New 375 Sierra game king

[newlife457]

I checked Sierra's website and I see a 350g Matchking, but no 350g Gameking. Are you referring to the Matchking?

I know Berger is planning to introduce a new .375 bullet, but I don't know anything about the planned weight or bc.

I ordered some 300g Cutting Edge bullets for my .375. They have a similar bc to the Sierra Matchkings. I believe I should be able to push them to around 2700 or so from my H&H. The down side is that they will be expensive to shoot. They will definitely not be plinking bullets!

I have been thinking about the long range potential of my H&H and plan to experiment a bit to see what it can do. If the CE bullets work out, I hope to use Bergers or Sierras as a less expensive alternative for practice bullets.

Of course, if the CE bullets work out, I will also have to switch to long range glass for my .375. Right now, it is set up as a short to medium range smasher.

I shoot at elk and mule dear across Colorado canyons with a Win 70 SS in .375 H&H using 300 g gamekings at 2630 using 71gs H4895 and Federal 215 primers. I do use a full size KDF and the weapon is proported with 16 - 1/16" holes drilled on the upper axis of the front of the barrel. The gun weighs 11.7 lbs with a Harris bipod, Tasco 6-24 TR and Pachmeyer Decelerator. It is a prone gun. Have more to do to it. It needs a 2 stage trigger to try to get it to group less then the 1" that it does now and more load development needs to be done. I consider this weapon to be very close to the ultimate long range elk/mule deer gun for hunting in the snow out of Lake City or Glenwood Springs in the Uncompadre or on the Flattops Wilderness. The Tasco has a elevation turret etched to 825 years and it does range estimation also without a battery powered rangefinder. I do back it up with a G7 BR2 rangefinder for uphill/downhill work. I carry the weapon on a double shoulder biathlon sling in the middle of my back. I want to put in two mercury recoil suppressors in the butt stock of the synthetic stock to add weight and a hydraulic recoil pad. The gun still kicks more then I care for prone, but it is getting there. Recoil is my enemy for accurate long range shooting with this weapon. I have considered faster like making it a short throat .375 Weatherby. That would only really get me only 100fps more and more recoil. I am trying to get rid of recoil. I wanted a gun that would have 1000 fllbs remaining at least 800 yards. It has 1200 ftlbs at 1000 yards remaining.

 

[Cold Trigger Finger]

Getting 2700 fps from an H+H chamber is going to take a lot of barrel length. One of the improved rounds like the Whby, Ackley, Mash burn ect is a better bet. Less brass stretch also. My single farthest game shot was with the 375 HandH with the 300 gr TBBC High Energy factory ammo that chronographed just over 2700 fps at the muzzle. . Over 500 yards with a fixed 3x Leupold. . But I knew that rifle extremely well. This is one of my favorite calibers and cartridges. It doesn't suprise me that people are starting to " discover " it for long range now that high bc bullets are available for it. CEB has a 320 gr bullet that would really make it shine for all around use.

 

[benchracer]

Using RL-17, Norma brass, and 300 grain SGK's loaded to 3.785 COAL, my accuracy load came in at 80.0 g with a 2780 average for ten shots from a 25" barrel.

Based on my testing so far, the 300 grain CE's should do well over 2800 with the same powder charge, but I expect best accuracy to come in around 2800.

 

[newlife457]

Thank you for the hot load info.

FYI the CEB 320g bullet will not fit down in the mag on a .375 H@H, so it can only be the first round out of the gun and how do you deal with the different point of aim scope wise if the second bullet is either different or slower to accommodate a shorter COL?. You can't.

I am starting to seriously consider the Nosler Accubond. It has a higher BC than the 300g Gameking and Nosler seems to have good quality control on the bullet. The reason, I have always used Gamekings is because one, they are notoriously accurate and two the 300g Gameking is made expressly for the H@H. 3% antinomy added to the lead in the bullet. Hard bullet. My concern with the Accubond is that very thing. How will it hold up at 800 yards in running into a big elk's shoulder bone? I need to see so more actual usage from sites like this before I mess with the success I have had with the 300g Gameking at 2630 fps.

My rifle has a fullsize KDF and bunch of holes drilled in the top and sides of the barrel and a Decelerator and it still kinks more then I care for prone. I am considering a hydraulic recoil pad and two of the heaviest mercury recoil suppressors in the buttstock and maybe a smaller one in the forearm. I would be happier if the gun weighed 13 lbs. I carry it in a biathlon dual sling on my back so weight is not a problem, recoil is.

One other thing, does anyone have any experience with the actual accuracy of the .375 Weatherby with it's long throat? Or do I need to go with a short throat if I go that way? I am considering the Ackley Improved. I get 1" now and I think most of that could be mitigated with a better trigger (two stage) and more load development.

 

[Cold Trigger Finger]

Using RL-17, Norma brass, and 300 grain SGK's loaded to 3.785 COAL, my accuracy load came in at 80.0 g with a 2780 average for ten shots from a 25" barrel.

Based on my testing so far, the 300 grain CE's should do well over 2800 with the same powder charge, but I expect best accuracy to come in around 2800.

I really don't know what to say. That is totally unheard of velocity for an H+H. I did get that kind of velocity from a #1 that I had reamed to the Whby. But that was backing out primers.
I'm not doubting you I have just never seen that kind of velocity and I've owned and hunted more than 6 H+H chambered rifles.
However, I've never tried Rl 17 in the 375.
Wow!!

Is yours the H+H chamber? CZ 550 ?

.
You do realize that this is just about revolutionary kind of velocity. . Your beating the normal 270 gr velocity by 100 fps.

Again. I'm not doubting you but I've loaded a lot of 3+ six bit ammo and killed lots of stuff with the round. Any more info you could provide would be much appreciated. .
A 300 gr CEB at 2800 fps with good accuracy from an H+H chamber. , that's a 1 load. 15' on a brown bear to 1,000 yard plus deer load. All in 1 load. And having everything needed in 1 rifle and round.

 

[Cold Trigger Finger]

That's over 5,000 ft lbs muzzle energy. . That's just amazing!!!

 

[benchracer]

I really don't know what to say. That is totally unheard of velocity for an H+H. I did get that kind of velocity from a #1 that I had reamed to the Whby. But that was backing out primers.
I'm not doubting you I have just never seen that kind of velocity and I've owned and hunted more than 6 H+H chambered rifles.
However, I've never tried Rl 17 in the 375.
Wow!!

Is yours the H+H chamber? CZ 550 ?

.
You do realize that this is just about revolutionary kind of velocity. . Your beating the normal 270 gr velocity by 100 fps.

Again. I'm not doubting you but I've loaded a lot of 3+ six bit ammo and killed lots of stuff with the round. Any more info you could provide would be much appreciated. .
A 300 gr CEB at 2800 fps with good accuracy from an H+H chamber. , that's a 1 load. 15' on a brown bear to 1,000 yard plus deer load. All in 1 load. And having everything needed in 1 rifle and round.

I, too, think it will make for an ideal load for most things when I am finished with development. The CEB produces much longer OAL's (4"+) than conventional bullets like the Sierra do. Even in a CZ550 (which is what I have), that means one laying on the feed ramp and one in the chamber, at best. If the ability to fully function as a repeater is important, conventional bullets are a better choice.

You can track the development I did here. This thread should answer a lot of your questions:

http://www.longrangehunting.com/forums/f28/375-h-h-300g-bullets-best-velocity-106504/

The 300 grain SGK load is running on the edge of pressure limits. With the MTH, I expect to be able to actually back my load off slightly and still reach 2800 or so, which is where I expect to see best accuracy.

 

[Cold Trigger Finger]

Thanks for getting back to me on this. I'll read your thread with great interest. . Its kinda frustrating in a way. I had this wildcat all dreamed up and now I may just go back to what I was shooting almost 30 years ago.
I would be willing to give up 100 fps for just magazine feeding all rounds tho. And I'm wondering about using the 375Ruger .

 

[benchracer]

The COAL required for the MTH's isn't dictated by velocity. It is dictated by the bore rider/driving band design. The 300 grain MTH has a recommended COAL of case length (2.850 in the H&H) + 1.141", which takes you to 3.991 COAL.

CE says that the bullet can be seated deeper by up to half the length of the neck. In a CZ 550, that could get you below 3.900, which may allow the rounds to be fed from the magazine. If the MTH's shoot well seated like that, you are golden. If not, you have to either live with less accuracy or single feeding. Pick your poison. In the modified 30-06 actions that most other manufacturers use to house the H&H, the MTH's are going to be a single shot proposition.