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Anyone own a 7mm 300 Win Mag?

 
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  #78  
Old 10-22-2010, 06:01 AM
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Re: Anyone own a 7mm 300 Win Mag?

I think one factor you need to bare in mind is- design goals. Most people who opt for the 7mm-300 do so because they want magnum power, but also want to plink/shoot a lot which in a larger capacity cartridge, is undesirable due to excessive wear. Even the 7mm-300 is pushing the limits but the people who choose this cartridge, have an idea of what to expect. On the other hand, there are folk on this forum who absolutely love the STW and RUM. They also know what to expect, strengths, limitations- they work to the strengths of their pet cartridges.

The STW and RUM get the very last few fps out of the sevens via freebore. You could actually do the same with the 7mm-300 as there is plenty of powder space. With .400" freebore, velocities are much the same accross the board. To really understand just how relevent this is, have a look at the 7mm Weatherby. The case is much the same size as the 7mm Rem Mag, but it uses freebore, allowing it to drive 160 grain bullets at 3200fps. Weatherby actually go a step further than most, utilizing a 1:10 twist rate to minimize any yaw created by the freebore/ loss of bullet to bore concentricity. Its quite a cunning design.

The other night I pumped 3 rounds through my 7mm-300 as fast as I could work the bolt, I needed goats for dog tucker. I located a mob, shot the first animal all quite like but the next two shots had to be taken quick before the mob escaped into the bush. My .308 culling rifle is having a birthday at the moment so its out of action and I am using the big seven on a week to week basis. Pumping rounds out fast like that is what killed my last 7mm RUM. So, there are many things to consider when comparing cartridges.
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  #79  
Old 10-22-2010, 07:57 AM
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Join Date: Feb 2007
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Re: Anyone own a 7mm 300 Win Mag?

Quote:
Originally Posted by SidTheKidd View Post
Broz,
Got a couple more questions on the 7mm-300 for you. What sorta groups were you guys seeing at 100 yrds with the berger? Also was the gun throated specifically for the VLD bullets? Also if you remember, how far off the lands were the VLDs when they shot the best? Where you seeing alot of runout with the RM brass?(You are right, this is what I am using.)

I guess I ask because, I was talking to a fella today who has shot alot of Bergers and swears that they will only shoot on or in the lands if the throat is not reamed for them.
Sid, I don't hardly ever shoot groups at 100. I prefer 200 or more as I feel it gives the bullet time to stabilize. I will take a .5 moa group at 300 to a one hole group at 100 any day. Just my personal preferance. That said this rifle will shoot 180 bergers into 1 1/2" at 300 on a very regular basis, and some times better.

The gun was not throated specially for bergers, but it has a long throat, this worked out well. I had the bullets close to the lands at first, but decided to back them in to see how they shoot if they would fit in the box. That came out to be .115" off the lands. That is where there are now and shoot awesome. So I don't feel anyone can say that the bergers have to be on the lands. I have seen them shoot in many rifles I own from .005" in the lands, to this rifle at .115" off. I would just use the Berger seating method and see what your rifle likes.

We were not seeing a terable amount of run out with the RP brass, but the brass was old and I am very fond of RWS and Lapua brass for the 300's. So we changed to new RWS brass. After the first firing we did see noticably less run out, probably .002~.003" less on average.

I am not suprised you are considering a little less powder charge and I doubt if you back off a grain if it will be a negative affect on accuracy. Please remember if you ever go to RWS brass you will need to back off probably 4 gr but I feel you will see very close to the same velocity as you are now.

Hope this helps.

Jeff
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  #80  
Old 10-22-2010, 09:55 AM
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Join Date: Sep 2009
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Posts: 657
Re: Anyone own a 7mm 300 Win Mag?

Kiwi nate nate thank you for your replies. As I stated I am learning about this and you have answered my questions. I appreciate your patience. I had heard that weaterby uses a lot of freebore I guess I didnt consider or realize that about the rum and stw. I was considering building a 338 edge or 338 RUM because I had hearn that barrel life was terrible with the 7 RUM, so this gives me another option to think about. I am also looking to build the rifle as a long range hunting/plinking rifle , gotta practice to get good right. This 7-300 with the wildcats actually better ballitics than the 338 Edge/Rum, it gives up Ft lbs but still has about 1600 at 1000. So Broz I think I'm ready to un hijack your thread now, sorry. I appreciate the help advice and patience.
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  #81  
Old 10-22-2010, 03:35 PM
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Location: Taranaki New Zealand
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Re: Anyone own a 7mm 300 Win Mag?

No problems pyroducksx3, you are welcome.

You can see there is a slight difference between my load data and Broz's 3174fps. This will be due to the freebore in Broz's rifle. From what Broz has described, freebore in his rifle is similar, perhaps identical to the .308 Winchester when utilized in a magazine fed action. Its certainly not excessive.

Shot this yesterday, same freebore as Broz's rifle. Its a Howa I tricked up a couple of years back which has come in for a birthday:

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  #82  
Old 10-25-2010, 04:37 PM
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Join Date: Sep 2009
Location: Washington
Posts: 657
Re: Anyone own a 7mm 300 Win Mag?

Well the more I research everything it looks like this 7x300 WM will do everything the stw will do, possibly even better. It appears the 7 stw has more case capasity but is not really able to take advantage of it, or make any significant gains with it compared to the 7x300. It appears to me that the 7x300 is more effecient and makes up for it slightly smaller case capacity and gives up nothing to the STW and maybe only +/- 150 fps to the 7 RUM. Plus I like that I can get 300 WM brass from anyone ie nosler, norma, winchester compared to the stw only from remington and nosler. Is anybody seeing flaws in what I'm finding thinking, thanks.
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  #83  
Old 10-25-2010, 05:27 PM
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Join Date: Nov 2008
Posts: 123
Re: Anyone own a 7mm 300 Win Mag?

Quote:
Originally Posted by Broz View Post
Sid, I don't hardly ever shoot groups at 100. I prefer 200 or more as I feel it gives the bullet time to stabilize. I will take a .5 moa group at 300 to a one hole group at 100 any day. Just my personal preferance. That said this rifle will shoot 180 bergers into 1 1/2" at 300 on a very regular basis, and some times better.

The gun was not throated specially for bergers, but it has a long throat, this worked out well. I had the bullets close to the lands at first, but decided to back them in to see how they shoot if they would fit in the box. That came out to be .115" off the lands. That is where there are now and shoot awesome. So I don't feel anyone can say that the bergers have to be on the lands. I have seen them shoot in many rifles I own from .005" in the lands, to this rifle at .115" off. I would just use the Berger seating method and see what your rifle likes.

We were not seeing a terable amount of run out with the RP brass, but the brass was old and I am very fond of RWS and Lapua brass for the 300's. So we changed to new RWS brass. After the first firing we did see noticably less run out, probably .002~.003" less on average.

I am not suprised you are considering a little less powder charge and I doubt if you back off a grain if it will be a negative affect on accuracy. Please remember if you ever go to RWS brass you will need to back off probably 4 gr but I feel you will see very close to the same velocity as you are now.

Hope this helps.

Jeff
Yeah I will keep that in mind Broz,
Where were you finding that RWS brass? I have googled it and cant find the stuff. I guess I was asking about the seating depth because I had the best results so far with the 180 VLD's at .083 off. I am going to lower the charge another .2 an take them in and out .002 to see what happens. I hope I can get some groups closer to a quarter. Maybe I will try grouping out further too. That is something I have been meaning so try too..Thanks for the info again.
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  #84  
Old 11-19-2010, 11:38 PM
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Re: Anyone own a 7mm 300 Win Mag?

What a wealth of info you guys have here! I really appreciate everyone sharing such insight and experience. THANKS!

I got into this thread and went off the deep end....just so happens I found out my ole 7Remmy was shot out for the first 2.5 inches! And the same day I see someone had a brand new 7RM take off bbl. for sale cheap. Voila! New toy ordered. Smith has the old rifle and the new bbl. awaiting arrival of the 7/300 reamer. Meanwhile, I go out and get some new Winchester 300WM brass so as to get ready for the new toy.

Here's my dilemma:
I ran 6 brass thru my7RM neck die and did not use any lube (never did before) and collapsed one case and had a bulge on another that REALLY shortened up the brass. SO, I figgered I'd anneal the rest of the batch before anymore sizing. And I lightly lubed the outside of the necks. Lost 15 more to bulges & collapse!??

Also, the brass is very short after sizing. Of the 33 left, 18 are under 2.610 (Most are under 2.60) and the longest was 2.617. ???? Aargggh.....

My questions:
Anyone have any input as to technique, what I'm doing wrong, what I SHOULD do right, or any other instructions w/ regard to brass prep? ALL ideas, input is appreciated. I've been reloading for 25+ yrs. but am a novice at this wildcat stuff & am always willing to learn new things.

I asked my smith to make a set of dies w/ the reamer for the build. IF he is unable to do so, any leads on how to get dies from a commercial source?Do you guys just use a 7RM neck die to size and/or 300WM for a FLS w/ a 7mm stem? How about a seater die? IF you don't have a set of 7/300 dies, how do you do operate?
(Speaking of that, how would you get a few loaded rounds to fireform in order to send cases to have them built).

Any suggestions on the remaing brass I have prepped? I can't trim/true up the mouths on the shorts ones and I THINK there may be a slight bulge on one side of a few of them. Would fireforming iron out this problem, or result in a "Kaboom"?

LOL...STARTED to call the smith and just tell him to leave it 7RM, buth then the stubborness in my showed up and NOW it's a challenge! One that I'm sure I can meet by using all the wealth of help on this forum.

Hey, guys, thanks in advance for all your help! Take care.
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