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7-300 Long Range Improved

7.62 Gunner

Well-Known Member
Joined
Jan 9, 2022
Messages
1,011
Location
Idaho
I recently had Dave Manson design a reamer for me based off the 300 WSM and soon to be released ADG brass.
It's called the 7-300 Long Range Improved (LRI)
It's a necked down 300 wsm with the shoulder blown out to 45 degrees.
I decided on 45 because 40 didn't seem like enough improvement on the 35 degree shoulder of the parent case, also I wanted to maximize case capacity and 100% stop case growth.
Plus no one's doing 45 degree shoulders so I just wanted to try it.

I love the WSMs for their effortless accuracy and efficiency, the most accurate rifle I ever owned was a 7 wsm.
My objective was to build a lightweight 18" 7mm that would maximize velocity with 180/195 Bergers for my primary elk rifle.
I hunt elk in everything from thick timber to cross 800 yard clear-cuts here in Idaho, a suppressor is a must in this invironmemt where shot opportunities can come and go in a matter of seconds.
I cover lots of miles in thick mountainous terrain, and believe I've built the perfect rifle for the task

I had McGowen barrel make me a factory tikka contoured 18" 8 twist prefit with the muzzle flared up to .730 for 5/8×24 threads
The barrel came in at 2 lbs which is even lighter than I'd expected!
All set up with a vx5 HD in talley rings with the factory stock, and 9" Banish 30 suppressor it weighs 8lbs 5 oz.
I'm about a month out on a custom CF lightweight LR stock from MPI, it should come in sub 20 oz so the final weight will be around 7lbs 13 oz.

I'm still waiting for my custom dies from Hornady but in the meantime I used a 270 wsm die and a .284 expander to size a few winchester cases down.
I fire formed with 15 grains of unique topped with TP and got a near fully formed case, fully formed capacity is 82 grains with WW brass.
Pretty darn good considering the parent case measured 79 grains in 30 cal
Shooting 195 EOLs I worked up to pressure while zeroing at 100 yards, and ended up at 2815 with 70 grains of N570!
Accuracy is outstanding even with crappy brass, I'm getting sub 1/2" groups edge to edge.
More load data to come when I get the dies, and ADG brass.

1. Fireformed case and necked down 300 wsm
20220118_160714.jpg

2. 7-300 LRI 195 next to 30 Nos 220 LRHT
20220123_092315.jpg
2a. Loaded with 195's
20220125_090219.jpg

3. Scoped and suppressed
20220119_114312.jpg

4. Muzzle flare
20220118_162826.jpg

5. Setup
20220123_092748.jpg

6. 100 yard group
20220125_092751.jpg
 
looks awesome and great job sticking with the project till the end

the short mag case finally improved properly, love it !
 
looks awesome and great job sticking with the project till the end

the short mag case finally improved properly, love it !
Well thank you
It's been fun and I'm twitching to get my dies and ADG brass for proper load development.
On that note I spoke with a representative from ADG today and they're about to finish a big run of WSM brass.
Unknown munitions, Blue collar, and Creedmoor sports are supposed to get it in approx 2 weeks.
Creedmoor is accepting pre-orders
 
Great news !
I have three Tikka T3's in 300 WSM and have been waiting for the brass to be done

Have recently bought stuff from all 3 places you mentioned and they all ship fast !
 
Update:
I got some ADG brass and ended up at 2725 with RL26 and 195s, N570 was way too dirty with my suppressor.
I've been wanting to shoot some lighter bullets and thanks to @8×68s I scored some 175 ELDXs.
They showed up tonight and I loaded up 3 test rounds .050 off the lands, I started at 65 grains of RL 26 which is my max load with 195s and loaded the other two at 66 and 67.
I'm very surprised by the velocities I was able to achieve

65 grains went 2820
66 went 2880
And 67 got me to 2940!
I never hit pressure but 67 grains was starting to flatten the primer.

I shot the string at 200 yards and couldn't believe the result, a .7" group.
More testing and drop validation to come but so far it's looking like I need to find more 175s.
Ignore the jump on my target.. it wasn't .5"
 

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Just what I need - temptation for another caliber like that :)
I already have 7mm-300 Win Mag, 6.5-300 Wby Mag, 6.5-'06 AI
I really like all of them.
Yours sounds like an intriguing caliber.
 
Cool project. Are you having any feeding issues with the 45° shoulder? I've contemplated something similar but with a longer neck. Then I found the sherman magnums and realized it had already been done lol
 
I recently had Dave Manson design a reamer for me based off the 300 WSM and soon to be released ADG brass.
It's called the 7-300 Long Range Improved (LRI)
It's a necked down 300 wsm with the shoulder blown out to 45 degrees.
I decided on 45 because 40 didn't seem like enough improvement on the 35 degree shoulder of the parent case, also I wanted to maximize case capacity and 100% stop case growth.
Plus no one's doing 45 degree shoulders so I just wanted to try it.

I love the WSMs for their effortless accuracy and efficiency, the most accurate rifle I ever owned was a 7 wsm.
My objective was to build a lightweight 18" 7mm that would maximize velocity with 180/195 Bergers for my primary elk rifle.
I hunt elk in everything from thick timber to cross 800 yard clear-cuts here in Idaho, a suppressor is a must in this invironmemt where shot opportunities can come and go in a matter of seconds.
I cover lots of miles in thick mountainous terrain, and believe I've built the perfect rifle for the task

I had McGowen barrel make me a factory tikka contoured 18" 8 twist prefit with the muzzle flared up to .730 for 5/8×24 threads
The barrel came in at 2 lbs which is even lighter than I'd expected!
All set up with a vx5 HD in talley rings with the factory stock, and 9" Banish 30 suppressor it weighs 8lbs 5 oz.
I'm about a month out on a custom CF lightweight LR stock from MPI, it should come in sub 20 oz so the final weight will be around 7lbs 13 oz.

I'm still waiting for my custom dies from Hornady but in the meantime I used a 270 wsm die and a .284 expander to size a few winchester cases down.
I fire formed with 15 grains of unique topped with TP and got a near fully formed case, fully formed capacity is 82 grains with WW brass.
Pretty darn good considering the parent case measured 79 grains in 30 cal
Shooting 195 EOLs I worked up to pressure while zeroing at 100 yards, and ended up at 2815 with 70 grains of N570!
Accuracy is outstanding even with crappy brass, I'm getting sub 1/2" groups edge to edge.
More load data to come when I get the dies, and ADG brass.

1. Fireformed case and necked down 300 wsm
View attachment 334403

2. 7-300 LRI 195 next to 30 Nos 220 LRHT
View attachment 334404
2a. Loaded with 195's
View attachment 334409

3. Scoped and suppressed
View attachment 334405

4. Muzzle flare
View attachment 334406

5. Setup
View attachment 334407

6. 100 yard group
View attachment 334408
WHOA! That's mighty sexy. I am looking forward to some harvest pictures.
 
Cool project. Are you having any feeding issues with the 45° shoulder? I've contemplated something similar but with a longer neck. Then I found the sherman magnums and realized it had already been done lol
I also designed an improved reamer (45° shoulder) that Dave Manson built for me for my next project build. It was an initial concern, but ICL (45°) and Tejas (50°) wildcats do not seem to have feeding issues. We shall see ...
 
So, basically a 7 WSM or 7/300WSM right:)

With a steeper shoulder though

We are a nutty bunch eh:)
 
Cool project. Are you having any feeding issues with the 45° shoulder? I've contemplated something similar but with a longer neck. Then I found the sherman magnums and realized it had already been done lol
It feeds like butter but keep in mind the tikkas are a center feed magazine which are the most forgiving.
Honestly though I wouldn't use anything besides a tikka for short mag builds, they're basically an XM action without the drama
So, basically a 7 WSM or 7/300WSM right:)

With a steeper shoulder though

We are a nutty bunch eh:)
Haha
Yeah you're right, the capacity is virtually identical to the 7wsm, I had one in the past and loved it but my main reasons for doing what I did are as follows:

The 7 wsm doesn't have good brass available, I thought about necking down ADG and fireforming to standard 7 wsm dimensions but figured at that point why not improve the angle to stop case growth.
A simple 7-300wsm would have been fine but I got 3 more grains of capacity by improving it, and I maintained the longer neck.
 
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