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balzout
10-20-2008, 03:58 AM
Well the wind finally layed down enough that I could shoot my first batch of reloaded brass. Hate to sound simple, but it was kind of exciting. I'm using H50BMG powder and the published numbers that I found were 114gr. to 120gr. so I loaded 5 shells of each. I started with the lighter loads and was pretty happy with the group at .730 at 100 yards. Next were the 115's and the pattern grew a little to a full inch and raised about one inch. When I shot the 116's they went kind of wild to 2.400 and raised another inch. I thought this to be kind of a drastic jump for only a one grain change. The 117 and 118 were slightly tighter at around 1.800 and still slightly higher but only by .300.

The question : I see a pattern of increasing size as the powder load increases. Would it be wise to lower the charge by one or two grain to see if the get any tighter, or should I change powders and start all over? If I do lighten this load, will it probably continue to drop in elevation? The reason I shoot this gun is for it's long range ability. Thanks Larry

runfiverun
10-25-2008, 11:06 PM
you are seeing what is called the ladder method you will find a spot in there
where a grain or so of powder won't change much elevation wise or group size.
it seems that you are right at it's door.
you didn't mention your velocities or how full the cases were ,as i am not familiar with
[know of it. just don't reload for or have one] this particular case.
assuming it is your 30-378.
the best i can do is guess at your burn rate.
but what you will generally find is that a particular powder will give good densities[case full or nearly full] and velocities.
this is generally your best bet as far as a powder to work with.
if your velocities are higher then expected or lower your powder choice is not a good one.
or you are using too much or too little.

but if you are below maximum load and pressure i would continue to increase the load and watch what your groups do.
they may continue to get worse or they may pull back together.

some rifles like the higher loads for accuracy. like my 0-6
some more near the lower end, like a 7 mauser i have.
velocity is okay for long range. but you gotta load for and shoot at the range you are going to use the rifle for.
a 100 yd load is probably the best at 100yds and not at 5-600 yds.
a lot of the nra high-power guys shoot one load from100 to 300 and another one at 600.

reloading for target work is a tough game,fun but nervewracking.
and part of the curve is trying and trying again.
consistency,change one thing at a time. then when you get that rifle working well, along comes another one and someone changes the rules.

be safe.

balzout
10-28-2008, 04:44 PM
Thanks runfiverun for the return.

Let me see if I understand what your saying. I should be looking into the % of case capacity to find a powder that fits my needs? I thought these were the parameters that were in the manual. I reached case capacity at 117gr. When I loaded the 118 and 119, I could hear it compressing the powder. So if my gun did not like these higher loads, could it possibly be that the case was "too full"?

Do I need to know my bullet speed to gain accuracy? I am not opposed at all, just didn't realize how it played in the equation. Is this more valuable when switching powders to keep track of velocity after finding best group, or is it possible to find that my gun likes a particular velocity, and all powders are accurate at this speed?

I am not trying to build a bench rifle, and I'm not saying that is what you said, but if I reload my brass and find the tightest group at 100 yards, isn't that also my best group at 500 yards? Thanks again, Larry

runfiverun
10-28-2008, 10:33 PM
if your case is so full that you are compressing[a lot] the powder you can actually be changing the burn rate of the powder some.[ especially when using a stick powder ]you are breaking the powder into smaller pieces and exposing more surface area.

the velocity is an indicater of pressure if you add another grain of powder and your velocities don't go up [ they will some but 15-20 fps ] you are in the high pressure zone fully.

the reason you can gain more velocity with a slower powder is because you reach peak pressure at a later time.
how this works is you have moved your bulet down the bbl and the powder is still pushing it and burning, so you are producing more gas over a longer period of time.
you can go too slow and not reach full velocity because the bullet has moved too far down the bbl and you cannot reach the proper pressure for the powder to burn fully.
i am trying to keep this all jacketed bullet related, as for cast it is a different game altogether.

the same velocity for different powders and getting the same groups thing.
no, i have never seen it work this way, i have seen it be close but not the same.
when i work up a load for my hunting rifles i do target a certain velocity, i do this because the bullet i want to use performs it's best at these velocities.
i try to hit that speed with a few different powders try them and there is usually a clear winner, i then fine tune this load, change cases,,primers, seating depths,and powder amounts
slightly.
what you are looking for in accuracy is for the bullet to leave the bbl at the same point of the bbl's vibrations.
what you are doing with/to your cases is giving the bullet it's best chance at entering,travelling through and exiting the bbl in as straightof a line as possible.

your best 100 yd load could be your best bet at 500,or not
your worst load might be better at 300.
i know this sounds like a cop-out, but you gotta try them at the longer distance.
your loads that don't look so good at 100 might be better at 200 or 300
it is a matter of how fast your bullet is spinning,it might not have settled down at 100.
and still have some yaw to it.
this is also influenced by velocity and powder selection, faster powder= harder start to the bullet but lower muzzle pressure.
velocity or lack of it = time of flight, your bullet is gonna turn the same amount of times on it's way to the target.

fully confused yet??
you say you hit a case full at 117 grs,and had some compression?
have you tried to see how much you can get in a fired case?
you might want to try neck sizing the cases, what this does is gives you a copy of your chamber for your powder platform, it also will increase your case life.

what knowing your velocity does, is give you an idea of pressure, if you have a tight chamber
you will use less powder to reach a higher velocity and max charges in the book will be over max in your rifle.


even after all this, if your rifle don't like the bullets you are using you will only get so much from them.
treat each gun as if it were a wild-cat, cause they are.
i have several rifles in the same caliber made by the same company and it seems they all like something just a bit different, i have 2 k-31's one likes h-4895 the other imr-4895.
same bullets same primers and case brand. go figure, they both shoot under 2" with open sights at 100.
just don't mix up their loads or it is more like 3"

balzout
11-04-2008, 07:41 PM
Thanks for taking the time runfiverun. Just got back from hunting and I'm ready to get back at it. Your post has a ton of information that has me scratching my head. I think I'll slow down a bit.


if your case is so full that you are compressing[a lot] the powder you can actually be changing the burn rate of the powder some.[ especially when using a stick powder ]you are breaking the powder into smaller pieces and exposing more surface area.

So your saying that when the load is compressed that possible inconsistencies may occur? I took a round pencil and ground the end to simulate the back side of the bullet that I was shooting. I found that by loading the brass with powder, inserting the pencil and turning it upside down and tapping it slightly with my finger to get proper bullet inset, I could get 114.8gr. with what I would call completely full/no compression. Could this be why after the 115 group the pattern got erratic? Is it common to think that a compressed load creates more variables than a non compressed load? I did load an unresized brass to compare with my pencil test and found that it was able to hold 1.3gr. more powder than a full length resize. This information is helpful to know that I'm what, over resizing, or have case capacity if I need it, or....?

As far as the chronograph goes, if it's a player in gaining accuracy, I'll put it on my wish list. You commented that the velocity curve does not necessarily follow the powder load. So maybe I started this off on the wrong foot. Should I have maybe first found my case capacity as stated earlier, then loaded only one shell of each powder increment, done one shot groups to gather velocity data, ( to make sure I'm below the overpressure threshold) then started with the five shot groups?

I'm actually having a great time so far, just have shot almost a whole box of bullets and don't know if I'm getting any closer. My shoulder says I should do more research and a little less shooting.:wink: Thanks Larry

versifier
11-05-2008, 12:56 AM
My favorite piece of gear when I have a lot of testing to do is a Past Recoil Shield. I have the Magnum version, and with it I can shoot most anything all day comfortably. Sitting at a bench exposes your shoulder to much more abuse than it gets shooting offhand. The idea for testing is to remove the human element as far as it is possible, so it is fairly counterproductive to add a flinch into the equation. ;-)

runfiverun
11-05-2008, 02:40 AM
you are catching on quickly to what is happening here.
you have more case capacity [as you have found out] by only neck sizing your cases.
you have also found that what the books say and what your rifle says are two different things.
this is where the chrono comes into play you may be hitting the velocities you want
[think you are getting by the book]
or not depending on exactly how large your chamber really is. and youur bbls exact size also.
by only neck sizing, your cases will last much longer,and if you learn to anneal they will last much longer.
you will also gain some accuracy from this as it should help hold your bullet in better alignment with your bbl.

a highly compressed load will also give erratic pressures due to the fact that it is harder for the primer to ignite the powder uniformly,and the neck has a hard time holding the bullet in place with all the pressure behind it, your bullets may actually be getting longer
in length but at an uneven rate.
in my 308 i use a highly compressed load of h-414,what i have had to do to control them from getting longer is to actually neck size them, and notuse the expander ball, to have enough neck tension[.006] to keep them in place. i also have to flare the neck so i can seat the bullet straight and then iron it out with the seater die.

one other thing a chronograph will tell you is your shot to shot variation in velocity.
some people say a wide [50 or so] fps variation has no effect on accuracy.
50 fps might not be much at 100 yds but 150 is and you can see the stringing on the target.
which i am betting you have already seen with the heavily compressed load.
another side note here, my daughters rifle actually will throw the higher velocity rounds lower than the lower velocity ones, when her load has a wide deviation.

versifier
11-05-2008, 04:18 PM
my daughters rifle actually will throw the higher velocity rounds lower than the lower velocity ones, when her load has a wide deviation.

That checks. The lower velocity bullet spends a longer time in the barrel and exits farther into the recoil impulse, so the muzzle has risen just a bit more at exit compared to the faster bullet. Again, the longer the range, the more noticable it is - you might not even see it at 100yds, but at 200 or beyond it becomes more and more obvious. That's one reason why SD isn't as important a consideration with handgun rounds, because the ranges are so much shorter compared to rifle rounds.