how much more velocity?
- Thread starter tayhot
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Tumbleweed
Well-Known Member
Not sure what bullets you're using, barrel length or if this is close to your max load. Something I have noted in the past: I rifle's barrel can only burn so much powder. I have worked up a couple of loads in my 300RUM where you get close to max load or even a tad above and you stop gaining velocity even with more powder. The pressure signs seem to increase on the case but you can get to a point that the rifle will not produce more velocity even with a grain or two more powder. In this case I have backed down the powder charge until the velocity just starts to fall off. So to answer your question, in your big case chances are you won't notice a difference with .5 grains unless you've got very tight ES with our current load. Hope this helps. Of course, watch for too much pressure!
Long Time Long Ranger
Well-Known Member
I assume the 300 grain bullet since that is a very popular load you listed there for the 300 grain in either 338 RUM or 338-300 RUM. You are at the top end with that load and is max in most rifles. It is a load I used back in 2001 when the 338 RUM first came out and I was comparing it to the 338-300 RUM I had been doing for a couple years back then. As you go higher even in 1/2 grain increments you can get into pressure spikes with severe but inconsistant velocity increases. If you are getting low extreme spreads where you are I would stay there. You can kill about anything in north america as far as you can hit it with that load. You don't need any more if this load is accurate.
Fiftydriver
Official LRH Sponsor
I would agree, if your getting 2960 fps with a 300 gr SMK, your FAR over where I would be comfortable with most 338 RUMs. I would not go any higher in powder. Do not get sucked into the "Grass is always Greener" disease!!! OR that dangerous "Tinkeritis" condition.
If your load shoots well and is consistant, I would get off load development and move to practical field shooting practice. Personally, I would drop 75 fps off your velocity if your using a 300 gr bullet personally.
If your load shoots well and is consistant, I would get off load development and move to practical field shooting practice. Personally, I would drop 75 fps off your velocity if your using a 300 gr bullet personally.
Fiftydriver
Official LRH Sponsor
That makes a big difference. 3000 fps should be pretty comfortable at least. Possibly even a bit more depending on your barrel length.
Long Time Long Ranger
Well-Known Member
Ok, I feel better now to. That would be scary pushing a 300 grainr like that in the 338 RUM particularly if it is the new H-1000. My load was with the old powder and although I am still using it and have not shot the new I hear you will not load 93 grains with the 300 any more. That sounds like a good load for the 265 and you could go up 1/2 grain at a time there and see what you get. I have got some very good results with that bullet.
6.5Express
Well-Known Member
I agree with the first response. Typically, you should see "roughly" equal incremental increases in velocity with incremental increases in powder charge. When velocity stops increasing with increased charges, it might be time to go the other way. That is if your ES isn't too extreme.
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T3-OleMan
Well-Known Member
Thanks!
LTLR or any one else hear any more poop on powders or primers that have noticeable changes? GOOD INPUT-MERRY MERRY AND HAPPY HAPPY!
lightbulbLen / Dick: Would we want to have a pinned post that people could add powder or primer possible "changed conditions" too. Might save a life?
Long Time Long Ranger
Well-Known Member
The new batches starting maybe two years ago now of H-1000 are faster than the older batches I worked with developing loads for the 338-300 RUM back in the late 90's and the 338 RUM when it was introduced in 2001. Many guys work near max and the old 93-94 grain load with the 300 grain bullet could be very dangerous with the new H-1000 powder from what I hear. As I said I have not used the new powder but have read many times on here where it is faster by 3+ grains which is enough to be dangerous.
Other powders you need to watch out for are the old H-870 and accurate 870 which can vary by nearly 10% batch to batch and with temperature. Buy it by the keg so your load will be good for awhile and not have to change it with every pound of powder you open. H-1000 did well in a number of cartridges so I bought a few kegs and still using it. I think the new batches may be to fast for most purposes I use it for now.
Other powders you need to watch out for are the old H-870 and accurate 870 which can vary by nearly 10% batch to batch and with temperature. Buy it by the keg so your load will be good for awhile and not have to change it with every pound of powder you open. H-1000 did well in a number of cartridges so I bought a few kegs and still using it. I think the new batches may be to fast for most purposes I use it for now.
