I am looking for velocity using 260 to 270 bullets. Your barrel length and any pertainent information would be helpful.Do you see any benefit to the weatherby over the ackely improved. I am interested in high BC bullets, and I am trying to duplicate 338 win. mag trajectory,using 225 gr. boattails. I would like to see if it is reasonable to push the 375 bullets to approx. 2950 fps. Any loads that you share would be appreciated.

2900fps+ is no sweat at all in my Weatherby chamber with 260 gr accubonds or 270 Hornaday spire points . H4350 or RL19 powder .

Ramshot Hunter will push the accubond to right at 3000 . Any of these loads should be pretty much identical in trajectory to a warm .338 load with 225 s .

As far as Weatherby versus the AI , the Weatherby does have factory ammo and factory cases available if you don't want to fireform H&H cases. I believe the Weatherby dies will cost you a bit less than the AI dies , those being more or less a custom proposistion .

While I have no proof of it , I have a hunch that the Weatherby cartridge will tend to feed slicker than the AI......a bit more body taper and the rounded shoulder can't hurt there.

I can get 2860 with the 260 accubond out of my H&Hin a CZ-550.shoots almost as flat as my 30/06 out to 300 yards.[within 2 inches].Not 2950 but the trajectory is comparable anyways.

By the way Machinistbutler,How do you like your CZ 550? I just got one, but haven't shot it yet.About the 260 Accubond,have you done any of your own penetration test?How do you like there accuracy?

Here is RIP's data on Saeed's loading section

http://www.accuratereloading.com/375wby.html

John S got very similar results to RIP. I think the 375 Wby or other 375 Improveds are really about the 300 grain bullet because standard H&H gets all it can get with Reloader 15 and 270 grain bullets. But with 300 grain bullets the Re 15 is a bit fast for the 375 H&H and the 4350 to Re 19 burn rate is too slow and that is where the 375 Improveds are picking up....that is they getting a velocity increases that is greater than the increase in powder capacity would suggest.

Mike

I really enjoy the 550.In 375 the recoil is not bad at all,not sure on the larger calibers as the 375 is the biggest I have shot.The trigger is nice,I adjusted it to take up a bit of creep in the "regular"mode.I like the dovetail scope mounts.The inletting on the stock was not sealed too well so I sealed it up.One thing I do not like is the cartridges will rattle if only 2 or three are down. Four or five no more rattling.Mabey needs a stronger spring.The action seemed to bind a little bit at the rear but after working it a bit it has come around.I got lucky I think with my stock,the american,as it is quite nice.Shot it a bit with the open sights then put a leupold vx-2 2-7 on it with leupold mounts.Scope has great eye relief.Accuracy is quite good,have got some 1.25 inch groups at one hundred and even got one group at 200 of about 1.5.The rifle shoots better than I do I suspect>the rifle seems a little heavy but it sure makes shooting it nice.I weigh about 260 so I am not concerned about a pound of weight in my rifle.I will go on a diet before i worry about that. As for the accubond the only penetration tests have been on a mule deer,spine shot 50 yards,pass through.A moose at 90-100 yards entering just behind front shoulder and ending up amongst a bunch of smashed bone in the rear leg.Bullet held together great even after destroying the bone.I WILL USE IT AGAIN.The load I use shoots flat enough for me.Recoil does not seem much different than the 300 gr at 2500 fps.could be a bit less.One thing is this bullet as some other spitzers seat quite deep into the H&H case so powder volume can be affected with slower powders.I actually bulged some cases with 4350 when I was not at the maximum load. This with the noslers and 300 gr hornady interlock . the 300 grain hornady RN has no problem as there is much less bullet below the cannelure.Hope some of this info helps.Hopefully I will see a 375 weatherby at the range and I can try it out but for now the H&H works quite well... Craig

Thanks for the reply about your CZ 550.Sounds like you got yourself a good one. Thats pretty impressive performance on the moose. Sounds like the accubond is worth a try.

Mike

I see RIP really only tried RL15 and IMR 4350 with the 260 gr bullets. RL15 is too fast to be optimum for the Weatherby chamber , and I think he would have seen a little better results with H4350 instead of the IMR . The Hodgdon has gotten me more speed in every instance I've put it up against the IMR , and you can get more of it in the case.

At any rate , I saw a good 150 fps gain with the 260 s and 270 s , from the same barrel , after re-chambering from H&H .

sdgunslinger,

I can't remember what loadings John S was using in his Echols 375 Wby (24 inch) but his gains over his 375 H&H with the H&H using Re 15 were quite small on the 260 and 270 grain.

Are you using a Chrony or Oehler.

Based on energy if you can get 2800 f/s with 300 grainers then assuming equally suitable powders and equal pressure you should be able to do 2950 with 270 grainers.

That about fits actually with the 300 Wby Vs 30/378 and the 378. The 30/378 puts about 200 f/s on the 300 Wby and the 378 is 3000 with 300s and just under 3200 with 270 grainers.

But without Re 15 the H&H really comes down. Even with 300 Hornady round noses IMR 4350 needs to be compressed with a pile driver even when using larger neck sized only brass.

Mike

Mike , I have a Pro-Chrono make of chronograph , I suppose its possible it could be off some but I have tested it against a friend's Chrony and the numbers were coming out very close.

I can believe that John didn't see much for gains with RL15 in the Weatherby case , I think that powder will be a bit too fast. Actually , before I re chambered , I couldn't get to 2800 with the 260/270 s with RL15 in the H&H Winchester barrel. Extraction got sticky for me at about 2750 . After the re-chamber , presto , a case full of H-4350 , 2900+ and the cases fall right out of the chamber . Then the Ramshot Hunter looks really good. It is a dense ball powder and maybe slightly slower than RL19 . You can get 94 gr. under an Accubond in fireformed WW cases (with moderate compression)and push things to 3000 fps. Prssure looks OK . The Accubond is quite a long bullet , so it does eat up some powder space .

If I was wamting to load 300 s in the H&H , I would be using H4350 . The max load quoted in Hodgdon's data really will get right around 2600 fps , and pressure looks to be real easy , and with 300 gr roundnose there is very slight compression .

sdgunslinger,

Even though those powders are made in Australia you get the latest before we do. RIP tells me the H4350 (AI2209)he is using is around IMR 4350 burn rate or even slightly quicker. The stuf we have, well certainly up to a year ago is about IMR 4831 burn rate so you have to get more in the case.

With Re 15 and 270 Hornady and 26 inch stainless match barrels I was at about 2820 or so with 76 grains of Re 15 and 2600 with 300 Nosler and 73 grains of Re 15 and excellent accuracy with both loads, especially the Hornady.

Mike

I didn't hear any mention of 4320,seems like I remember someone here claiming about 2860 fps,260 gr.,. in a 375 HH. Seems if thats true, 2950 fps. in 375 Weatherby should be no problem. Was that you Machinistbutler?

sdsgunslinger,
You are right about the H4350.

I tried it after the .375 Wby "page" was done, and it is by far the top of the heap in .375 Weatherby for use with 300 grainers.

I didn't try lighter bullets than 300gr with it, but I imagine it would do all that anyone could ask with 260 & 270 grainers.

MRP or RL 22 is still the best with 350 grainers, I reckon.

Mike375,
John S and I did have similar results. RL-15 is just too fast in the .375 Wby case to get good velocity with light bullet, without excessive pressure. I stop with ejector slot marks on the case head: brass extrusion. Agreed, RL-15 and 250 to 300 grain bullets work great in the .375 H&H.

A healthy charge of H4350 in the .375 Wby ought to do it with the light bullets under discussion.

Yes I did get 2860 consistently with IMR 4350,It does seem a bit high to me but that is what the chrony says.My 300 gr loads were right at 2500,have some new loads that I will check out soon.I am sure 2950 in the weatherby is no problem.I get a little higher velocity in the 270 gr bullets but for some reason the 260 gr really cook out of my gun.I am not using an excessive load either.With the 375 it is hard to put "TOO MUCH" 4350 in or it will bulge the case.

Machinistbutler: I must have remembered wrong I was thinking about IMR 4320.I sure thought someone said they used that powder.

I once loaded 270 grain X-Bullets up to 2900 fps using 90 grains of IMR 4350, IIRC, but that was a sticky-case-load. I really prefer 300 grainers at 2740 fps for all chores.