What bushings do I need?

Hey guys, I'm setting up a new build in 7-300 win mag. I have a Forster bushing bump die for my 300 win mag. What size bushings will I need to order for the 7-300? Is there a certain incremental process or amount to necking down from 300win to 7mm? Or all at once? Seems like it should be stepped down but I could totally be wrong. This is the first wildcat I've ever attempted. Any advice would be very helpful and appreciated. I want to build some dummy rounds soon to send off to make a reamer.

You are going to be stepping it down from about .336 to about .310 depending on your neck thickness. I stepped it down .010 at a time, then the final neck down was .308 I think, then expanded out for .002 tension.

Size down all at once.
Use a FL sizing die.
Make a dummy cartridge. Seat a bullet. Measure neck. Start with a bushing .003" smaller.

http://www.huntingtons.com/dies_caseform.html AND http://www.redding-reloading.com/online-catalog/58-bushing-range-chart

243winxb said:

Size down all at once.
Use a FL sizing die.
Make a dummy cartridge. Seat a bullet. Measure neck. Start with a bushing .003" smaller.

http://www.huntingtons.com/dies_caseform.html AND http://www.redding-reloading.com/online-catalog/58-bushing-range-chart

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He's already got a 300wm bushing die and is going to order custom dies. Wouldn't it be cheapest and easiest to just get a few bushings?

odoylerules said:

Forster bushing bump die

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Clucknmoan said:

Wouldn't it be cheapest and easiest to just get a few bushings?

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The bump die doesnt support the case body when the shoulder is pushed back. A bulge may form at the shoulder.

My bushing doesnt size all the way to the shoulder . Redding type S Fl sizing die.

If the shoulder is pushed back a lot, the neck may become thicker then normal, and or a donut may form. This may
require inside reaming and/or outside neck turning.



The chamber reamer can make adjustment for a thicker neck.

A 300 wm necked down to 7mm = a 7mm Rem Mag. The parent case for both is the 375 h&h.

See list of saami cartridges in 7mm. As for wildcats, see Huntington link.
https://www.longrangehunting.com/threads/anyone-own-a-7mm-300-win-mag.51404/
The OP read this whole thread, should know all.

243winxb said:

See list of saami cartridges in 7mm. As for wildcats, see Huntington link.
https://www.longrangehunting.com/threads/anyone-own-a-7mm-300-win-mag.51404/
The OP read this whole thread, should know all.



View attachment 81254

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Reading that marathon thread left me more confused honestly. I don't know if I'm heading in the right direction going with the 7-300wm. I thought all I needed to do was neck down my current 300win cases with my bushing die.

I would not use a bump die to neck down as stated above it does not fully support the case. Get a Redding F/L bushing die, your gonna have to change the expander button and possibly rod also. Your necks will get thicker that a typical 7mm possibly and become work hardened so I would anneal and F/L size again after annealing to iron out any neck imperfections. Skim turning the necks would not be a bad idea. The good thing about having a reamer built is you can have the correct freebore and neck dia for the bullet you want to shoot and brass. Just stick with whatever brass you choose because different manufacturers have different neck thickness. Good luck in your build.

I guess I misunderstood the OP intentions. I thought he wanted to load and fire a couple rounds to have a custom die ordered, not a reamer. Was that part edited??

A bushing bump die, or a FL bushing die should support the case as they size the shoulder/body like FL dies do. Bushing dies usually do not size the entire neck length. That is usually, but there are bushing dies that include the shoulder in the bushing, or machined to fully size a neck. I don't know about forster, their own description says nothing useful about it..

You might have to use an actual FL die. I would do a full anneal beforehand.
The necks will thicken considerably with downsizing. You might want to consider neck turning and appropriate chamber neck dimension.

Clucknmoan said:

I guess I misunderstood the OP intentions. I thought he wanted to load and fire a couple rounds to have a custom die ordered, not a reamer. Was that part edited??

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No I didn't edit that. I don't have the barrel chambered yet. It's my understanding that to get a good custom die made it has to be from fired brass. I'm still on step "A", figuring out how to properly resize my 300win cases down to 7mm

Don't have it chambered and don't even order the chamber reamer until you've made the cartridge on the bench and carefully taken measurements.
Otherwise, your chance of success comes down to luck.

If I have a custom reamer made from the dummy loads I make up and send to PTG, I shouldn't need custom dies right? The chamber should match perfectly, no fire forming, and all I'll need to do is size the neck and slightly bump the shoulder just like normal at that point?
I appreciate your guys help and patience with me. I've only been reloading 18months, and haven't ever had a custom reamer or dies made. I'd hate to buy the Redding type S die set, then have to get custom dies made after. I guess I don't see the benefit of customs at that point.
When you size down a 300 case to 7mm, does it lengthen the neck any? One issue I think I could have with my Forster die is, I don't believe I can adjust the depth of the sizing of the neck, or how far down towards the shoulder. It sets up simply to bushing size the outside neck and bump the shoulder back .001, which is great-normally all you need. Does the Redding die allow you to adjust the amount of the neck being sized?
#2 How would you guys proceed from this point? Step by step.
My thoughts are...get new 300wm brass or take some of my old fired stuff and-FL resize it, then step down the neck to hold the 7mm rounds.
When would you turn the necks for uniformity? After sizing I assume, or before? Also annealing-before or after sizing down?
Anything else?

Suddenly the 28 Nosler is looking good again! Ha