Just curious if anyone here has any experience with this cartridge. Looks like a well thought out 7mm-300 Win Mag and very tempting. Much like a Mashburn. I like the numbers on it being a little more than a 7 Remington Mag but not as harsh as a RUM or Nosler. Yeah, it’s a niche but a good one.

It’s really the same as a 7-300, 7 Mashburn, etc... all three are kissing cousins in capacity. I’ve enjoyed the Mashburn a bunch but as some folks like to point out, there isn’t any data out there so the best you can do is work up using 7 Wby data.

Same here. Looked at the Practical really hard but decided on the Mashburn, just for nostalgic reasons. 2 peas in a pod, very minute differences.

I read up on it and it looks interesting but, like you guys have said it’s basically a redo of the Mashburn. I think the Mashburn actually has a little less body taper and the same neck length roughly so the nod would go to the Mashburn for velocity ever so slightly. They state it’s nothing more to it but sizing 300 WM cases in the FL sizing die and fire forming with the loads on their site. Not sure what the Mashburn entails. It’s been a little while since I looked at what Dober PM’d.

I really enjoy working with the Mashburn!

It’s no better than the 7-300, 7 Practical, 7 Weatherby, 7 Dakota. But you can get high quality dies, good brass, great bullets. It’s a Wildcat but several of us around that have messed with powders from H4831 to R33 and everything between.

The 7mm Practical was what sent me in the direction of my 7.21 Sage. My version of the 7-300. Mine has minimum case taper and a 35 degree shoulder.

Shoots a solid 1/2 MOA or better. I’ve only shot three shot groups seeing it’s a magnum I use for hunting. Also from past experience it won’t be easy on throats. So I don’t heat it up. It’s a 8 twist, 3 contour Schneider Barrel. Took my first game with it this last fall season. Two Mule deer, one at a bit over 400 and one at 847. Both were Bang Flops with the Hornady 180gr ELD-M @ 3183 FPS.

Shoots the 162gr ELD-X well.

300yards 3325 FPS / This was my top end. I backed it down a bit.



300 yards@ 3256 FPS. My fireforming loads shot extremely well & fast.



300 yards



180gr ELD 300 yards @ 3183 FPS

SMACK



First off, I have the patent on Grocery Bag Target
background.

Second, I reckon that accuracy is good enuff ?


Congrats, Good Rifle & GREAT shooting.

Jerry

I have a Sako 75 SS V in 7mm Rem mag. It has maybe 20 rounds down the tube from the previous owner. The Mag box is 3.75 , can I clean up the chamber with either a Practical, 7mm=300 win or the 7.21 Sage ?

Yes. All three reamers mentioned will clean the chamber right up and all three use a standard .300 Win Mag “Go” & “No” go gauge.

7.21 Sage Cartridge (Left)
7mm Magnum case (Right)

That is way too easy, so the barrel will not have to be setback or anything? If so do you have a gunsmith you can recommend?

Kampfeld Custom

Thanks

Barrel length???????

24.3 or .5 not sure

Good information. So, with any of the mentioned (7-300, mashburn,sage,Practical) except the Dakota, you are basically sizing a 300 Win Mag case and fire forming much like an AI. Am I correct or simplifying? Now how does one deal with the magazine box properly Never knocked one out. This is a down the road project for me but not too far out. Would be a 700 or clone action.

That might be something to ponder. Usually these big boys want a minimum of 26" tube to see real results. It's like making a 24" 7mm mag to a 24" 7 STW........ I know I had a friend that reamed one out. Very disappointing gains.

I have thought about that as well. I used to own one of these in 7mm STW and it had the 26" tube

Reaming one out....

Better thinking would be to cut off a neck length of barrel shank and then a re chamber. Reamer dia vs old chamber dia could be a miss fit, not to mention if the factory barrel is not machined with bore and chamber aligned. There will always be some run out, how much is a question. The gunsmith will need some latitude in cleaning up bore alignment with chamber mis alignment with the new chamber. This can be more work than chambering a new barrel.

Also, don't expect any accuracy guarantee.

Fotus, excessive freebore and throat dia allows a lot of gas blow by resulting in velocity loss, not to mention bore dia varies...reamers and throat geometry count.

I shoot a 7 STW with a Pac Nor 27" tube, 140g tipped tripple shock at 3650, tiny groups...550 is a chip shot. Barrel is twisted for 140-150g Noslers with 3750 fps being a max load with accuracy for the 140g C/T bullet. Obviously, I don't shoot long range, just do not like running deer. Same load with a 140g Nosler C/T bullet has never failed brother and I also....never on BIG Kansas deer that go over 300 lbs out to 550 yards. Kansas record white tails run over 400 lbs...we have not seen any of these.

Since good Winchester brass has disappeared for the 7 STW, I have designed a 7 Mashburn reamer and a 7 Practical That I hope to chamber this year in Brux barrels for use in Old blue bag winchester brass. I did not design a CIP spec reamer for RWS brass.

WELL that's just great ! I ought to 'smack' SMACK !!
Something else to drool over & I just happen to have a GOOD donor complete rifle. Chamber reaming is all I'd need.

thanks alot ! (sarcasm - grin)
A very interesting idea.


Thnx Jerry


ps: I need help. Anyone have Rifleanon's ph number?

Good info thanks. The 7mm rem looks tiny in my Sako V action. I have shot it very little since buying it in February but the previous owner who I know had no problem with it at all. I might need to look at a aftermarket barrel and I also have a SS 700 Mag in 257 laying around as well.

Out of complete curiosity and due to my addiction to tinkering and wildcat chambering. I decided to do the exact same 7.21 Sage concept but necked up to .338. Grant at JGS said my reamer should ship next week. I already have a factory Rem700 .338 Ultra and a Benchmark built .338 Edge (Which is spooky accurate) but I wanted to see if I could get similar gains as I did with the 7.21 Sage over the 7mm Magnum using the 300 Win mag case.

7.21 Sage cartridge (Left)
.338 Winchester Magnum case (Center)
On the right is a .300 Win Mag case with a .338 230gr ELD-X, when fire formed it will have the same 35 degree shoulder and case taper as the 7.21 Sage on the Left.

I’m looking forward to load development.

How long is the barrel on your rig and how heavy is it? Maybe it’s just me but the barrel looks like it’s loooooong!

Smack I can tell I DON’T need to hang with you.

I just thot I had a problem.

That’s too interesting.

Jerry

[/quote]

How long is the barrel on your rig and how heavy is it? Maybe it’s just me but the barrel looks like it’s loooooong!
[/quote]

28” 👍 3 contour Schneider. It’s not heavy. I hunt open country. We can take shots as long as a guy is capable of.








Columbia River in the bottom. BIG COUNTRY! Biggest California sheep on the planet. A friend here holds the SCI world record. 👍🙃👍

I’d like to see the results. What barrel length are you going to put that in?

I have extremely limited experience with the 7 Practical...a friend is into long range shooting, has one, and invited me out.Had no trouble keeping them on a 24 inch plate at just over 1400 yards...my personal best. We were going to go to a mile, but the weather closed in on us. Fun stuff!

In this day and age, I don’t know why one would choose a belted case for a wildcat when there are belt-less alternatives available.

Flamesuit on!!! :-))))

7mm-300PRC

Pass the 7-08,the 180 ELD and hold the Fluff.

Hint..............

I could really GAF about a big-assed 7 of any sort, or a .30 either,

...but that's really some sheep you have there! Major congrats on that one. Amazing.

I may acquiesce yet.

(5) rounds in the belly,killer brass abounds,barrels live forver and 2600fps is a breeze in a rather modest spout(21"). In my current atmosphere,it is supersonic to the 1765yd line.

Hint................

No flaming here.

ATST - What's to worry about in a 'belted' case?

I've been shooting them since the late 70s. When you learn to PFL size (like non belted cases) and DON'T attempt to headspace off the belt, you have very good case life.

I like long and slender VS short and FAT! I like the LOOKS of the 6mm Rem case better than the 243 case, et.al.

In over 40yrs of using belted cases I have not:

A. Caught the pox
B. Caught measles
C. Had hives
D. Had any STDs
E. Had ANY problems you can't encounter with beltless cases.

Now, if you like short actions, 1/2" shorter bolt throw, 1/2" shorter rifle length w/same barrel length, and 4 (FOUR) oz lighter weight
then you have all the advantages.

All of this stuff really boils down to Personal Preference. Just please yourself.

IF I listened to most things I've read here, I'd be changing Rifles, Cartridges, Powder, Bullets every week.

"Don't worry, BE Happy"

Jerry

Mechanical advantages,are not subjective...despite the volume/intensity of the Whine. Congratulations?!?

Hint.............

REDUX

"Don't Worry, Be Happy"


Jerry

Stupid ain't ever smart...no matter the bumper sticker.

Hint..................

Jerry

Imagination and Pretend..."soothe" many. Congratulations?!?

Hint.................

I’m still kicking it around. Bartlein 9.3 twist , #3, 29” blank. I’m leaning towards 26” but what does two more inches mean to 28” for a open country deer, Bear and elk rifle?

The 180gr ELD-M is a bad AZZ bullet.

So I "hear"...................(grin)

28” 👍 3 contour Schneider. It’s not heavy. I hunt open country. We can take shots as long as a guy is capable of.








Columbia River in the bottom. BIG COUNTRY! Biggest California sheep on the planet. A friend here holds the SCI world record. 👍🙃👍



[/quote]

Must be the 28” plus brake. I’m more accustomed to “no more than 26” and I’d skip the brake. A clear cut or pole line is as open as it gets here. Perhaps some “old growth” hardwoods might afford a longish poke although, some future travels will open things up. A bigger 7 will be in the works though just haven’t decided on the flavor yet. Done 7-08,7x57,280, 280 AI and still have all but one. I like every one of them too.

Schit scope,schit stock,schit mounting system and schit stock...too fhuqking funny!

Dime Store Cowboys are a fhuqking hoot,on their "realizations".

Hint...............

Should be a good performing round as far as hunting goes. Keep us posted.

Hoping Hornady will make a 7mm PRC a SAAMI standard. I'd jump.