Powder of very similar burn rates and powder choice

I have read much about powder burn rates and burn rate charts, some "experts" claim they are useful aid in powder selection, other "experts" claim they are useless. Which lead me to this question I have not the knowledge or experience to answer.
Not to long ago I purchased a Tikka T3 Lite in 300 WSM. At the time well over a year ago OTC selection for suitable powders near me for the 300wsm and 180 grain bullets was rather limited. Of the most strongly recommended powders by members here I was able to only get RL17, the others IMR 7828ssc, H4831sc, MagPro, and Retumbo were no where to be found OTC and even mail order was little better and the Hazmat fee required I order several pounds or it was IMHO to expensive.
Well the RL17 experienced pressure signs just as its accuracy was peaking so I was kinda at a dead end for powder selection. I wished to avoid using a powder that was available only a few times a year and wanted that powder to be available OTC if at all possible. I was sitting in my reloading room mulling over my powder options, when I noticed I had IMR4831 I had bought to try in my 338wm but never used and figured WTH, it cant hurt to try it.

I loaded up reloads in .5 grain increments from 65.0 up to 67.5 grains. I got pretty good accuracy with no pressure signs with every loading, but the 67.5 grains was hands down best. I reloaded more of the 67.5 IMR4831 with 180 grain bullets and shot three consecutive 3-shot 100 yard groups all under .6" the third and best group was right at 3/8" and decided to try a 5 shot group and it opened up to only .5". My 200 yard groups were all well under MOA.

Needless to say I have found FOR ME and my accuracy standards, the powder for my Tikka T3 and 180 grain bullets. Unfortunately for me I am an insatiable tinkerer and as fate would have it most of the powders I couldn't get before are now available OTC.

Now for my question. To help in narrowing my powder selection can I use a relative powder burn rate chart by finding a powder who's burn rate is very close or equal to that of IMR4831 and try it? MagPro, Hybrid 100v, and H4831sc are listed as very close to having the same burn rate as IMR4831 so should I consider them more likely to yield equal or better accuracy as does IMR4831 based on them all having very similar burn rates? Or are burn rate charts not reliable enough to be used or are not intended to be used to aid in powder selection.

Thanks,
DJ/Art.

I just printed a new burn rate chart last week that had updated powders and have been looking at it pondering the same question, but the opposite way....if you have negative results with a powder, would you try another powder with similar burn rate, or one further away on the chart? I'm here to learn!

The burn rate charts are roughly accurate. Your IMR 4831 will often have more pressure than H-4831. It did in my 280. I just backed off and reworked my load.

I prefer to look at the Hodgdon's Extreme and IMR's Enduron powders for most of my needs, as they are not as sensitive to temperature. Then I check velocity/pressure on Hodgdon's site for a given bullet wt. & barrel length. Pick a couple and try them.

I'm to old school to fully relay on burn charts, I'd rather study powders that were made to run in certain cartridges that I have . Powder company's compete against each other for bragging rites and sales ,that helps us the consumers . For sure try Magpro,& Retumbo,good luck .

Art , this is where quickload really shines . you plug in your info and quickload spits out a powder list from highest velocity , to lowest velocity. it will probably point out a powder that you would have never thought of too . I've seen so many times the next powder up, or down, on a burn chart has a very different velocity .

morning, jjmp is total right. when a favorite powder is hard to find,
due to shortage or whatever at the mercy of the manufactures.
I use the burn rate chart. a very good example is H-780.
a very good powder for the big magnums is very
seldom mentioned. when the middle range cartridges
powders 748, 760, Rl-15, 4320, 4064 were scarce
I used the burn chart. powders-calibers-cartridges
have there happy space. just me GBOT TUM

I look at this way. If you're hitting pressure before an accuracy node, move to a slower powder.
If you're out of case capacity and not happy with velocity and haven't reached pressure signs, go with a faster powder.
In you're case I would try a little slower powder to experiment with

Just country don't you mean Winchester 780 Supreme powder ? Thks

A stick powder like IMR4831 is very different than a ball powder when listed close to each other on a burn rate chart.
http://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=170

http://www.firearmsid.com/Feature Articles/McCord_gunpowder/

I look at powder selection more as a velocity goal than an accuracy goal. I'm my experience I can most any powder to be accurate, but not all to be accurate at the velocity goal. When I select powder I select the powder that will give me the velocity I want with the bullet I have selected. Load Work up to pressure and accuracy. There is no need to switch powders unless you don't get what you want in velocity with accuracy

If you switch powders with very similar burn rates you aren't going to gain much if any velocity, IMO why bother unless your looking at temp stabile or availability

I look to find a powder that gives somewhere in the neighborhood of 88% capacity (+/-) for the bullet I am wanting to shoot, because more often than not that is where I find the best load.

Just because the burn rate is similar between two powders doesn't mean they will react the same. Substitution of powders should only be tried where there is reputable data to back it up.

BTW DJ, why are you trying to find something different when your load shoots so good? Why don't you just buy an 8 pound jug of IMR 4831, even if you have to order it on-line? Just my 2 cents worth.

I hope this isn't taken as a hijack, as it relates to burn rates, so here goes..... I understand powder recommendations per caliber and risks of dabbling outside recommendations. When you are not getting the accuracy you want from a powder, do you typically try another of the recommended powders of similar burn rate or try another recomended powder of differing burn rate? Do any of you see any huge accuracy changes between powders of similar burn rates if all things are equal? Maybe I need to focus more on targeted velocity, but at this point, I was only looking for accuracy. I have never had any trouble getting accuracy within a couple powder trys untill now. This Grendel is beating me at the bench, and I'm trying to figure out what to try next short of buying a bunch of different powder!

Ckgworks said:

I hope this isn't taken as a hijack, as it relates to burn rates, so here goes..... I understand powder recommendations per caliber and risks of dabbling outside recommendations. When you are not getting the accuracy you want from a powder, do you typically try another of the recommended powders of similar burn rate or try another recomended powder of differing burn rate? Do any of you see any huge accuracy changes between powders of similar burn rates if all things are equal? Maybe I need to focus more on targeted velocity, but at this point, I was only looking for accuracy. I have never had any trouble getting accuracy within a couple powder trys untill now. This Grendel is beating me at the bench, and I'm trying to figure out what to try next short of buying a bunch of different powder!

Click to expand...

I'd say this is pretty on topic.
No, I've never seen much accuracy gains by switching powders. I've succeeded in tightening the es of velocity by switching powder and adjusting it to achieve identical velocity in the accuracy node. But I've never found any group size difference between various powders if they're shooting the same velocity.
For example, I've made loads with the 212eldx in my 300wby with 7828, 7977, and h1000. All near 2825fps, they all grouped the same, but es varies between them.
Seating depth can greatly affect the accuracy of your load and some powders get identified as the best for a particular cartridge because they offer good full capacity while leeway in adjusting the seating depth.