7mm-300 Win reloading

[fmajor]

Howdy All!!!

It's been awhile since I've posted (or even visited... life took an interesting turn).

I had a 7mm-300 Win put together (Lilja 26" 5 contour 1-9 twist) on a Rem700 with the original bolt. I know interest in the chambering is not as active as once it was, but am hoping some folks still load for/use it.

I'm wanting to run 160gr A-Frames and am working with SCC 7828 (Winchester brass and Remington 9 1/2M primers) and getting pressure at powder volume that shouldn't be a problem.

Hoping for 3150-ish velocity, but at 77grs of 7828, i'm getting a very slight ejector pin pressure mark (no bolt sweep).

I do have some H1000, but was thinking it was more suited for heavier pills?

Sure would appreciate any advice...

Thank you!

PS - I have searched extensively on this topic...

 

[MagnumManiac]

I don't own a 7-300WM, but, I do own a 7STW running Remington brass, also have a 300WM running Remington brass.
Both rifles are Rem 700's, blueprinted with PT&G one piece bolts.
I can run them both until I get ejector imprints, it appears it is due to the plunger spring being very stiff, because my Rem 700 LR with original bolt does not do this, nor does my Sendero in 300WM.
I tested mine by depressing them manually, they were definitely stiffer than either factory plunger and appeared to not go as deep into the recess.
Maybe you have similar, or, it could be a tighter chamber and bore issue.

Cheers.

 

[Tiny Tim]

You don't say what load you are at or your velocity. Those bits of info may be helpful. I'm not familiar enough with the powder, but could you be too low in your charge? Many powders don't do well at reduced charge weights. The above requested info may help others with more experience to chime in.

 

[FEENIX]

Howdy All!!!

It's been awhile since I've posted (or even visited... life took an interesting turn).

I had a 7mm-300 Win put together (Lilja 26" 5 contour 1-9 twist) on a Rem700 with the original bolt. I know interest in the chambering is not as active as once it was, but am hoping some folks still load for/use it.

I'm wanting to run 160gr A-Frames and am working with SCC 7828 (Winchester brass and Remington 9 1/2M primers) and getting pressure at powder volume that shouldn't be a problem.

Hoping for 3150-ish velocity, but at 77grs of 7828, i'm getting a very slight ejector pin pressure mark (no bolt sweep).

I do have some H1000, but was thinking it was more suited for heavier pills?

Sure would appreciate any advice...

Thank you!

PS - I have searched extensively on this topic...

As with anything else, YMMV. Depending on the source data, the .300 WM has ~10-12g H2O advantage over the 7MM RM, so you can use that difference as your baseline reference point. As with everything else, always approach with caution and monitor pressure signs in the process. I did not do an extensive search, but below is a short yield of my effort. Good luck!

- https://www.longrangehunting.com/threads/7mm-300-win-mag-loads.223009/
- https://www.longrangehunting.com/threads/7-300-loads.136055/
- https://www.longrangehunting.com/threads/7-300-win-mag-300-and-500.245612/
- https://longrangeonly.com/forum/threads/7-300-with-195-bergers.3614/

 

[fmajor]

You don't say what load you are at or your velocity. Those bits of info may be helpful. I'm not familiar enough with the powder, but could you be too low in your charge? Many powders don't do well at reduced charge weights. The above requested info may help others with more experience to chime in.

Hi Tim -
Thx for the reply. I haven't chrono-ed anything yet....

I ran a test looking for pressure from 74grs to 78grs to get an idea where to start 'drilling down'. Pressure indicated with slight ejector/plunger pressure at 77grs. I had loaded some at 78grs, but didn't want to push past 77grs.

Any thoughts on H1000 achieving better velocity with 160gr bullets than the 7828SSC I'm using?

TIA!

 

[fmajor]

H

As with anything else, YMMV. Depending on the source data, the .300 WM has ~10-12g H2O advantage over the 7MM RM, so you can use that difference as your baseline reference point. As with everything else, always approach with caution and monitor pressure signs in the process. I did not do an extensive search, but below is a short yield of my effort. Good luck!

- https://www.longrangehunting.com/threads/7mm-300-win-mag-loads.223009/
- https://www.longrangehunting.com/threads/7-300-loads.136055/
- https://www.longrangehunting.com/threads/7-300-win-mag-300-and-500.245612/
- https://longrangeonly.com/forum/threads/7-300-with-195-bergers.3614/

Hey Feenix!

Thx for the linky's!

I've read all of those except the "7-300-loads" and that yielded GOLD!

I'm noting that not many folks are using the 7828SSC which surprises me b/c it's supposed to be just a bit faster than H1000 and possibly similar to RL33(?) so should be great for 160's. I had great hopes for the 160gr weight with it....

Conversely, a great many (most?) have had excellent results with H1000 (i have 8lbs thankfully), but it seems most are running 180gr class bullets with it and I wanted to stick around 160-175grs.

As a baseline, since I'm using 300 Win Mag cases, I look to 300 Win Mag load data....

Is this a mistake?

 

[MagnumManiac]

I would try H1000 regardless, it is far more stable than any IMR powder.
It gives me great performance in my 300WM.

Cheers.

 

[FEENIX]

H

Hey Feenix!

Thx for the linky's!

I've read all of those except the "7-300-loads" and that yielded GOLD!

I'm noting that not many folks are using the 7828SSC which surprises me b/c it's supposed to be just a bit faster than H1000 and possibly similar to RL33(?) so should be great for 160's. I had great hopes for the 160gr weight with it....

Conversely, a great many (most?) have had excellent results with H1000 (i have 8lbs thankfully), but it seems most are running 180gr class bullets with it and I wanted to stick around 160-175grs.

As a baseline, since I'm using 300 Win Mag cases, I look to 300 Win Mag load data....

Is this a mistake?

Excellent! The H1000 has longitudinal real-world success with the .300 WM, esp. with the 215 Berger. "I" would use the .300 WM load data as the baseline, but work up to it with caution, and monitor pressure signs in the process. Good luck!

 

[Tiny Tim]

Hi Tim -
Thx for the reply. I haven't chrono-ed anything yet....

I ran a test looking for pressure from 74grs to 78grs to get an idea where to start 'drilling down'. Pressure indicated with slight ejector/plunger pressure at 77grs. I had loaded some at 78grs, but didn't want to push past 77grs.

Any thoughts on H1000 achieving better velocity with 160gr bullets than the 7828SSC I'm using?

TIA!

Sorry, I have zero experience with 7828. H1000 is a very popular powder and certainly worth a try. H4831 is another good powder for the general case type/capacity and is slightlyfaster as well. It's generally not the fastest, but one of the most accurate.

 

[FEENIX]

Sorry, I have zero experience with 7828. H1000 is a very popular powder and certainly worth a try. H4831 is another good powder for the general case type/capacity and is slightlyfaster as well. It's generally not the fastest, but one of the most accurate.

I have tried the IMR 7828 SSC, H1000, and H4831 SC with very good success in multiple cartridges requiring powders in their burn rate.

 

[yobuck]

Ive been using 7828 with 162 gr Hornady BTHP bullets since shortly after that powder was introduced in my 7x300 WBYS.
with standard 700 actions with 26" to 30" barrels.
I would chronograph your load, you might be surprised at your velocity.
My velocity depending on the temperature, runs around 3350 with 78 grains.
80 grains shows a heavy bolt lift.
I would be loading just one round and shooting over a chronograph, then increase 1/2 gr for one round till you find pressure, then back up 1/2 gr and start looking for accuracy with seating depth.
Again, the door slams hard and quick with 7828, so your cool weather load might be a bit much in warmer temps.
We dont shoot our hunting guns in warm weather for that reason.

 

[the bullet man]

4831sc for bullets under 200g is my opinion.

 

[Clyde M]

7-300 Weatherby 150TTSX 3400 FPS 26" barrel / 120TTSX 3700 FPS 24" Barrel, both with Ramshot Magnum, no signs of pressure, very accurate 5/16" groups at 100 yards.

 

[fmajor]

I would try H1000 regardless, it is far more stable than any IMR powder.
It gives me great performance in my 300WM.

Cheers.

Thanks! I have H1000 so will just give that a go - it seems to give great results.