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Anyone own a 7mm 300 Win Mag?

 
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  #71  
Old 10-21-2010, 01:26 PM
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Re: Anyone own a 7mm 300 Win Mag?

So here's what I think I understand..... the 300 win mag has a much larger case capacitycompared to the 300wsm, which is why I cant seem to find the supporting data of the 7mm wsm reaching these velocites. Also Im not sure how much difference it makes but if it appears it two bullets ofthe same weight in close diameters are pushed by the same powder charge , the smaller diameter willgo faster? ie .284 vs .308, so a 77 gr charge of H-1000 will push the 150 gr .284 faster than a 77 gr charge of H-1000 of a 150 gr .308. I assume this is because the .284 develops higher pressue? Also in these magnums 4" barrel length can account for as much or more than 200 fps. What really throws me is how say the 7-300 win mag using 79 gr of H-1000 in a 28" barrel can push the same bullet faster than a 7RUM using a 26" barrel using 87 gr of H-1000. as stated earlier they have a 7-300 wm with a 28" barrel using 79 gr of H-1000 pushing a 162 gr amax at a velocity of 3340 fps. Compare that the hornady manual the 7 RUM with a 26" barrel using a charge of 87.3 of H-1000 pushing a 162 gr amax to a velocity of only 3100 fps. Is this just the efficiency of the cartridge? If so somebody ie Remington, winchester missed the boat and should have made this a factory round.
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  #72  
Old 10-21-2010, 11:59 PM
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Re: Anyone own a 7mm 300 Win Mag?

Well no replys? again Im not attacking anyone. I just dont understand and when I dont understand I ask question and because of my lack of expierence I interpret data. So does any one know what a 7-300 WM would push a 200 gr wilcat ULD? If it could get 2900 fps it would be in a pretty impressive performer!
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  #73  
Old 10-22-2010, 12:57 AM
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Re: Anyone own a 7mm 300 Win Mag?

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.

Last edited by Teh Fixer; 01-11-2014 at 07:43 AM. Reason: fixed broken link
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  #74  
Old 10-22-2010, 02:03 AM
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Re: Anyone own a 7mm 300 Win Mag?

Kiwi Nate thank you for the reply it does answer some of my questions. Do happen to know what the 7-300 would push a 200 gr wildcat at Im guessing 2900-3000 but not sure. Thank you
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  #75  
Old 10-22-2010, 02:05 AM
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Re: Anyone own a 7mm 300 Win Mag?

Yes, you are right on the money. 2900fps and up to 2950 as a near max load.
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  #76  
Old 10-22-2010, 02:19 AM
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Re: Anyone own a 7mm 300 Win Mag?

Kiwi nate I just looked at the 7 STW and it case capasity is even greater than the 7-300 is it correct to assume that it will be capable of producing even higher velocities or does this extra case length not produce the effeciency of the 7-300? It seems to me the 7-300 is just slightly longer than the 7 rem mag with all other dimensions the same and the 7 stw is longer than the 7-300 with all other dimensions the same. Which to me means the stw would be able to match or beat the RUM but looking at the hornady manual the 7 stw using a 162 amz with 78 grains of H-1000 it produces a velocity of only 3150 with a 26" barrel so add the 35 per inch of barrel and we end up with 3240. What you have found is that the 7-300 using 77 gr gets you 3330. Seems that the 7-300 achieves the optimum case capasity for the 7mm and that you really dont gain much going bigger ie the stw, RUM is this a fair assumtion? Thank you again.
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  #77  
Old 10-22-2010, 05:30 AM
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Re: Anyone own a 7mm 300 Win Mag?

As I wrote in the article, the STW is reliant on freebore. This can be difficult for people to understand at first so take your time to think about what this implies. I have 40 thou jump in my 7mm-300. The STW has 400 thou- nearly a half inch bullet jump. It needs this as a pressure release valve. This creates its own set of problems. Again, please refer to the article and read it carefully.

If things were as simple as case capacity equals velocity, we could simply neck down the 50bmg to 7mm or .30 cal and run high BC bullets at 5000fps. But what would really happen if we necked the 50bmg to say 7mm? Well, the action or barrel would blow to pieces because the gas would not be able to escape through the barrel relative to its expansion. In other words, the .50bmg case has the potential to yield X amount of energy over Y amount of time while a 7mm bore has only Z amount of potential to vent this energy. Hell I hope that makes sense to someone- LOL.
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