Accuracy at max pressure

Dogleg

Dogleg

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Why is it that most sources will say that best accuracy is usually at the low end of the charge scale, when my own experience has been the opposite?In nearly every caliber I've loaded for the groups tended to pinch down right around the time to quit. In many cases loads that were obviously too warm out-shot the loads I had to settle for. Of course, hot or cold some loads just aren't going to shoot no matter what, but I see a different pattern than I read.
I'm not necessarily promoting hot loads, and at the risk of being accused of heresy don't necessarily believe that in most hunting situations the last bit of accuracy is even all that important. I'm just saying that I don't put much stock is the "Starting loads shoot better school of thought". I'm more of the "Powders are more consistant at the pressures they were designed to run at" thought pattern.
What has been the experience of the board? Are the manual writers so firmly locked into CYA mode that they are scared to say anything else?
 
i too have found my best loads a usually at the top end. i had a ruger 300wm that would tighten the group the hotter i loaded. my best groups were with loads that we too hot to be safe. all in all the differences on hotter loads were small. not enough improvement to warrent unsafe loads. i try and not exceed book loads for most of my rifles unless velocity is obviously too low. some rifles will not reach book velocity with the loads recomended.
 
My experience has been with low end gave me better result, but my thought were always try to match the load to the rifle to create minimum barrel harmonic vibration at the muzzle.
 
It boils down to what works in your particular rifle--I have had some that worked best at full power, some that were best at starting loads and many that would be poor with starting loads--groups improve as load gets hotter up to a point and then the groups would open up. There is no real way to tell except by careful testing.

FWIW, 44Bore
 
Accuracy at top vel.

I'd agree that each gun is different. I'd probably say more of mine have shot best at full power. Actually I'd deffinately say more of mine shot best wide open.:cool:
 
I think it's got to do with modern manufacutring process and tight tolerances.

Older rifles tended to shoot better with lower pressure loads due to looser tolerances, but peopel still kept repeating the same storyeven though we have the tighter guns these days.:)
 
Here's another long time reloader that has often found "warm" loads shooting the best. I have had a couple where groups were still getting smaller when I had to quit due to obvious pressure signs. Each rifle is a law unto itself, though, so results vary. There is often another "sweet" spot for accuracy, but my findings were that this was often well below the potential of that chambering. The odd barrel shoots everything quite well. Go figure! Regards, Eagleye.
 
A barrel will normally have different accuracy "nodes". If you tend to find yours up high all the time, it may be the way you are developing your loads.

I can usually find 2 accuracy nodes and always pick the lower one.
 
With cast bullets best accuracy is achieved as pressure matches the tensil strength of the bullet. Perhaps the same thing is going on with jacketed however the jacket is much harder and therefore takes greater pressure to become elastic.

Who knows. There must be some Physicist gunnutz to shed some light on this.
 
My 99 Savage liked loads a bit below max, so did my 338WM in my Browning Stainless Stalker, My '92 Winchester in 44-40 hates anything above 1300fps, although I have loaded it to 1850. The Winchester 94, 30-30, it likes it hot, But my wifes '94, it likes minimum loads.
I guess my point is that rifles are unique. Pay attention.
 
Is there anything wrong with shooting warm/hot loads if your gun shoots its best at that point(not over max in the manual)? if you are not seeing signs of pressure what is the problem? why not shoot them ?
 
BCboy said:
Is there anything wrong with shooting warm/hot loads if your gun shoots its best at that point(not over max in the manual)? if you are not seeing signs of pressure what is the problem? why not shoot them ?
Click to expand...

Oh, I don't have any problem with shooting maximum loads, I prefer them. In fact, for most of my cartridges if they don't shoot at or near max I'll try a different load until I get what the cartridge is capable of. I don't have any interest in making a .308 out of a .300 mag for instance, I have .308s for that. I'm just curious why so many people preach that moderate loads tend to shoot better, when on average I've found that the hot loads shoot better. If for some reason I want mild loads I'll go right down to cast.

Jasonburnsdundee,
I know exactly what you mean about the cast bullets, but it doesn't apply to jacketed bullets. They don't obturate, or bump up.
 
smak_daddy said:
A barrel will normally have different accuracy "nodes". If you tend to find yours up high all the time, it may be the way you are developing your loads.

I can usually find 2 accuracy nodes and always pick the lower one.
Click to expand...

This is what I find with my rifles. How many nodes I find depends on rifle and bullet I'm using. My 6BR, for example, has 3 nodes using Varget and 88g Berger. It has 2 nodes using 90g Scenar bullet. I did not find a node at the hot end of the loads with the Scenar and I checked. My 308 Sportco showed 3 nodes with 155 g Amax and 155 g Berger VLD's. In no case did I find the hottest loads to be the most accurate, though the hottest load is still pretty hot (2830 ft/sec average; range about 15 ft/sec). My 308 tends to shoot more accurately about 0.5g below max. How hot a load I select depends on what I am doing. If one is shooting in matches, e.g. highpower silhouette where each match is 40 shots, many choose the load that is just sufficient for accuracy. It makes sense to minimize fatigue that comes from muzzle blast and recoil. With hunting I load for accuracy first, then velocity, which I want to be as high as possible and still give good accuracy. My 3006 has 3 nodes with the bullet I am shooting and the highest node is about 0.5 to 1.0 grain below max. This is where I load. I'm working up the nerve to do my 340 Weatherby now, as somehow it has slipped through without being extensively tested:D.
 
I've found that most of my rifles like loads around listed max; some even above that for accuracy.I have noticed in my Sierra reloading manual that some of thier reccomended "accuracy" loads are thier hottest loads for whatever caliber they are talking about. Nosler site on the web also has some of thier hottest loads noted as also being the most accurate. This is one of those innacurate generalizations I think...
 
BCboy said:
Is there anything wrong with shooting warm/hot loads if your gun shoots its best at that point(not over max in the manual)? if you are not seeing signs of pressure what is the problem? why not shoot them ?
Click to expand...

If YOUR rifle shoots accurately without pressure signs where loads are not above the book max ,then I see no problem.
 
load density

The closer the powder fully fills the case capacity the better the accuracy. (load density) Perhaps the loads that are in the upper power levels also reach better load density.
A balance of load density to exit pressure is achieved by selecting the right powder for the application. Too fast a powder and the load density goes down because peak pressures are reached before fully filling the case capacity but the pressure at the muzzle is lower the faster the powder. The slower the powder the better the load density but pressure on bullet exit is increased and the possibility of bullet upset increases. Some cartridges have "favourite" powders that are the perfect match of burning rate to case capacity with standard weight bullets for that caliber.


270 totheend
 
I checked 6 different manuals at the gun counter for my 300 win mag with a 180 gr bullet over 7828 powder.

The min/maxes varied widely. Some of the starting loads were above the maximums in another book. I loaded up a ton of cartridges in 0.5 grain steps going though the whole range. My best group of 5 was with 68.5 grains. I've repeated that group a few times now with the same load. My lowest found starting load was 66 grains and max was 78 grains. My Stevens 200 in 300 win mag definately likes a lighter load under a 180 grain Speer spitzer.
 
hot loads

after about 8 months of testing loads, bullets and powders for my 300 wby. i also noticed the hotter the load the tighter the groups at 100-200 yards. yet my friends 300 shoots better with lighter loads.

kinda reminds me of the wife, the hotter she gets, the better she performs!!
some days i wish i could just lock her up in the gun safe and forget about her for a while, though......
 
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