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 spring in the magazine out, also with no luck. Does anyone have any experience with this or any ideas to fix it?
Thanks

 

[natdscott]

Lee crimp.

 

[BowPredator85]

Shooting berger eh 250’s. No crimping groove on the bullet.

 

[natdscott]

Wondered about that. Uh...how about a taper crimp. Does Redding make one for it?

 

[BowPredator85]

Wondered about that. Uh...how about a taper crimp. Does Redding make one for it?

Not sure. I’ll look into it. Problem with that I foresee is increased pressure. I’m already in the spectrum of max. Idea thrown at me was cushioning the inside front of the mag. Not sure how to go about it exactly yet if it would even work. There is room in there to work with.

 

[natdscott]

Not sure. I’ll look into it. Problem with that I foresee is increased pressure. I’m already in the spectrum of max. Idea thrown at me was cushioning the inside front of the mag. Not sure how to go about it exactly yet if it would even work. There is room in there to work with.

Take it back 4-5 grains at least, trim ALL your casings by hand on a Wilson (or at least something that is that consistent with regards to length), and taper crimp lightly.

It will probably increase pressure a little, but hopefully it will effectively increase release force enough to hold the bullets in place.

I agree with you though that more than 0.004" tension doesn't do anything good for match bullet jackets, particularly the J4s.

-Nate

 

[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?

 

[whatsupdoc]

No experience with this but if you want to experiment you could try 2 pieces of round stock vertically in the mag set at the case shoulder drill 4 holes in the mag and tack weld them from the outside. Then cut reliefs for the follower.

 

[BowPredator85]

No experience with this but if you want to experiment you could try 2 pieces of round stock vertically in the mag set at the case shoulder drill 4 holes in the mag and tack weld them from the outside. Then cut reliefs for the follower.

I think I’m gonna try this out. I’ll post my results

Thanks

 

[Bradu]

No experience with this but if you want to experiment you could try 2 pieces of round stock vertically in the mag set at the case shoulder drill 4 holes in the mag and tack weld them from the outside. Then cut reliefs for the follower.

Pretty sure the spring will be a problem with your idea

 

[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. Not sure how this would work though without being in the way of the spring. 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?

 

[Ledzep]

Shooting berger eh 250’s. No crimping groove on the bullet.

You don't need one. You don't want to put a death crimp on it (You WILL see accuracy degrade if you do), but you can apply a very light crimp (I like the LEE crimp dies) to match bullets without a cannelure without noticing any accuracy-degrading deformation of the bullet. I do this with my AR-15 loads (75gr Hornady HPBT) because otherwise they will do the same thing... slosh around in the magazine and get pushed into the case further, then with the semi-auto I get the added effect of inertial pull forward out of the case when it slams into battery. Crimping fixed it, and brought group size and MV spreads down.

 

[B y r o n]

You talk about using neck tension but are the necks clean and dry when the bullet is seated? When reloading we sometimes rush things and skip steps. With a little more neck tension and ensuring they are clean and dry you should get better results. A taper crimp can apply more tension if needed but as already stated be careful not to over do it or you deform the bullets.

 

[waveslayer]

I had this same problem with my Lazzeroni, I had to place a thin piece of rubber on the inside of the mag. This helped a little. I cleaned all the necks and had the same issue. I even placed a bigger brake on there.

Or you can go top the extreme and get a DT SRS. My. 338 Norma AI had no issue because their mags are designed to index the cases by their shoulders. That solves your problem, but may not be realistic for you

 

[RTH1800]

Pre war magnum Mauser actions sometimes had a shoulder guide in the mag well to prevent this.

 

[Ledzep]

You talk about using neck tension but are the necks clean and dry when the bullet is seated? When reloading we sometimes rush things and skip steps. With a little more neck tension and ensuring they are clean and dry you should get better results. A taper crimp can apply more tension if needed but as already stated be careful not to over do it or you deform the bullets.

Changing out bushings to change neck diameter does not have much appreciable effect on "neck tension", at leas in this regard. From 0.0000 to about 0.0015" there is a change. Everything from .002 on has almost no measurable effect. I've tested it in a couple AR's and found no significant change in the numbers (how far in or out the bullet slides in the magazine and chambering) with .002, .004, and .006" undersize necks.

My gut guess is that you exceed the elastic response of the case neck very soon, and everything else is just plastic deformation with a more-or-less leveled off elastic "hold" on the bullet. I'd like to test it further to confirm it beyond just a couple informal tests but haven't had the time yet.

Crimping creates a small mechanical interlock, vs. friction alone, and does work well in my experience. You can go too far and cause accuracy to fall off, but a light crimp, even without a cannelure works and maintains accuracy-- even improved ES/SD in my case.

 

[BowPredator85]

I had this same problem with my Lazzeroni, I had to place a thin piece of rubber on the inside of the mag. This helped a little. I cleaned all the necks and had the same issue. I even placed a bigger brake on there.

Or you can go top the extreme and get a DT SRS. My. 338 Norma AI had no issue because their mags are designed to index the cases by their shoulders. That solves your problem, but may not be realistic for you

I called AI and they only make the 338 Norma mag for their AX chassis, not the single stack AI CIP length mag which is what fits my rifle. This desert tech mag looks like it may be the ticket. I am going to call them tomorrow to see if it will fit my rifle. Thanks for the lead!

 

[Bradu]

I called AI and they only make the 338 Norma mag for their AX chassis, not the single stack AI CIP length mag which is what fits my rifle. This desert tech mag looks like it may be the ticket. I am going to call them tomorrow to see if it will fit my rifle. Thanks for the lead!

Desert tech mags are specific to a desert tech. Not even close to fitting anything else.

 

[BowPredator85]

Figures...it seems there’s no one that makes one like this. Thanks

 

[B y r o n]

Changing out bushings to change neck diameter does not have much appreciable effect on "neck tension", at leas in this regard. From 0.0000 to about 0.0015" there is a change. Everything from .002 on has almost no measurable effect. I've tested it in a couple AR's and found no significant change in the numbers (how far in or out the bullet slides in the magazine and chambering) with .002, .004, and .006" undersize necks. . . .

I'm sorry but I don't think a comparison of standard AR rounds to .338 Norma Mag is fair considering that the Norma Mag has roughly 10 times the recoil energy of the AR.

 

[Bradu]

How much room is between the tip of the bullet and the front of the magazine? I'm just curious because I'm having a hard time picturing the tips of the bullets being mushroomed. I'm not doubting that it's happening, just trying to help you figure it out.

 

[Ledzep]

I'm sorry but I don't think a comparison of standard AR rounds to .338 Norma Mag is fair considering that the Norma Mag has roughly 10 times the recoil energy of the AR.

To the bullets sliding back into the case under recoil?

What do you not think is applicable?

 

[jamiecarr]

Lee crimp.

Yep, I use it with pretty good results. Best $30 die I ever bought.

 

[BowPredator85]

How much room is between the tip of the bullet and the front of the magazine? I'm just curious because I'm having a hard time picturing the tips of the bullets being mushroomed. I'm not doubting that it's happening, just trying to help you figure it out.

There is about .980 between the tip and front of mag. After only two firings the remaining in the mag are pushed back on average .024 and the tips are flattened.