by reducing the amount of powder used.

 

[Bowpredator85]

I'm leaning more towards modifying the magazine to hold the rounds in place. I prefer to shoot suppressed and this is when it's the worst. It not only sets back the round but flattens the tip. This is where I believe crimping won't make any difference. I'll still have flattened tips at the very least. I have seen some ideas in a couple threads. One is putting a triangular piece vertically in the mag that contacts the datum and holds the round in place. The other is putting something in front of the tips to cushion them. Have you guys seen this done or know of any products out there for sale to do this?

 

[gohring3006]

Like a piece of rubber or something inside the front of the magazine so the bullets can't move forward? Can you expand on your idea please?

Not sure why, but I'm not getting notifications on threads. So sorry for the late response. But yes, you have to allow for your follower to operate properly. Might try adhesive backed Velcro. Also, adding a block somehow to reduce space in the mag. Sometimes we have to get creative.
Have you tried Magpaul mags?

 

[Bowpredator85]

Not sure why, but I'm not getting notifications on threads. So sorry for the late response. But yes, you have to allow for your follower to operate properly. Might try adhesive backed Velcro. Also, adding a block somehow to reduce space in the mag. Sometimes we have to get creative.
Have you tried Magpaul mags?

I'm not getting notifications either. Not sure what the deal is. This could work. I'm thinking like rubber or weather stripping type material. Something with some give and bounce back. I have not tried magpul mags. Do they make a CIP mag? What benefit would a magpul have?

 

[Bowpredator85]

I see magpul does make 338 mags. Learned something new. I know my CIP length accuracy international mags fit but the accurate mags do not. I have seekins precision bottom metal. I'll have to do some research on this.

 

[gohring3006]

I'm not getting notifications either. Not sure what the deal is. This could work. I'm thinking like rubber or weather stripping type material. Something with some give and bounce back. I have not tried magpul mags. Do they make a CIP mag? What benefit would a magpul have?

My mistake, I don't think they make one for the 338 Lapua bases cartridges. But if they did, they seem to be more custom contoured for the case, that would mean less movement, but still may not have solved the problem.

 

[gohring3006]

I see magpul does make 338 mags. Learned something new. I know my CIP length accuracy international mags fit but the accurate mags do not. I have seekins precision bottom metal. I'll have to do some research on this.

Nice, I wasn't sure. I would give one of those a try.

 

[Bowpredator85]

Nice, I wasn't sure. I would give one of those a try.

I looked into those magpul mags and they only allow for a 3.5" oal so this won't work for me as I'm at 3.670". However, I just learned of a magazine made by desert tech. It's called the DT SRS. The magazine is contoured to hold the case in place. I am going to contact them tomorrow about this mag. Just wanted to tell you about it Incase your ever in the same place I'm in now. Thanks for your input, it's greatly appreciated.