Tell me about necking down for 7-300 win mag

[victor3ranger]

Thinking about this one.
Who here shoots the 7-300 win mag?
How exactly are you necking it down to 7mm?
Also, which die are you using to resize the neck and bump the shoulder??
I want to hear how you guys have done this

 

[Slick8]

Call and talk to Robert at Alamo Precision Rifles. He built several of them a few years back.

What I remember is the typical you'd expect, it's a barrel burner.

Necking is pretty simple. Anneal your cases if not already done. Lube them really well and run through a 300wm bushing die with a 7mm bushing. The annealing is optional but preferred.

I just ran some 8mm rem through through a 30 then 7mm bushing to make some 7stw brass for my dad.

Not sure why you wouldn't go 28 nosler. It's a superior case imo.

I myself just built a light weight hunter in 30-28 nosler throated for heavies.

 

[victor3ranger]

I want to stick with the belted just because it's going to be easier to get brass and
Just cause I guess

 

[Mike Matteson]

If you are using 300WM cases. Get a bushing die and some bushing. Take a couple of steps to reduce the neck down. I wouldn't try it in one step. It maybe can be done, Not for sure. Most of the belted mag can be change from one caliber to another by sizing the cases. Check your case length after sizing them. May grow some.
I have done a lot with 25/06 rifles. My sons and all shot 25/06, but a little different chamber. So I use different brass to identify which case when to which rifle.

 

[Elk Hunter 338]

Done a ton of them, and Probably one of my favorite 7mm's

300 win mag Peterson or ADG easy to make two bushing steps using redding dies .. load and let er eat!! I dont do any trimming or anything on first go i want the case to grow as much as possible the first firing then square it all up after that... have not had one yet with this process not shoot 1/2 out of the gate

 

[victor3ranger]

Done a ton of them, and Probably one of my favorite 7mm's

300 win mag Peterson or ADG easy to make two bushing steps using redding dies .. load and let er eat!! I dont do any trimming or anything on first go i want the case to grow as much as possible the first firing then square it all up after that... have not had one yet with this process not shoot 1/2 out of the gate

Do you have a link for the die and bushings you used?

When you resized to reset the neck and bump the shoulders did you do that with a 7rem mag fl sizing die or something else

 

[scpaul]

I've used Lee crimp dies to reduce the neck before I fireformed the shoulder, length, and fine tune the straightness of the neck to the case body.

 

[victor3ranger]

I've used Lee crimp dies to reduce the neck before I fireformed the shoulder, length, and fine tune the straightness of the neck to the case body.

30 cal crimp die? Never heard it done that way

 

[scpaul]

7mm crimp die and I rotate the brass as I gradually reduce the neck. Sometimes you have to work the brass around to get it to go in. I forgot to mention that the die is in the press and I insert the brass from the top then raise the ram and work the brass up and down the neck and rotate it some each time so that the crimp lines don't align. I got impatient, I'd been waiting for custom dies for 6 months. I finished the rifle 3 months or more before I got the dies.

 

[victor3ranger]

Call and talk to Robert at Alamo Precision Rifles. He built several of them a few years back.

What I remember is the typical you'd expect, it's a barrel burner.

Necking is pretty simple. Anneal your cases if not already done. Lube them really well and run through a 300wm bushing die with a 7mm bushing. The annealing is optional but preferred.

I just ran some 8mm rem through through a 30 then 7mm bushing to make some 7stw brass for my dad.

Not sure why you wouldn't go 28 nosler. It's a superior case imo.

I myself just built a light weight hunter in 30-28 nosler throated for heavies.

I have never used bushing dies before, so when I look for a die to do this do I need to get a Redding 300 win mag neck sizing die type S?
And which bushings do you think I need?

 

[VinceMule]

7 Practical I think is what you are referring to in the 7/300. I have the reamer, never used it.

When necking down, Put a heavy chamfer on the outside of the case mouth, lube with Lee sizing wax, run through the 7 Practical die
Die, easy does it, size a little down, back off, then go a tad more, back off, then a tad more....Done!

The key is the heavy chamfer and the lee sizing wax in the toothpaste-type tube, the best stuff I have found yet.

Manson reamer has the 7 Practical dies in stock.

 

[victor3ranger]

7 Practical I think is what you are referring to in the 7/300. I have the reamer, never used it.

When necking down, Put a heavy chamfer on the outside of the case mouth, lube with Lee sizing wax, run through the 7 Practical die
Die, easy does it, size a little down, back off, then go a tad more, back off, then a tad more....Done!

The key is the heavy chamfer and the lee sizing wax in the toothpaste-type tube, the best stuff I have found yet.

Manson reamer has the 7 Practical dies in stock.

The way I understand which I might be wrong but isn't the 7-300 win mag different than the 7 practical?? Isn't the shoulder angle different???

But either way the information you gave sounds like if I chamfer the outside of the case neck really good and lube it well I should be able to slowly neck down the 300 brass using my 7 rem mag die?!?

 

[Calvin45]

The way I understand which I might be wrong but isn't the 7-300 win mag different than the 7 practical?? Isn't the shoulder angle different???

But either way the information you gave sounds like if I chamfer the outside of the case neck really good and lube it well I should be able to slowly neck down the 300 brass using my 7 rem mag die?!?

Pretty sure the 7mm practical is Nathan Fosters brainchild and is in fact just a 7-300 win mag.

 

[scpaul]

There are actually 3 variations. Nathan Foster did the 7 Practical, Ackleyman did the first 7 Valkyrie Magnum which has some minor changes (case taper and shoulder?) from the practical and mine which has the least case taper and shortened the throat and I think that I flattened the shoulder another 2/3*. It's been about 5 years ago so some of the info may be slightly off. My drawing is at PT&G, I'm not sure about the others. It doesn't have the "Magnum" tag on the drawing but in the meantime the little 6mm (?) Valkyrie came out. I got the small Valkyrie stuff instead of mine by mistake and had to wait extra time. That's why I came up with the unusual way of necking it down fron .30 to 7mm. I started using the "Magnum" monacker to help clarify which one it is. If you like you can look them all up on Goggle but they are like I said about 5/6 years old. If you like, I can try to get you my drawing number if you want. Mine has very similar case capacity as the 7STW but with the mods it shouldn't burn the throat and lands as fast as the 7STW.