The 7-300wm is alive.

[IdahoCTD]

I built it a few weeks ago and finally got to shoot it today. I loaded 2 rounds of H-1000 at 70grs to get it sighted in and then shot a ladder with 71-75grs. 72-75grs made one big hole that was about .55". Then I shot a 3 shot group with 73grs of H-1000 and 162 Amax's. It went .342" with a velocity of 3113, 3109, and 3106. I just guessed on a load and it looks like I need load some more at 74 and 75 to try for a group. 75grs went 3181fps in the ladder test and only had slight flattening of the primers.

Well I can't post pictures again because of the attachment quota.

I forgot the spec's of the rifle. It's a Remington 700 SS action with a #5 contour Schneider 5P 9 twist barrel cut 27" long (I couldn't decide between 26" and 28" so I split the difference). Right now it's in a wood Rem. 40x stock but will end up in a light weight High Tech stock. Hopefully the weight will be around 9lbs scoped.

 

[FOTIS]

Sounds sharp!

My 7 mags always bottomed out at 72.5 gr H1000 with the 160's

 

[DrMike]

That does sound fascinating; it is assuredly out of the ordinary.

 

[IdahoCTD]

The nice thing is it functions through a standard magazine with the bullets seat out where they should be. That is where a 7STW has trouble. With the extended mag. boxes a 7STW is better then it use to be but still not great. I have 2 7STW's and have owned 5 or 6 total. Having to seat the bullets deep always bugged me. I also have a old 7-300wm I had built for me years ago on a Mark X mauser action with a douglas barrel. I shot a lot of stuff with that gun. So I just built a newer better version. It's also quite similar in performance to the new 7LRM Gunwerks is building. It's based on a modified .375 Ruger case.

 

[remingtonman_25_06]

Nice!!!

I really like the idea of the 7-300 mag for that reason as well. The case is short enough to be able seat bullets out and still hit the lands and function in the mag, something the full length mags cannot do without a mag box extension.

3100 isn't to bad with a 27" if that's where she shoots. I would be going with a 28" in hopes of the 3200 mark accurately.

Right now I'm only getting 2875fps with 162 amax accurately from a 26" model 70 7 Rem mag. I could go for another 300fps with this bullet accurately.

 

[IdahoCTD]

2875fps is pretty slow from a 7 mag.

I think it will shoot faster than 3100fps but if it doesn't it doesn't. I'll load some at 75 and 76grs of H-1000 to see what it does. If I'm not impressed I'll go back to the 73gr load or try some Retumbo. It's a fairly light gun so I'm not going to expect miracles at super long range but I'd like to see it shoot decent to 800yds (less than 1 MOA consistently and would prefer 3/4 or 1/2MOA). It's not too often I "HAVE" to shoot further then that.

Most people are shooting 180gr Bergers from 3075 to 3175fps so it should shoot the Amax's 3150 to 3200 fairly easily. This guy build one with a steeper shoulder and that is what he got too.

http://www.ballisticstudies.com/Resourc ... gnum..html

 

[CMBTshooter]

This sounds like an awesome project. I wonder how much barrel life you will get.

 

[Desert Fox]

My 7WSM will shoot the 180 grain Berger at over 3,000 fps using Reloader 25. But then again, my barrel is 30". The WSM is very efficient cartridge.

 

[IdahoCTD]

Most guys with the 7-300wm are getting 3150-3175 with 180's and 28" barrels. If the Amax's shoot I have no reason to use anything else though. This is a rather light hunting gun that will be used out to 800yds or so.

 

[super-7]

This is the one version I am considering building of the 300-7 . But then I shot the donor. why why why.





The 7mm Practical


The design premise for my version of the 7mm-.300 Win Mag was to obtain maximum power from the 7mm bore without excessive wear, suitable for the volume of shooting (practice and hunting) I prefer from a long range rig (approximately 12 shots per week on average). The cartridge is intended to be used for hunting light to medium weight game from point blank, out to true long range distances. The case capacity is what I consider to be optimum for a balance of efficiency versus effective power at extended ranges.

The 7mm Practical has other user friendly advantages. These include a long neck, longer than is found on the Win and Rem magnums, both old and new designs from the 2.5" magnums through to the WSM/RUM’s, many have a neck length of up to 6.8mm at best. The longer neck helps bullet to bore alignment immensely. Rather than trim the brass, for the first several firings, the brass is allowed to grow until it reaches the desired length (see notes below).

There is no need for special dies or special operations when reloading for the Practical. Simply use a standard 7mm neck die and 7mm Rem Mag seating die and get straight into maximum performance. Bullet jump is dictated by the separate throat reamer and each rifle should have its throat cut to suit its magazine box thereby minimizing bullet jump.

The Practical has a 30 degree shoulder, duplicating the WSM/RUM shoulder angle as opposed to the parent .300 Win Mag which has a shoulder angle of 25 degrees. The idea behind the change in shoulder was to assist positive head spacing at the shoulder with hand loads and to some extent, it was hoped that it would encourage case neck growth based on my experience with the RUM and WSM’s which seem to display rapid neck growth. To be honest, I do not know if the change in shoulder angle actually made any difference. It’s certainly not a point worth pushing.

The Practical is also intended to make use of an easily sourced parent case. The belted case is also easy for gunsmiths to work with, without need of custom head spacing gauges. The Smith can use standard 7mm Rem mag go and no go gauges to check fit. In this way, the fire forming load utilizes the belt and gives It (for once) a useful purpose while consecutive loads are head spaced at the shoulder for optimum accuracy.

Above all, the Practical was designed to do what its name suggests, to provide a simple, practical cartridge for precision long range hunting. Don’t get me wrong, the Practical is in no way as efficient as something like the excellent .308 Winchester. If I had my way, it would be mandatory for every licensed western hunter to own a .308, the arms officer would give you one after he or she ticked the last box. For 50 cents, you could upsize to the .30-06. No, the Practical is relevant to the pursuit of optimum magnum performance.

Pacific Tool and gauge made the reamer for the Practical as well as the separate throat reamer. The reamer was perfect, as can be expected from PTG and the turn around time was incredibly fast, certainly beyond expectation. True-Flite NZ Ltd (Gisborne, New Zealand) blueprinted the M700 action I used as the platform for the build and fitted a button rifled barrel of their manufacture along with a PTG recoil lug and Barnard extractor. The stainless steel barrel has a twist rate of 1:9”. I also used this opportunity to trial True-Flite’s new 6 groove 7mm barrel which will eventually be offered along with the current 4 groove canted land design. Three weeks later, I was lucky enough to have a client want to try the Practical using True-Flite’s 4 groove canted land barrel. Results were as can be expected from True-Flite, simply outstanding for both rifles.






The 7mm Practical
Max case length 2.657 (67.5mm)
Trim cases to 2.645 (67.2mm)
Neck length for the practical when trimmed is .289 (7.3mm). Several shots are required before cases will grow to the ideal 2.645 length.




This is copied and pasted from Nathan Kress's web site.

 

[FOTIS]

There are a ton of game being taken on you tube with the 7mm Practical. Especially LR goat kills in New Zealand. Very impressive.

 

[SJB358]

My 7WSM will shoot the 180 grain Berger at over 3,000 fps using Reloader 25. But then again, my barrel is 30". The WSM is very efficient cartridge.

I love those pictures DF and your right, I run 160's at 3100 in my 24" barreled Model 70 with RL22... Your results have always wanted to make me try 25 though.

Nathan, your 7-300 sounds pretty cool. Thinking it is like the 7mm Mashburn Super?

 

[FOTIS]

Those are some amazing speeds for a 7mm WSM for sure. 30" tube and all.

 

[SJB358]

Cartridge : 7 mm WSM
Bullet : .284, 180, Berger BTHP #28404
Useable Case Capaci: 71.031 grain H2O = 4.612 cm³
Cartridge O.A.L. L6: 2.860 inch = 72.64 mm
Barrel Length : 30.0 inch = 762.0 mm
Powder : Alliant Reloder-25

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-10.0 93 60.37 2796 3125 44953 8999 100.0 1.634
-09.0 94 61.04 2823 3186 46497 9047 100.0 1.609
-08.0 95 61.71 2850 3247 48097 9095 100.0 1.585
-07.0 96 62.38 2877 3309 49754 9141 100.0 1.562
-06.0 97 63.06 2904 3371 51471 9187 100.0 1.539
-05.0 98 63.73 2931 3433 53251 9233 100.0 1.516
-04.0 99 64.40 2957 3496 55099 9277 100.0 1.494 ! Near Maximum !
-03.0 100 65.07 2984 3559 57016 9321 100.0 1.472 ! Near Maximum !
-02.0 101 65.74 3010 3622 59001 9364 100.0 1.451 ! Near Maximum !
-01.0 102 66.41 3036 3685 61064 9406 100.0 1.430 ! Near Maximum !
+00.0 103 67.08 3063 3749 63204 9448 100.0 1.410 !DANGEROUS LOAD-DO NOT USE!
+01.0 104 67.75 3089 3813 65419 9489 100.0 1.389 !DANGEROUS LOAD-DO NOT USE!
+02.0 105 68.42 3115 3877 67705 9529 100.0 1.370 !DANGEROUS LOAD-DO NOT USE!
+03.0 106 69.09 3141 3942 70070 9568 100.0 1.350 !DANGEROUS LOAD-DO NOT USE!
+04.0 107 69.76 3166 4007 72518 9606 100.0 1.331 !DANGEROUS LOAD-DO NOT USE!
+05.0 108 70.43 3192 4073 75055 9644 100.0 1.313 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 103 67.08 3153 3973 77446 9124 100.0 1.311 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 103 67.08 2924 3417 50103 9926 100.0 1.543


I dig that little 7.. It grows on me everytime I shoot it. Very good cartridge. Wished there were more cases available..

 

[SJB358]

Those are some amazing speeds for a 7mm WSM for sure. 30" tube and all.

What case do you use to form the 7mm Mashburn Mag?

 

[IdahoCTD]

It's based off of the .300 H&H Scotty.

 

[SJB358]

How would you make it now? 300 Win Mag?

 

[Oldtrader3]

The Washburn Magnum was made from a shortened .300 H&H case.

 

[IdahoCTD]

The OAL is longer on the Mashburn then the .300wm and the neck is quite a bit longer. So yeah you could use .300wm but you'd end up with a shorter neck. It's 2.635" for the Mashburn and 2.62" for the .300wm.

 

[SJB358]

Got ya. Makes sense, thanks for the intel.

I have a 338 Win Mag at the gunsmiths and I am in a dilemma as to what to do with it. Thought a 358 Norma, but I am not sure it'll do much my 338 will. Gotta put some thought in it. I have a couple of GREAT 7's too..