Im building a 7mm-300 win mag on a rem 700. I want to shoot 180gr Bergers vld with Norma brass. Is anyone using this combination? What is your fired case neck diameter, your loaded round neck diameter and your re sized neck diameter? Im trying to figure out what my reamer neck clearance should be? Does anyone have a reamer setup for the 180? Any info regarding the round would be greatly appreciated!
7mm-300 Win Mag
- Thread starter HillbillySniper
- Start date
alf
Silver $$ Contributor
If you're considering the straight 7-300WM, I'd suggest at the very least going to a 30 Degree Shoulder - "7mm Mashburn", 4D has the Reamer for this: https://gooddebate.org/sin/mirror/library/weapons/firearms/cartridges/cd7mashburnmagnum.jpg
My loaded necks with Norma or Nosler brass were .313 I cut my chamber for .316. I see no reason to mess with fire forming by creating a different angle shoulder. The bullet is going to like a certain velocity node and going to a 30 degree shoulder will not get you to the next higher node. The only thing it will do is make you have to fire form. Just run the straight 7-300, neck it down in two steps, load bullets, and shoot. My reamer was cut for 180 Hybrids so if you choose a different bullet you will most likely need more freebore. You can call Dave Kiff and mention my reamer and make any freebore adjustments necessary. My print is on file with PTG the number is 41753. Both of my barrels had an accuracy node around 3165fps out of 28" Bartleins. Both were about 1-1.5 grains below any indication of pressure.
GSPV
A failure to plan is a plan for failure.
The Mashburn, at least as I remember it, was based on the 300 H&H case. Shortened and blown out. That’s a lot of work. Exceptional work requires exceptional benefits.
The 7-300 WSM is easy. 7 RSAUM is easy.
I’m a bit of a Lapua brass bigot...so, has anyone done a 7-308 Norma?
The 7-300 WSM is easy. 7 RSAUM is easy.
I’m a bit of a Lapua brass bigot...so, has anyone done a 7-308 Norma?
Last edited:
tclaunch
Silver $$ Contributor
I did a 7mm/308 Norma Mag Imp. Thought I could get by with neck sizing, but primer pockets died so fast it was a wasteful experiment.
The EASIEST 7mm wildcat to me for ease of making brass is the 7mm/300 Win Mag.
One pass thru a 7mm Rem mag die and you are ready for the rodeo.
The EASIEST 7mm wildcat to me for ease of making brass is the 7mm/300 Win Mag.
One pass thru a 7mm Rem mag die and you are ready for the rodeo.
Great info thank you very much. Sending a PM with a few more detailed questions. Hope you don’t mind.
Or just run the .300 WM Brass through the proper Mashburn Full length sizing Die and it works perfect. The 30 Degree Shoulder is known for Accuracy. I have formed the brass but don't own the Rifle.
But for what little extra speed I’d see the added case prep isn’t worth it to me. I thought the mashburns parent case was the 300 H&H? Shortened, necked down and blown out. Plus I can neck down the 300 win mag brass in my 7 rem mag die backed out. Resize with a type s 300 win mag and proper bushing. Swap out the 300 win mag seating stem from the die and replace with my 7mm seating stem. Load and go shoot. No fire forming shoulders or anything
Not a fan of the short mags. Plus I have a good supply of win mag brass 7mm bully’s and H1000
dragman
Site $$ Sponsor
Not a fan????
Short and fat is where it's at!!!!!
I can push the 180's at 3200fps with mine and if it was a repeater you could feed them out of a mag (because of the shorter parent case) and accuracy well I don't know anyone who hasn't got a WSM that wont out shoot a regular mag.
My 7WSM would outrun my Rem Mag but would not come close to the 7-300 or 28 Nosler. I love the efficiency of the Short mags but they just can not compete with the larger case capacities and my WSM was built with enough freebore to get the boat tail junction seated at the neck shoulder junction on a long action.
dragman
Site $$ Sponsor
Mine will run 3200 fps with the 180's in my reamer with decent accuracy. I backed it off a pinch to hit the sweet spot. No doubt you can get more a little more from a Nosler, but how much are we talking? and still running under LA magazine lengths?
What is backing off a little? My WSM would run up to 3100 but there was no accuracy there. My 7-300 and 28 would run over 3200 with no accuracy there. The nodes were 2980 and 3165 respectively. What length barrel? You better hang on to that one. If I could repeatedly get 3200(or anything over 3050) with a temp stable powder out a 28" or less barrel with under 70 grains of powder it would be the last 7 I ever owned.
I would skip the Norma brass and run either ADG or Peterson if you can find it. Have 5-6 loadings on ADG 300wm brass running 215 Bergers at RUM velocities with no issues yet.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.