why does 1 grain make so much difference

[tnctcb]

i loaded 4 shells at each weight and 4 different weights as follows :50 grains, 51 grains, 52 grains and 53 grains.

50 grains was a little over an inch
51 about 3 inches
52 under an inch
53 about 2 inches

this was all h414 powder and federal large rifle magnum primers. is it normal to have that much difference and why.

 

[danr55]

Actually, that's pretty mild. At least you kept them all on the paper.. I would guess that you're loading a fairly reasonable case capacity to bore diameter cartridge...

The reason for the variation is barrel harmonics. When you fire a round, the barrel begins an oscillation in an eliptical manner. The consistancy with which with bullets exits the muzzle will determine, in part, the accuracy of the load. Pressure variations cause the barrel to oscillate at difference frequencies. So you get different points of exit and points of impact for different pressures. When you find that round that hits on a sympathetic harmonic to the barrel frequency, you'll find groups in the sub 1/2MOA range... That will be pretty impressive.

Good luck and keep shooting...

 

[Dano1]

Incedentially,
What cartridge are you Shooting. And what bullet, size and weight, moly or No?

Just curious.

I use H414 out of my 30-06. It has done wonders for that gun.

Dano

 

[tnctcb]

im shooting .270, speer boat tail 130 gr. not moly coated. is moly usually better or not.

 

[Dano1]

Moly is more of a personal preferance anymore since there are many who sing the praises of moly and just as many who say it is worth less.
From my point of view, I do alot of shooting and have been known to shoot hundreds of rounds through a particular rifle in a summer. For me, Moly has reduced the frequency I've had to stop and clean the bore.
It also drops the velocity of the load and requires me to slightly load my bullets with a small amount of powder to bring back to propper velocity. (Don't worry all of my loads are still within book max.) All of my guns are capible of Sub-MOA Accuracy.
I do use moly in all of my guns, but thats because I shoot them so much.

If one was to shoot their rifle a couple of times a year for hunting purposes and the occasional trip to the range, Moly has no advantage over the standard bullet.

H414 Should work well for your .270
I load 150g Sierra Game King bullets in my 30-06 with 58g H414 and a CCI 250 primer. Velocitys are a little over 3000fps. It shoots under 1/2".
I found my load using 1/2 grain increments in test loads. You will be able to see your loads open and close up better if you follow this practice and could have better results for your rifle.

Hope this helps.

Dano

 

[Dano1]

Oh yeah, I forgot.
You still have one grain to go before you reach max for that combo (according to hodogon manual #26).

If you are having no pressure problems with the hotest load you are trying(53g), try 53.5g & 54g. They may be even better.

OR take the most accurate load you've tried and go up and down 1/2grain and see if that tightens the group up even more.

Dano

 

[Dick Reece]

The latest I've read on Moly coated bullets points to it as a cause of barrel erosion and pitting.I've stopped using it before I begun because of it.

 

[tnctcb]

i have a speer, lyman and the manual that came with the press. all of them gave a max of 54 with that load and one even said 55 but since i just started handloading so i thought i would wait on the max load until i got a scale that was easier to read, the one i have is a little weird but it serves the purpose. i will try going half grains and see what happens

 

[Kraven]

Hi tnctcb the Nosler reloading manual I have shows a max load of 54.5 grains of H414 moving at 3062 fps.