Powder burn rate question

[futuretrades]

My question about burn rates is this; Will a powder with a faster burn rate, increase velocity? I understand there are a lot of variables involved here. I am asking because, I am still trying to find a load that I can shoot in my 20VT, and keep the velocity from decreasing too much. The weather and a few other thing have been keeping me from testing my current loads. From some of your posts concerning the Vartarg, I see a lot of you are using RL7, or H4198, of which I have tested thru my rifle. I tried 17.5 grs RL7, W/32gr Vmax, the load that was suggested to try for fire forming my brass. This load caused, what seemed an over pressure. Reduced my load to 17grs. RL7 and no more problems. I also tried H4198 @ 17.5 grs , with no problems, but if I increase powder charge by as little as .1gr, I will start getting a hard bolt lift. I also tried RE10x @ 17.8 grs, and no problems. And I did shoot some loads with H335 @18.3 grs with no problems. RE10x, as listed on my powder burn rate chart, is listed 6 spots slower than RL7 and H335 is 11 listing slower than RL7. With the slower burning powders, I am able to increase powder charge by more than 1 full gr. of powder with no problems, even when jamming bullet into the lands
All other tests were done with 32gr Vmax bullets seated to just touch the lands, and when I had some trouble, I backed the seating depth .020 off the lands with no change.
Until now I have no experience with a rifle that I can seat a bullet at or into the lands. I am at a complete loss!

[Ol` Joe]

Velocity is related to time under pressure. A "fast" powder for the app normally doesn`t keep (peak) pressures up for long enough to achive top velocity, too "slow" a powder the opposite. You need a powder with a burn that will match the chamber bore ratio of the rifle and reach peak pressure relatively quick while being slow enough to keep that pressure level for some time after it is reached. The books will show what powders give the best velocities in their labs. Those powders should give the best in your rifle too.
Setting abullet into the lands will change the burn rate of the powder depending on the resistance offered by the throat on the bullet. You can increase velocity this way but be aware pressures are increased to and they don`t usually jump in a linier manner relative to velocity

[Fred_C_Dobbs]

QuickLoad, the consumer-level internal ballistic software, has six different user-adjustable powder properties in addition to a "burning rate factor." And those don't include the physical characteristics of the cartridge that affect the pressure curve but have nothing to do with the powder's combustive properties, like primer brisance, the chamber-bore ratio or even the mass of the gunpowder charge compared to the projectile.

EDIT:
Bottom line, burn rate is a catch-all phrase that's only slightly better than meaningless.

[Darkker]

I don't think I understand what you actual question is, as you sort of rambled on about your loading notes...
If you found loads that work for all of your listed powders, why are you now lost??

Dr.(?) Denton Bramwell did a series of experiments showing that in less than 30-06 cases, there is NO difference between primers, NOR magnum primers; in terms of velocity or pressure.
That said, powder burning rates are approx. They depend upon coatings, and case volume. Slower powders burn... slower. Thus the bullet is going down the barrel farther, and the volume to "fill" is greater. This makes it difficult to reach full pressure, regardless of(almost) charge weight.

The most flexible powder, is the one that has the largest charge weight - to velocity swings for a particular bullet.

[Rich V]

Short answer is no. Faster burning powders won't necessarlly give you higher velocitys. Also each lot of powder may burn different than another lot, of the same type of powder. Therefore each lot is given another number from 1 through 10 that shows how each lot burns. With small cal. rifles were tenths can make a difference, one should work their pet load back up when going to a new can of powder.