375 H&H for long range

[Cold Trigger Finger]

I was looking around on Midway and they have down to 300 gr CEB's in stock. Not that bad a price either. I would like to build a 378 Weatherby some day. I don't need one but it would be great for an educated brown bear. With the CEB bullets its long range capabilities could be utilized.;
Those 300 grainers have a G1 BC of .75 .

 

[benchracer]

To maximize the 350 SMK out of the H£H you will need a tighter twist, like 1 in 10.

I'm not sure where this idea comes from. Sierra has 12" TWIST BBLS ONLY printed right on the box that the 350g SMK's come in. If you measure the bullet and plug the information into any twist calculator, it easily stabilizes in a 12 twist. Moreover, I have actually fired this bullet from a 12 twist .375 H&H at between 2300 and 2400 fps and it stabilizes from my rifle just fine.

A 10 twist will not hurt anything, but is not needed to stabilize a 350g bullet from an H&H.

 

[Cold Trigger Finger]

That's good to know! Thanks .
These long range 375 bullets have come out since I had my last 375 . They make the round even more speaking. Well, the 375 Whby any way.

 

[dig]

I'm not sure where this idea comes from. Sierra has 12" TWIST BBLS ONLY printed right on the box that the 350g SMK's come in. If you measure the bullet and plug the information into any twist calculator, it easily stabilizes in a 12 twist. Moreover, I have actually fired this bullet from a 12 twist .375 H&H at between 2300 and 2400 fps and it stabilizes from my rifle just fine.

A 10 twist will not hurt anything, but is not needed to stabilize a 350g bullet from an H&H.

I talked with the Sierra line about this as I was getting flyers in an older 375 1/12 They indicated that velocity (increase) helps stabilize the 350 grn. I have had very mixed results in the 2400 area out if a 1/12. I believe this weight is on the edge.

 

[Cold Trigger Finger]

At 2400 fps it probably is. With the H+H 300 gr bullets are about as heavy as I would go. As there are some very good 300 ft LR bullets I would stick with them. The 375 Rum should be able to send the 350 s fast enough to get good results.

 

[benchracer]

A .375 H&H on a full magnum length action, such as a CZ 550, will allow you to load to OAL's of 4"+. I am getting 2600+ fps with 350g SMK's and RL-22 from a 25" barrel. Though I haven't tried it yet, I would expect similar performance from IMR 7828 SSC. A Ruger #1 might also allow something similar to be done.

It doesn't appear to me that much experimentation has been done with the H&H for long range work. I have been tinkering with mine off and on for the past 18 months or so and am finding out that most existing information leaves a lot to be desired. The latest version of Quickload and a Magnetospeed chronograph have been very useful to me in developing my own data for 300g and 350g bullets.

There are a lot of misconceptions and outright untruths out there when it comes to the .375's and their capabilities.

ETA: If you are working with an action that limits you to 3.6" ish OAL's, RL-17 is the ticket with 300g bullets.

 

[Cold Trigger Finger]

A .375 H&H on a full magnum length action, such as a CZ 550, will allow you to load to OAL's of 4"+. I am getting 2600+ fps with 350g SMK's and RL-22 from a 25" barrel. Though I haven't tried it yet, I would expect similar performance from IMR 7828 SSC. A Ruger #1 might also allow something similar to be done.

It doesn't appear to me that much experimentation has been done with the H&H for long range work. I have been tinkering with mine off and on for the past 18 months or so and am finding out that most existing information leaves a lot to be desired. The latest version of Quickload and a Magnetospeed chronograph have been very useful to me in developing my own data for 300g and 350g bullets.



Your getting 2600 fps with the (350). ????????
That's pretty fast 416 Rem velocities with a 350 .
I've had several CZ 550 s, did you put a longer mag box in yours??
Are you using the factory barrel? If so are you using the foreend/ under barrel recoil lug? Do you still have the front sight barrel band on?
What kind of groups are you getting.
With my last 375 H+H, a stainless Montana action and barrel that I had to re cut the barrel threads myself with files. And screw it on myself. I got 2700 fps with the 300 gr Federal High Energy, Trophy Bonded BearClaw factory load. It was very accurate in that rifle. The barrel was 23" . Made the longest game shot of my life with that rifle/ load combo

 

[benchracer]

My CZ 550 is in its original configuration. The barrel band front sight, underbarrel recoil lug and magazine box are unaltered. With an OAL of 4.040", the 350g SMK loads are a single feed proposition. Given their long range potential, I am fine with that. I have been working mainly with 300g bullets, so I haven't gotten to accuracy testing with the 350's yet. So far, I have only done workups intended to establish pressure and velocity limits with the 350g SMK. Accuracy work is yet to come. I need to have some bedding work done on my rifle before I continue my testing (I noticed yesterday that the barrel is contacting the forearm).

With 300g SGK's and RL-17 loaded to 3.785" (which WILL feed from the magazine of my CZ 550), the 10 shot average velocity came in at 2780. That load grouped into 1.1" @ 100 yards (not bad for a rifle with bedding issues) and should have a trajectory very similar to .308 175g SMK match ammo. This load shot without pressure signs at 75* air temps, but gave me sticky bolt lift at 85*, so it is on the ragged edge of pressure limits. I would not be afraid to use it during fall hunting season in the states, but I wouldn't take it to Africa.

I had previously done pressure and velocity runups with the 350g SMK and H4350, RL-17, and H4831. I was getting max velocities of 2400, 2435, and 2300 respectively. With RL-17, the combination acted like it wanted a slower powder. But, the lower velocity obtained with H4831 appeared to suggest that slower powders wouldn't work.

After buying Quickload, I took some case volume measurements and started looking for answers to my questions. Quickload suggested that RL-22 and IMR 7828 SSC would produce the best velocities with the 350g SMK loaded long in the 375 H&H. Quickload predicted 2550 fps from my rifle. Actual shooting with 85* air temps produced velocities of 2601 to 2648 fps with my max loads without pressure signs of any kind. If I can get these bullets to shoot, I may forget all about the 300g bullets.

 

[AFRIFLEMAN]

If you get the RL-22 or the IMR to work with those velocities please let me know. Right now I'm shooting H4350 and I'm getting 2400 fps. I'd love to push that up to around 2500 or 2600.

 

[benchracer]

Once I have the bedding issues sorted out, I plan to work with the Cutting Edge 300g and 320g MTH's some more also. I started playing with the 350g SMK's because they are a cheaper alternative while still being a true long range bullet. If I can get the 300 or 320 CE's to work, along with the 350g SMK's, I will have a serious long range hunting load along with an affordable practice load.

I will definitely share my results along the way.

BTW, my initial hope for the 350's was 2500 fps or so. When my Magnetospeed started showing 2600+ fps, I was ecstatic. Accuracy may or may not come in at or near 2600, but I am confident that 2500 to 2550 will easily be doable.

 

[Cold Trigger Finger]

CZ barrels are pretty hard but turning the H+H into a Ackley or Weatherby ect will get rid of most of the case stretching and give quite a bit more case capacity.
My 375 Whby gave full 2700 fps with the 300 gr SGK for a 24" barreled Number 1 .
Course with a CZ550 you can always RUM it. If the RUM would have been available when I started shooting 375s at least in crf stainless rifles I never would have spent much time with the H+H. My CZ 550 acted like they would feed 375 RUM without Too much work when I played around with them with 375RUM ammo that's one of the great things about the 550 magnum action
Lots of depth.in the mag box. . It totally SUCKS that the 416 Rigby was standardized with a 16" twist. With a 10 or 12" twist and some modern LR bullets it would make an Awesome LR brown bear rifle.

 

[benchracer]

I have had similar thoughts about the Rigby.

QL says RL-22 would produce 2632 fps with the 350g SMK in a rifle similar to mine chambered in .375 Weatherby. In .375 RUM, top velocities are produced with VV560 and VV570, yielding a predicted 2659 and 2721, respectively. If both predictions behave the same way my H&H did (approx. +50 fps real world velocities), that would yield around 2680 fps for the Weatherby and 2709/2770, respectively for the RUM. The Weatherby requires about ten more grains of powder and the RUM requires about 27 more grains of powder.

I am able to handle the H&H with the 350g SMK without a muzzle brake. I might consider stepping up to a Weatherby, but I think the RUM would be too much for me. It would be cool to see someone try the RUM, though.

 

[Swamplord]

If you are intent on shooting the Cutting Edge 320-330 gr MTH bullets in the 375 H&H or 375 Ruger
I would also suggest a 1:10 twist barrel
My recent testing with these bullets and a Brux 12 Twist barrel with H-4350, H-4831, IMR-4350, IMR 7828 and RL22 with srarting load velocities in the 2400 fps range showed poor accuracy but as loads were gradually worked up the accuracy improved and was outstanding at highest velocities with all powders,
In a 9 lb rifle I was able to print some incredible 1/4" 3 shot groups at 100 yards but most were 1/2" at peak velocity, RL22 with 2950 fps for best accuracy in the Brux 12 twist bbl, a 10 twist barrel should provide similar results at 2400-2500 fps

Brux barrels and Cutting Edge bullets are seriously accurate when used in a proper twist/velocity combination and the OP made the right choice by going with a 10 twist

 

[Swamplord]

If you are intent on shooting the Cutting Edge 320-330 gr MTH bullets in the 375 H&H or 375 Ruger
I would also suggest a 1:10 twist barrel
My recent testing with these bullets and a Brux 12 Twist barrel with H-4350, H-4831, IMR-4350, IMR 7828 and RL22 with starting load velocities in the 2400 fps range showed poor accuracy but as loads were gradually worked up the accuracy improved and was outstanding at highest velocities with all powders,
In a 9 lb rifle I was able to print some incredible 1/4" 3 shot groups at 100 yards but most were 1/2" at peak velocity,
RL22 @2750 fps for best accuracy in the Brux 12 twist bbl, a 10 twist barrel should provide similar results at 2400-2500 fps

Brux barrels and Cutting Edge bullets are seriously accurate when used in a proper twist/velocity combination and the OP made the right choice by going with a 10 twist