Anyone own a 7mm 300 Win Mag?

[fmajor]

Still have not had time to fire form more then 20 cases for my 7mm Practical but my daughter did take it deer hunting and folded up two bucks in their tracks. 160 gr. Nosler Accu bonds.

Nice bucks!!!

It's good to see a stellar rifle and chambering do more than simple paper punching/steel bashing! What range/conditions were these fine animals taken at?

You must be (and should be) very proud of your daughter's appreciation for and participation in hunting and shooting. Unfortunately, my daughter has accepted a little too much influence from my wife's aversion to all things hunting/shooting.

 

[cockcroft]

Yes I am very proud of her and her older brother too. Both love to hunt and shoot. She has a custom 250 Ackley that she began hunting with but I think she wants her own 7mm Practical now. She is left handed as I am. Last years buck was taken with her 250AI. Her and her boyfriend are starting to get interested in LR shooting. She has a 243AI bench gun that I am re-chambering to
6.5-284 for her, need to get it done before this years clay pigeon matches start up.

Last year

 

[18echo]

Does anybody have load data for the 7-300WM using IMR 7828ssc and the Berger 180 VLD?

I know retumbo and H1000 are the preferred powders but both are like a unicorn, non-existent, and I just picked up 16lbs of 7828ssc because the burn rate is very close to H1000.

Like to know where I can start and max out at...

 

[chuckhammer]

Does anybody have load data for the 7-300WM using IMR 7828ssc and the Berger 180 VLD?

I know retumbo and H1000 are the preferred powders but both are like a unicorn, non-existent, and I just picked up 16lbs of 7828ssc because the burn rate is very close to H1000.

Like to know where I can start and max out at...

I ran a QuickLOAD calculation using the numbers I have for 7x300 case capacity in W-W Super brass (89 gr H2O). With a COL of 3.500" using a Berger 180 Hybrid I show a starting load of around 69.0 gr IMR 7828SSC for 55k psi and a max load of 73.0 gr for 65k psi.

For comparison with a 28" barrel, you end up with the same 3230 fps and 65k psi max pressure with either a 73 gr max load of 7828SSC or a 78 gr of max load of H1000. Difference is about 105% case fill with H1000 vs. 95% fill with 7828SSC.

This is according to QuickLOAD. Reality will be slightly different.

 

[Kiwi Nate]

Hi Guys, again I have not been following this thread all that much over the last couple of years so please excuse me if I cover the same old territory.

Several posts ago, a man asked about who he could get to do a basic rebarrel. Garou22 replied: "My Practical Is A 30 Inch Lilja 3 Groove Sendaro Contour Fluted With A Break" Then further on said: "Dave's 7Mm X 300 Win Mag Reamer Is Specifically Cut And Sized For..." He has mentioned two different cartridges in this post so I want to reset things straight for others coming in mid way into this length thread. Sorry garou22 if I have misunderstood your post in any way.

OK, first things first. The Mashburn is based on the .300 H&H, not the .300 Win Mag. The .300 Win Mag was not around when the Mashburn came along. Dimensions and forming processes are not the same as they are for the 7mm-300 WM or Practical.

Next- the 7mm Practical is not quite the same as the 7mm-300 Win Mag. Besides the steeper shoulder angle, when I designed the Practical, I found that the initial rifles could only be loaded a few times before the brass became tight with neck sizing, causing a need for custom FL dies which I wanted to avoid. So before I got any further ahead, I studied where the tight fit was occuring, then changed the dimensions and gave the Practical the shehane treatment, opening up the forward body dimensions / less taper. Providing the brass maintains a degree of spring back, this allows for continued neck sizing. This was my final 7mm Practical design.

The above being said, the body dimensions ( just behind the shoulder where the tight fit occurs) can easily be bumped with a .338 Win Mag or .300 Win Mag FL die if need be. The bottom of the case does not produce sticky extraction providing the basic guidelines for reaming are utilized, as given on our website.

The 7mm Practical is a no throat design, meaning that a separate throater is used to on each rifle. I designed the Practical this way so that the cartridge could be housed in long action rifles of various magazine lengths without having a negative effect on bullet jump. But there are limitations. The Howa / Weatherby Vanguard is the shortest long action the Practical can be housed in. The Ruger M77 for example, is too short. There are some folk who have asked PTG to create reamers with a specified lead rather than having their smith use a separate throat reamer as per my drawing. This can work out quite well providing the client does his math beforehand.

It pays to try and maintain a level of flexibility when selecting a preferred COAL so that if X bullet must be used in Lieu of Y bullet not being avaible due to supply problems, bullet jump or concentricity will not be a problem. The COAL's I have suggested for the Practical in a long magazine long action rifle are of this flexible nature.

The Practical is now used in New Zealand, U.S.A, Canada, New Caledonia and central Europe. There will soon be rifles in Australia and South Africa. The cartridge is employed for both long range hunting and competitive shooting. I am not sure whether I would want to use such a hot number for comp work but its nice to see the cartridge being put to use. I was hoping that many of the owners of 7mm Practical rifles would touch base with photos and such but alas, the Practical has grown very quickly in popularity and to some extent, taken on a life of its own.

Lastly, there are still folk concerned about basing a cartridge on a belted case design. In this instance, the belt is highly advantageous as it helps with one step fireforming. I have been able to shoot out to 1100 yards with FF loads in the Practical. However, for those who wish to use light fireforming loads, Trail Boss is the way to go.

Sorry to reiterate this stuff but there are probably guys like myself coming into this mid thread.

All the best guys and yes, that was a wonderful Buck. It is so important to pass hunting on to the next generation, even if such moments are brief. Great stuff.

 

[diriel]

@Kiwi Nate,

Dag Nabbit! Now you got me thinking about a 7mm Practical! Ugh...wife is going to kill me...

Thanks for the informative post,
Gary

 

[18echo]

I ran a QuickLOAD calculation using the numbers I have for 7x300 case capacity in W-W Super brass (89 gr H2O). With a COL of 3.500" using a Berger 180 Hybrid I show a starting load of around 69.0 gr IMR 7828SSC for 55k psi and a max load of 73.0 gr for 65k psi.

For comparisonand with with a 28" barrel, you end up with the same 3230 fps and 65k psi max pressure with either a 73 gr max load of 7828SSC or a 78 gr of max load of H1000. Difference is about 105% case fill with H1000 vs. 95% fill with 7828SSC.

This is according to QuickLOAD. Reality will be slightly different.

Chuck you rock, thanks so much for the info. Gradous has all my components and I'm just waiting for the call. It's a surgeon 300WM / 7-300WM switch-barrel, my 7-300 barrel is a 1-9 benchmark that is going to finish at 27". I'm hoping the 7828ssc will do it for both calibers as H1000 and Retumbo are impossible to find.

 

[chuckhammer]

Chuck you rock, thanks so much for the info. Gradous has all my components and I'm just waiting for the call. It's a surgeon 300WM / 7-300WM switch-barrel, my 7-300 barrel is a 1-9 benchmark that is going to finish at 27". I'm hoping the 7828ssc will do it for both calibers as H1000 and Retumbo are impossible to find.

No worries, happy to help.

That sounds like a fine rig you're building. I like your plan for a single powder for both cartridges from a logistics standpoint. H1000 would be about ideal but it IS a pain to find right now.

I've had good luck thus far with Reloader 33 in my 7mm Valkyrie. It's simply a 7-300WM with a 37 deg shoulder and reduced body taper. The result is an extra 4 gr H2O capacity, elimination of case growth, and (somewhat) reduced throat erosion. Anyway, RL-33 is well matched to this ~90 gr H2O case size class with a 180 gr 7mm bullet. I bet it also works well in 300WM with 215 or 230 Hybrids.

Nate,
Reading through your well-documented development of the 7mm Practical was the final push I needed to pursue my own, similar wildcat last year. Thanks for the learning and the inspiration.

 

[diverdon]

A lot of the answers to your questions are in the article link I provided. Perhaps you missed the link, here is again:
The 7mm Practical. A Practical Magnum.

As for Remington and Winchester getting it wrong. Things are never quite that black and white. When the 7mm Rem mag was in design phase, Remington engineers pretty much had two main contendors, Les Bowman's .338 Win mag necked down to 7mm or Warren Page's favorite, the 7mm Super Mashburn Magnum which is basically the 7mm-300 Win Mag, although in those days it would have been a blown out H&H. You have to remember that H1000 wasn't around back then so the 7mm-338 Win mag was probably a lot more efficient and effective, hence the adoption of the 7mm-338 as the 7mm Rem mag.

In modern times the market has been a bit tougher. It would not be easy to convince buyers that the 7mm-300 Win mag is the bees knees and a must have. The WSM's and RUM's are vastly different from the traditional belted mags so they get plenty of attention, the premise is based on sales way before ballistic performance.

I have just, 20 minutes ago, finished my third 7mm-300 for a client. This one is shooting groups of between .420" and .465", driving the 168gr VLD at 3212fps. I will leave it at that as the barrel has yet to be fully run in.

The article you link to is no longer at the link. Can you check the link? Thanks.

 

[Kiwi Nate]

Here you go...

7mm Practical:

http://www.ballisticstudies.com/Resources/Articles/The+7mm+Practical.++A+Practical+Magnum..html

Up one level shows the full index:
http://www.ballisticstudies.com/Knowledgebase.html

And the user submitted wound data base:
http://www.ballisticstudies.com/Knowledgebase/Wound+Database.html

I need to re-write the Practical Article again soon as it starts with the first version of the cartridge, then further down the page goes into the revision which makes for a wordy read with two sets of load data, the first set of data obsolete. I think it would be better if I trimmed the info down. A more succinct version is related in my last book.

 

[cockcroft]

When I ordered my 7mm Practical reamer from PTG I assumed it was the reamer Nate refers to as "his 7mm practical" reamer that does not have any free bore. My came with .188 free bore so be very specific when you order one so you get the free bore you want.
Mike

 

[Nimrod]

Does anyone still use the 7mm super mash. I have read that you can form brass from 300 win mag casings. It would be nice to start by reaming out a factory 24" barrel, and buy a longer one later.

Sorry, I just read this post. I am running a 7mm Mashburn Super. Mine is a Savage with a rechambered factory 7 RM barrel. I don't have a lot of data so far but I plan to ring it out pretty good this coming summer. My reamer was ground similar to Nate's 7MM Practical except mine has a short throat of .080 . With a separate throating reamer I can run it out wherever I want to. The Mashburn has a small but devoted following.

Bob

 

[Kiwi Nate]

If running a fixed lead reamer in the 7mm Practical, a good versatile bolt face to lead measurement would be 73.08mm or 2.877". This gives max COAL's of around 92mm or 3.622" with the A-Max and 92.2mm or 3.630" with the 190 grain Matrix. But again, it is important to check your magazine length to make sure it can handle cartridges of this length.

Putting the above into laymans terms, if approaching PTG or any reamer maker, you can set the throat length for a long magazine rifle (as opposed to the original no throat design) by including the statement: Please include freebore, bolt face to lead is to be 2.877". This comment can be placed during the order process.

Freebore is therefore .2043"

The .188" freebore is not far off this figure and not really enough to negatively effect velocity potential in a meaningful manner. Individual bore tolerances would have as much effect. So I think PTG have done OK with this estimate for Cockroft.

And as a final reminder, less freebore should be employed if for example, employing a Howa action which is right on the limit for minimum magazine length. Either use my no throat design and separate throat reamer or if using a reamer that features lead (what end users call the throat), set the bolt face to lead measurement at 2.836".

All of the measurements given here are with regard to allowing the shooter to seat close to the lands. Some folk may wish to adopt a little more bullet jump. For example, it is no great trick to get Berger bullets to shoot with 40 thou or more jump. In fact more often than not, the Berger bullets do much better with increased jump. If we take this a bit further and look the reamer Cockroft obtained, max COAL with the 168gr VLD is around 91.6mm or 3.606". The Howa / Vanguard (mag length 91mm or 3.582") feeds smoothly at a COAL of 90.2mm or 3.551" with a resulting bullet jump of 1.4mm or .055.

Really hope that makes sense and does not sound like a load of waffle.

 

[.284]

I did a 7-300 mag so as to use a 300 win mag body die if needed. I used ptg for the reamer and spec'd it to be used with a separate throating die. I sent some dummy rounds in with the build which allowed me to have the bullet (180 Berger) still in the neck when it touches the rifling and also let me chase the lands a bit if needed as the throat erodes. Built on a remy there is lots of room in the mag to do this. The bearing surface is long enough too that they can be seated in a bit if you want more jump. Lots of capacity so you're not crowding powder space if you jump them further.
So far I have only fire formed some nosler brass and have yet to get to the range with my first reloads. I wasn't sure if the fire forming was needed but I didn't want to find out later that new brass changed the pressure enough to affect the accuracy.