How far under max load??
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I use this reasoning with Barnes x ,. so its not new. but much more to it than this, as the compression of powder, or not , bearing surface, distance, etc
But heck , sounds like you got it down, might as well write a load manual
Yup may as well write that manual. Best thing i herd you say today yet!!!! seriously you are a clever fellow arnt you.
Factory loads are all at maximum?
Hmm....Maybe look at some cartridges like the 7x57, 280, 7mmRM , et etc...
OK if i have to clarify it for you...... MOST all factory ammo is loaded at the suggested maximum or really close to it. Would you like me to repeat that only A little slower for you!!!!!
based on the theory of natural selection i would have to think that getting rida you would only make the herd stronger!!!!
It's amazing how one guy such as my selfe can get a whole bunch of guys going all by just making a few sarcastic remarks!!! kinda like going into a grad 3 classroom and telling them all Santa Claus isent real!! Even though he is just as real as god, or the easter bunny!!!
Not really.It takes far less pressure to move the bullet ahead in the neck of the case than it does for the lands to engrave the bullet.The pressure will not maximize until the bullet has reached the lands either way,so the volume is really the same once the bullet is at the lands,regardless of the seating depth.However,if the bullet has a running start at the lands,the lands cut into the bullet easier,resulting in a lower peak pressure being developed.Less pressure results in less velocity.
And this is not just unproven theory.I have chronographed many loads to see this pattern for myself.
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I general , without changing to many things at one time, I can see this..don't have the chroney, and always figured your off or on the lands, and any close stuff was to have more space for powder, or less compression.Accuracy does change..
the only caution I ever followed was that certain mentioned bullets needed a run at the lands to avoid that sudden slow up and resulting pressure build as it hit the lands. How the rifling is cut, how many grooves will all have some effect...
Anyway , all good
- Location
- Somewhere on the Hudson Bay Coast
I for one have seen too many mistakes in the loading manuals to take the published maximum loads at face value in factory chambered rifles. Despite that I keep my manuals current. Several of my rifles have custom barrels with chamber dimensions outside of SAAMI specs, so the published data is little more than a rough guideline in those rifles. When I work up a load I use a chronograph and start low enough that I can watch the velocity increase with regular powder weight increments to determine when I've reached the maximum. This can be done by watching for the velocity plateau which occurs as you approach the maximum load with regular powder charge increments. Typically I like to use 10 rounds with powder increments of 1 gr. The procedure has proven very useful in cases where there has been little or no published data to use as a guideline such as when I began loading 350 and 380 gr bullets for various the various .375 cartridges I load, when loading very heavy bullets for .44 magnum revolvers and for 240 gr bullets in the .30/06. When I am searching for the best accuracy I work up to maximum with the bullet set out well into the lands, then anything I do to tweak the load for accuracy, is done by adjusting away from the maximum pressure, such as adjusting the powder charge downward or by increasing the bullet jump. When I load hunting ammo, more often than not I choose bullets with cannelures and crimp, so changes in the bullet jump is never a variable so it is just a matter of finding the correct powder charge. Besides, hunting cartridges must be short enough to feed through a magazine without hanging up. If I don't get promising accuracy right out of the gate, I'll switch components, but that occurrence is so rare as to be memorable.
Seems intuitive, but I have seen the opposite with the 300 RUM as just the latest. Slightly higher MV when the bullet is set 0.200" from the lands as opposed to 0.050". Loading manuals and "experts" here on CGN consistently warn that seating a bullet deeper raises pressure and that has been my observation.
As for the original question - I typically see best accuracy near or at published max loads. Often at max, but sometimes less, but never far below (i.e. at most 5% below). I have tried a lot of reduced loads and they are never as accurate as hotter loads.
I typically find the best accuracy and velocity rigth around maximum safe pressures. However, often enough a lower pressure load will be quite accurate, too. Here is illustrated several groups starting with low powder charge and getting higher. The first group is very tight but with lacklustre velocity. As the powder charge increases, the accuracy goes downhill, then starts to improve again.
I've seen this happen lots of times...
I've seen this happen lots of times...
This is a good topic of discussion. I've wondered about this myself. Is there a quick way to circumvent some of the time in working up a load. The problems as I see it, with my all couple of months reloading experience, is that every manual seems to have different min and max for a given powder bullet weight combination. Some significantly so.
I think an online database which cross referenced all the common parameters, powder charge, bullet type, rifle model, barrel length and accuracy (subjective) etc, etc, that could be updated by all the reloaders of the world would be awesome. Similar to reloaders nest web site but more comprehensive.
Personally, I don't have time to put this plan into action as I'm too busy working up loads.
EDIT: Actually its not really about circumventing part of the process. Its more about knowing what likely charge area might produce a good load. I would not forgo the work up process just make up less rounds at the lower charges. Phew!
I think an online database which cross referenced all the common parameters, powder charge, bullet type, rifle model, barrel length and accuracy (subjective) etc, etc, that could be updated by all the reloaders of the world would be awesome. Similar to reloaders nest web site but more comprehensive.
Personally, I don't have time to put this plan into action as I'm too busy working up loads.
EDIT: Actually its not really about circumventing part of the process. Its more about knowing what likely charge area might produce a good load. I would not forgo the work up process just make up less rounds at the lower charges. Phew!
- Location
- Hillbilly shack in the boonies
I typically find the best accuracy and velocity rigth around maximum safe pressures. However, often enough a lower pressure load will be quite accurate, too. Here is illustrated several groups starting with low powder charge and getting higher. The first group is very tight but with lacklustre velocity. As the powder charge increases, the accuracy goes downhill, then starts to improve again.
I've seen this happen lots of times...
The barrel harmonics are changing with velocity I figure
I know this steers the thread off-topic and I am commenting on my own comments, but I think it's worth the effort.
The subject of seating depth and its effect on pressure has intrigued me and I did a bit of "Internet Research" (which really means I reviewed the opinions of others). Here's one article from a reputable source - Barnes. Look about half-way down. http://www.barnesbullets.com/resources/newsletters/september-2007-barnes-bullet-n/
Other sources have seemed to be in agreement. Here's the way they seem to summarize:
Pistol Cartidges (i.e. very small cases) - pressure is increased as the bullet is seated deeper; and
Rifle Cartridges (i.e. larger cases) - pressure is highest with the bullet jambed into or very close to the lands (within 0.020"), then decreases rapidly as it is moved away and will then increase again as the seating depth increases.
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- Hillbilly shack in the boonies
Johnn Peterson
CGN Ultra frequent flyer
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- Chemainus B.C.
The seating depth in it's relationship and effect on the actual case capacity is an important factor. In a couple of my rifles, A 308 NM and a 7x61 S&H, to minimize the freebore and because of the length of the magazine I can extend the C.O.A.L. quite a bit. Doing so increases my case capacity considerably.
Generally speaking though in other rifles of say 7x57 case size and larger, where I stick fairly close to the suggested C.O.A.L., I seem to get my best accuracy at roughly 2 grs below the suggested maximum.
Generally speaking though in other rifles of say 7x57 case size and larger, where I stick fairly close to the suggested C.O.A.L., I seem to get my best accuracy at roughly 2 grs below the suggested maximum.
- Location
- Hillbilly shack in the boonies
me three
consistent , be consistent , accuracy begins there.All components, even cases hold different amounts of powder, remmy cases less than winchester for example...
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Use a chronograph and a ladder method of loading.
Good post, this actually answers my original question!! When sticking to suggested C.O.A.L you found your best accuracy at only 2 grains below suggested maximum. that is fairly close to what i usually find. My 243 was best at 1.8 grains below max!!!!!!
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