Burning Rate Of Powders W/Different Weight Bullets

[Kawabuggy]

I was thinking today about the burn rate of powders, and what the proper application is.

I know that a lot of this is caliber specific so let's choose one in particular for discussion purposes. Let's use the venerable .270.

If I load some rounds up for this caliber using 90 grain varmint bullets, it would occur to me that I should use a faster burning powder as compared to using a 150 grain bullet might require a slower burning powder due to higher pressures as a result of the increased bullet weight.

Is there a set rule in regards to what burn rate should be utilized with what grain weight of bullet in the various calibers? Are there any generalities to go by?

Besides using a chronograph to note actual velocity, how would one determine which is the better powder choice for different loads? If accuracy is the ONLY factor, should one even be concerned with trying a different powder if you have excellent results already?

I have had very good luck with the loads that I am using. But how do I know that I am getting the very best out of my gun? All of my loads are MOA or better, and my on-game performance proves that. Since I am a hunter ONLY (only punch paper when sighting in), do I need to keep searching for new loads using various powders, or just resign myself that I have found what my guns like and just stick with them?

I guess I am just wondering if I am missing anything by not experimenting with different powders. I am also not clear when to use a different burning rate to achieve a desired effect. Further, how would one compare the burn rate of one powder with another powder from a different manufacturer?

[mkl]

Smokeless powder burns in a non-linear relationship to pressure. The higher the pressure, the faster it burns. Remember, non-linear, so while a 2% increase in powder may give a 10% increase in pressure at the lower end of the pressure range, that same 2% can give as much as 40% increase at the very upper end. My example is probably not technically correct, but you get the idea.

If you Google "powder burn rate" or "smokeless powder burn rate" you will find at least half a dozen tables on the web that compare the burn rates of all the currently available powders.

If your are getting MOA groups out of your 270, I'd personally just leave well enough alone and go with what you have.

[Kawabuggy]

Thanks!

[Sport45]

I agree with MKL. It sounds like you have loads that are reliable and do what you want them to. The game animal won't know if you missed by an inch and neither will you since the fur isn't marked with a bullseye.

[SL1]

It really doesn't pay to spend a lot of money and time trying to get another 50 fps or 1/4" of accuracy in a load that will be used for hunting big game.

And, the differences in powders with different names are not necessarily bigger than the differences in lots of powder with the same name. So, you really don't know for sure that you are as close to perfection as possible without trying everything in your own gun.

But, why strive for perfection in the load when you already have one that is good enough? Are you a perfect shot? Probably not. So, maybe you can become a better combination of shooter/gun/load by working on the "shooter" part instead of the "load" part. I find that I have more capability and confidence if I shoot a lot of my favorite load from typical hunting stances than if I keep bench-resting test loads with different ballistics.

And, this is where handloading really helps, because you can make round after round that have the same ballistics (especially if you use a chronograph when you change the lot number on some component), rather than relying on Winchester or Remington ammo to not change ballistics from box to box.

SL1

[ringworm]

Burning Rate Chart (Courtesy of Hodgdon Powder Co.)

(Fastest to Slowest)
1. R-1 Norma
2. N310, Vihtavuori
3. Bullseye, Alliant
4. N312, Vihtavuori
5. Solo 1000, Accurate
6. Clays, Hodgdon
7. Red Dot, Alliant
8. N318, Vihtavuori
9. Hi-Skor 700X, IMR
10. N320, Vihtavuori
11. Green Dot, Alliant
12. International, Hodgdon
13. No. 2, Accurate
14. N321, Vihtavuori
15. N324, Vihtavuori
16. HP-38, Hodgdon
17. W-231, Winchester
18. N325, Vihtavuori
19. N330, Vihtavuori
20. PB, IMR
21. N331, Vihtavuori
22. No. 5, Accurate
23. Unique, Alliant
24. WSL, Winchester
25. Power Pistol, Alliant
26. Universal, Hodgdon
27. SR-7625, IMR
28. W-473AA, Winchester
29. Herco, Alliant
30. N340, Vihtavuori
31. WSF, Winchester
32. HS-6, Hodgdon
33. W-540, Winchester
34. 3N37, Vihtavuori
35. WAP, Winchester
36. Hi-Skor 800-X, IMR
37. N350, Vihtavuori
38. HS-7, Hodgdon
39. W-571, Winchester
40. No. 7, Accurate
41. Blue Dot, Alliant
42. No. 9, Accurate
43. 2400, Alliant
44. N110, Vihtavuori
45. R-123, Norma
46. H-110, Hodgdon
47. W-296, Winchester
48. SR-4759, IMR
49. N120, Vihtavuori
50. XMP-5744, Accurate
51. IMR-4227, IMR
52. N125, Vihtavuori
53. H-4227, Hodgdon
54. N130, Vihtavuori
55. AAC-1680, Accurate
56. W-680, Winchester
57. N132, Vihtavuori
58. N-200, Norma
59. N133, Vihtavuori
60. IMR-4198, IMR
61. H-4198, Hodgdon
62. XMR-2015, Accurate
63. Reloader 7, Alliant
64. N134, Vihtavuori
65. IMR-3031, IMR
66. Benchmark 1, Hodgdon
67. N-201, Norma
68. H-322, Hodgdon
69. Benchmark 2, Hodgdon
70. AAC-2230, Accurate
71. IMR-4895, IMR
72. H-4895, Hodgdon
73. H-335, Hodgdon
74. BL-C(2), Hodgdon
75. AAC-2460, Accurate
76. W-748, Winchester
77. Reloader 12, Alliant
78. N135, Vihtavuori
79. IMR-4064, IMR
80. Varget, Hodgdon
81. AAC-2520, Accurate
82. N-202, Norma
83. XMR-4064, Accurate
84. IMR-4320, IMR
85. N140, Vihtavuori
86. AAC-2700, Accurate
87. Reloader 15, Alliant
88. H-380, Hodgdon
89. N150, Vihtavuori
90. W-760, Winchester
91. H-414, Hodgdon
92. N160, Vihtavuori
93. IMR-4350, IMR
94. H-4350, Hodgdon
95. N-204, Norma
96. Reloader 19, Alliant
97. IMR-4831, IMR
98. XMR-3100, Accurate
99. H-450, Hodgdon
100. H-4831, Hodgdon
101. MRP, Norma
102. N165, Vihtavuori
103. Reloader 22, Alliant
104. IMR-7828, IMR
105. H-1000, Hodgdon
106. XMR-8700, Accurate
107. H-870, Hodgdon
(slowest burn rate)

[Kawabuggy]

Actually, I am a pretty good shot. Perfect? No. But confident enough, and capable enough to take head shots on hogs at 100+ yards, and make them every time.

Appreciate the input from everyone.

[Nnobby45]

Besides using a chronograph to note actual velocity, how would one determine which is the better powder choice for different loads? If accuracy is the ONLY factor, should one even be concerned with trying a different powder if you have excellent results already?

The data found in your loading manuals reflects all the research already done on the subject. For efficiency, see what powders produce highest velocities for a given bullet weight in your caliber.

Efficiently means achieving higher velocities within acceptable pressure limits. The inefficient powders may provide good accuracy and can certainly be used. But I wouldn't go out and buy them just to work up loads with.

As a rule, just think of all the listed maximum loads as being equal where pressure is concerned. And the ones that produce the highest velocity are the more efficient.


You'll discover that heavier bullets do, in fact, tend to achieve highest velocities (efficiency) with slower burning powders, and lighter weights with a little faster burning.


For example, in the '06 using 150 gr. bullets, IMR4064 is a great powder, and for 180's, 4350 is superior. For the 165 either 4350 or 4064 would be good and you'd choose your powder based on accuracy. In fact, all three powders would be suitable for all 3 bullet weights if accuracy alone was the goal.

On the other hand, I'd never use the excellent, but slower burning IMR4350 for 110 gr. varmint bullets, anymore than I'd use fast 3031 for heavy 180 gr. bullets--even if they produced the best accuracy, since the loads would be so inefficent.



Some manuals list "most accurate", as well as "factory duplication" loads. Rifles are different, but that would be a good place to start. You'll find more than one powder that gives efficient velocity. You don't have to go with the highest.

No powder listed in the manual for a load is un suitable. You can try any of them, but by limiting your testing to the most efficient, you'll likely find your accurate load withing good velocity and pressure standards.

The best thing about the less efficient powders is that if a handloader has some of them on hand, he can still find a use for them.

Guess I was a little long winded, hope you find some of the info useful.