7MM - Need to make a choice

[AZShooter]

Based on today's shortage of brass the decision on which 7mm to make might be determined by availability.

I solved that issue with the latest 7mm I built. I necked down 375 Ruger brass without relocating the shoulder as was done with the 7mm LRM. Haven't noticed any issues with the short neck.

I decided neck it down with dies I had on hand. It took 8 steps and some neck turning but I got it done. PT&G sold me a reamer. The performance has been fantastic with two rifles I chambered myself. Both rifles showed a preference for 180s. The 162 or 168s had a slight velocity increase over the 7 rem mag. The 180s pulled away from 7 rem mag's velocities for a definite increase in performance.

Sure it was a great deal of work, BUT I have an unlimited supply of brass! Every time I walk through Sportsmans I see 2-4 boxes. I have several hundred pieces now. Meantime the other bins have remained empty for months.

I'd say buy the brass then go ahead and build the 7mm. It is stunning how rare some cases have become.

Be sure to tell us what you ended up doing. Always enjoy reading what others are doing.

 

[Lefty7mmstw]

Based on today's shortage of brass the decision on which 7mm to make might be determined by availability.


I'd say buy the brass then go ahead and build the 7mm. It is stunning how rare some cases have become.

Be sure to tell us what you ended up doing. Always enjoy reading what others are doing.

As to the 7stw and 7x300 as choices...
Stw brass is a bit rare (rem gone- nosler spendy) at present but other fl belted cartridges (especially 375) are rather common and can be formed. 300 win brass is a bit rare but you can shoot out (if you have a 300)or knock down factories if you get in a bind as those are available, then neck either down to 7mm. The 7 rum brass is actually available at times but you need to be serious about low round count if you go there. Get a load and shoot other rifles for practice.

 

[angus-5024]

The STW is exactly what your looking for. I think they start losing accuracy at about 800 and don't shoot out until 1500. That's enough for a lifetime of hunting with 20 rounds of practice per year.

 

[rifletuner]

So given all the feedback, I am most inclined to make a 7mm/375 Ruger. Gives me a nice, modern unbelted case, with performance around the 7/300 WM to 7mm STW. The only down side is that I will have to buy a reamer, though I have already emailed PTG to see what they have already made for others in this chambering. Then I need to find a die set, and do some forming (and probably case neck turning).

Thanks for all the input.

 

[rifletuner]

I hear ya, mine shot almost to good to be true, just not for very long. For a guy that strictly hunted inside 600 yards and didn't want to practice to stay proficient and long range , kinda defeats the purpose of a big 7 but it would prob last along time. I for one don't feel confident taking long shots without practicing those long shots enough to consistantly make them. To many things can go wrong even if your consistent enough to make them, so for me to ethically take the long shots I practice a lot. Had I kept my shooting inside 600 yards that 7rum would probly still be with me.

I agree. Except that I do not believe that I need to practice extensively with the big 7mm, as long as I am getting relevant practice with other rifles. In my case, I have other rifles in 22, 6mm, 6.5mm, 30 cal and 338 that I can use for practice at various distances. That way I keep the really hard on bore cartridges for limited shooting, and primarily hunting. I have always found that good quality shooting practice is useful, and translates very well to use with other rifles.

 

[rifletuner]

Based on today's shortage of brass the decision on which 7mm to make might be determined by availability.

I solved that issue with the latest 7mm I built. I necked down 375 Ruger brass without relocating the shoulder as was done with the 7mm LRM. Haven't noticed any issues with the short neck.

I decided neck it down with dies I had on hand. It took 8 steps and some neck turning but I got it done. PT&G sold me a reamer. The performance has been fantastic with two rifles I chambered myself. Both rifles showed a preference for 180s. The 162 or 168s had a slight velocity increase over the 7 rem mag. The 180s pulled away from 7 rem mag's velocities for a definite increase in performance.

Sure it was a great deal of work, BUT I have an unlimited supply of brass! Every time I walk through Sportsmans I see 2-4 boxes. I have several hundred pieces now. Meantime the other bins have remained empty for months.

I'd say buy the brass then go ahead and build the 7mm. It is stunning how rare some cases have become.

Be sure to tell us what you ended up doing. Always enjoy reading what others are doing.

I will let you know once I get into the build. Next immediate challenge will be to see if I can find a 7mm barrel with a 1/8" twist!

What die set are you using for your reloading your 7/375, once you have gotten through the forming steps, and actually into shooting?

 

[Edd]

If you like the 7-375, why not just build a 7LRM?

 

[rifletuner]

If you like the 7-375, why not just build a 7LRM?

Because its a proprietary cartridge from one vendor. I cant go order a reamer, die set, etc off the shelf as far as I know.

 

[AZShooter]

Fergus,

Gunwerks loaned a reamer to someone here. Gunwerks has the brass, and dies at fairly reasonable prices. I'd give them a call.

What I did was for the sake of a challenge and I have around 80 die sets. If you are still interested here are the steps on how I did it:

Procedure for necking down 375 Ruger

1) Hornady 338 RCM FL die
2) 300 RUM FL die to taper mouth of case
3) 7 RUM seater die followed by FL to reduce neck dia
4) Whidden 338 RCM bushing die with .329 bushing
5) Whidden 338 RCM bushing die with .312 bushing
6) Open up with K and N mandrel, neck turn to .013" neck wall thickness
7) Run brass into Whidden 338 RCM bushing die using .310 bushing

 

[rifletuner]

Thanks for the insight into you case forming process for this case.

Not sure that the guys at Gun Werks will want to send me a loan reamer here in Australia. I might see if I can get dies off them though. Brass is probably not worth the effort considering the permits involved.

 

[MudRunner2005]

Thanks for the insight into you case forming process for this case.

Not sure that the guys at Gun Werks will want to send me a loan reamer here in Australia. I might see if I can get dies off them though. Brass is probably not worth the effort considering the permits involved.

You have to have permits to buy brass or reloading supplies in Australia??? That's bullcrap. I believe i'd have to move somewhere free. LOL

 

[rifletuner]

You have to have permits to buy brass or reloading supplies in Australia??? That's bullcrap. I believe i'd have to move somewhere free. LOL

I mean I need a permit from the US department of state to export cases out of the USA.

 

[AZShooter]

Fergus,

I am sorry to hear of how difficult it is for you to import components from USA.

Perhaps you would be best served with a more common case. The 7mm/300 win mag would be much easier to form plus it has been around for a long time with many companies making it. Otherwise just stick with the 7mm Rem mag or some other standardized cartridge.

 

[Varmint Hunter]

It seems to me that the very first question that needs to be answered is "what quality brass is readily available?" before you can contemplate the remaining 1,000 questions regarding a custom build.

I'm kind of surprised that there is interest in building anything off the 375 Ruger case which I expect to disappear entirely. I own a 375 Ruger and have purchased enough Hornady brass to last the life of the bore, or at least the life of my shoulder. Maybe I should have just taken my own advice above.

Good luck