7MM-300 Winchester Magnum

[Desert Fox]

I'm in a process of building a light carrying hammer. I already have component on hand and just waiting for the action to arrive from Pennsylvania. I settled on 7-300 for practicality. I was planning on 28 Nosler chambering or 7MM Remington Magnum but ultimately settled on the 7MM-300 Winchester Magnum. I will be sending my dummy round to JGS to make the reamer for this build. The chamber will be throated for Berger 195 EOL. I would like to keep the weight at around 8 to 8-1/2 lbs including scope. The Proof Research barrel and Stocky VGS stock already has a combine weight of 4-3/4lbs. That'l leave me 3-3/4 lbs between the scope and the action.

 

[gbflyer]

Nice. Should really reach out there. Good call on JGS, quality outfit. The other is Manson.

Action from Pennsylvania you say? Borden?

 

[Desert Fox]

Nice. Should really reach out there. Good call on JGS, quality outfit. The other is Manson.

Action from Pennsylvania you say? Borden?

T&L 704 Action.

 

[SJB358]

Very cool DF. I really like my 7mm Mashburn Super. Did a little work with the 195 EOL before Elk season. H1000 got up to 2900 and Retumbo was tickling 3000.






I like the 7-300/Mashburn a bunch. Really makes a perfect 8 and 1/2 pound hunting rifle. Can’t wait to see more details on it.

Right now I’m working with the 175 Woodleighs and RL33.. I’m looking for 3000-3100 out of it. 33 has worked pretty well for me in the past. Good luck with your build.

 

[gbflyer]

Nice. Should really reach out there. Good call on JGS, quality outfit. The other is Manson.

Action from Pennsylvania you say? Borden?

T&L 704 Action.

Nice. And a great price too. No lefties yet, bet it's coming though. Are they making the bolt or getting it from Kiff?

 

[Desert Fox]

What's your twist and barrel lenght Scotty? Good to know that Retumbo works well on this cartridge.

 

[longrangehunter]

Should be a real shooter DF. I think Scotty used a 1:8" for his newer Mashburn, what did you go with?

 

[SJB358]

What's your twist and barrel lenght Scotty? Good to know that Retumbo works well on this cartridge.

25” and a 1-8 5R Bartlein.

 

[Desert Fox]

Should be a real shooter DF. I think Scotty used a 1:8" for his newer Mashburn, what did you go with?

8 twist.

 

[SJB358]

These are my results from 175 Woodleighs









Those danged RWS cases are worth the money.

 

[Desert Fox]

What's your twist and barrel lenght Scotty? Good to know that Retumbo works well on this cartridge.

25” and a 1-8 5R Bartlein.

Great. Mine is also 8 twist but 26" finish length.

You shoot without brake?

 

[SJB358]

What's your twist and barrel lenght Scotty? Good to know that Retumbo works well on this cartridge.

25” and a 1-8 5R Bartlein.

Great. Mine is also 8 twist but 26" finish length.

You shoot without brake?

No brake on mine. It’s a big pussycat in my opinion.

 

[DrMike]

Very cool build, Rommel. I have to love something that not everyone has or something that one doesn't see every day at the range.

 

[longrangehunter]

Scotty,

Looks as though there's a node @ 83.6-84.0 with that load with the flat velocity curve. Was the group showing a bug hole there, or the 82.2-82.6 area?

 

[TackDriver284]

Scotty,

Looks as though there's a node @ 83.6-84.0 with that load with the flat velocity curve. Was the group showing a bug hole there, or the 82.2-82.6 area?

I was looking at that 82.2 to 82.6 area too.

 

[SJB358]

I haven’t put either on paper yet fellas. I will though soon. I’d be just fine with either one shooting well.

I’ll post up what comes out though.

 

[Desert Fox]

I'm not seeing pressure sign on that primer. I necked down a once fired 300 Win Mag Federal Gold Medal Match case and seat the Berger 195 EOL. It seems like the case doesn't need to be neck turn.

 

[SJB358]

I'm not seeing pressure sign on that primer. I necked down a once fired 300 Win Mag Federal Gold Medal Match case and seat the Berger 195 EOL. It seems like the case doesn't need to be neck turn.

No pressure problems here Rommel.

I hate neck turning but I do have to inside neck ream when going from 300 Win to Mashburn Super but they do last forever.

 

[ShadeTree]

Whew! You boys are getting in over my head on those bad boys. I'd hate to be on the receiving end of those crushers. A sledgehammer riding on a rocket. Looking good.

 

[Desert Fox]

Well she's finally done. I hit a snag there for a while when the action started giving me problem therefore I was not able to developed loads for it. I finally got it ironed out and the rifle is ready for the upcoming hunt.