I'm working up a load for a 375H&H using a chronograph. The load consists of: 270 grain XLB (Barnes X with blue coating), Winchester brass, Fed.#215 primers, and 3 different powders (RL-15, H-414, & W-760). My Barnes Reloading book lists all 3 of these powders giving +2800fps velocity for max loads. I loaded 3 rounds of each starting 2 grains below max and going up to 1 grain above listed max (I could pull the bullets if I saw any pressure signs - I didn't), in 0.5 to 1 grain increments, depending on the powder. None of the powders reached the listed 2800fps level, 2 of the 3 didn't even break 2600fps (even when loaded above max). The chronographed velocity increase averaged about 20-40fps per grain more of powder (no velocity jump or decrease in velocity with more powder). Also, all 3 powders were cosistently slow vs the mannuels listed velocities (i.e., slow in my gun). There were no other signs of pressure (i.e., flattened primers, difficult extraction, etc.) My question is: would it be safe to go up another 1-3 grains (based on my trends for each powder) to reach the book listed 2800fps velocity level, watching for pressure signs along the way?

MHC, let me ask you a couple of questions. I don't have my Barnes #3 manual here in front of me, but make sure that you're using the data for the coated bullets vs. the not coated. The coated bullets need more powder to get to the right velocity. Also, what is your barrel length compared to what they used to develop the data? If you're shooting out of a noticeably shorter barrel, that could account for some of the velocity shortfall. As for the rest of your question, it is my belief that loading manuals are more of a rule of thumb or a starting point rather than an "end all be all". It could be that your rifle needs more powder to generate the right amount of pressure, due to the length of throat or the size of the bore etc. If I was in your situation, and you don't see any suspicious pressure signs etc, I would push on, but do so with caution.

What obvious signs of pressure are you looking for? Mic the case heads and increase in .2gr increments VERY carefully. And remember, that extra 50fps isn't going to be worth it if you lock up your gun on a hot day as that 6X6 runs by.

MHC,
i'll ask what I consider to be THE relevant question

what performance does the gun have with other loads, bullets, and powders?

Is it close to book with say sierra loads?

you might have a "slow" barrel... happens...

what length is your barrel vs the one in the book?

If it were me, I would try some classic 375 HH 300 grain loads, and see what the results are when compared to book

be SAFE please

jeffe

Let me guess......the two powders that didn't break 2600 were the 760 and the H-414 ?

The thing is , even with 3 or 4 more grains , I doubt you will reach your goal of 2800 fps.

I just did some loading with the 235 gr XLC in a .375 . A load they(Barnes) listed at about 3050 fps only did a little over 2600 with that light bullet . Most loads were a good 150 fps below what Barnes claims.........I think in many cases the velocities claimed for the .375 H and H are wishful thinking........you might try H4350 . That powder has worked very well for me with a couple of different .375 bullets........

All (1st thank you for your input)- I have a 23" barrel on my 375H&H vs a 24" barrel for the rifle used in the Barnes Reloading Book (volume 3). I am using the reloading data for the coated bullets. My 300 grain load chronographs at 2580fps vs 2600fps (Nosler Book), which is pretty close (again my gun has a 1" shorter barrel). The load that reached 2600fps was with W-760.

MHC,

My experience with reloading manuals is that my loads never reproduce the results listed. I never have been one to try and drive a bullet near max. I prefer to find a moderate, accurate load. At the ranges you will be shooting in Africa those should serve you well! Just my opine.

This is not going to make up 100 fps but be sure to adjust your chronograph figures to the muzzle.

While you may indeed have a "slow" barrel I seem to have a "fast" barrel in my .375 H&H. Everything I put through it seems to be at least 50 fps faster than published figures.

My rule of thumb is never to exceed either the charge or the velocity of a published load, no matter where that leaves you. I follow that tenet and have still been charged here as dangerously overloading, even when furnishing documentation of published sources. So be careful out there.

I agree with jackfish on this...

and are you deadset on using this bullet?

I have found that "lubicated" or coated bullets, tend to run slower than I expected.. even though you have book loads for these...

interesting issue....

jeffe