Powder burn rate

[HTG]

I'm trying to find out were or if I can compare the burn rates between Retumbo and RL-22, does anyone know were I can find that data?
I am trying to duplicate Hornady 162 gr 7mm BTSP factory ammo. They just told me that RL-22 has the closest burn rate compared to there factory blend that isn't available in stores. But I load for another 7mm and would like to use Retumbo. Just not sure if it would what the results would be.

 

[HTG]

Found it RL-22 rate 198, Retumbo rate 210. Anyone know if ths would make much of a difference? I haven't been reloading long enough to know.

 

[RT2506]

In my new Hornady 7th edition loading manual the burn rate chart has RL-22 at 117 and Retumbo is 125 on a 1 being fastest and 131 being slowest powders.

It goes H-4831, RL-22, VHIT N-165, IMR 7828, Win WMR, H-1000, Magnum, RL-25, VHIT N-170, Retumbo, H50BMG, etc.

Hope this helps.

 

[Clark]

I don't know about those powders, but I do know that almost any chart will show AA#5 as slower than Power Pistol. Yet at very high pressures, AA#5 is faster, per my experiments.

What does it all mean?
A one dimensional burn rate chart would have pressure as an out of control variable.

 

[Michael Eichele]

deleted.

 

[HTG]

I was looking at www.stevespage.com not sure what kind of powder burn rate chart that was. I think I'll end up purchasing two kinds of powders. Still wondering if I loaded two loads exactly the same, one with the retumbo and one with the RL-22 if there would be much of a difference in accuracy? After doing the little bit of reloading that I have I bet there would be. Thanks

 

[MagnumManiac]

HTG,
I think that you being new to handloading, you shouldn't worry about 'burn rate' charts. They are in fact meaningless, because a powder burns completely differently inside a cartridge to the way they get their 'burn rate' chart information, it's called a 'callorimeter bomb'.
In fact, powder 'burn rates' vary depending on the pressure that it is loaded to, and the expansion ratio of the case it is loaded into, in other words, the size of the case capacity, compared to the size of the bore.
I wouldn't try to 'match' factory velocity in your rifle, it simply will not be likely to be able to achieve, they use 'blended' powders which have their 'burning rates' TWEAKED to match their published ballistics, which you simply cannot do with the canister powders we are able to buy.
My best advice is to try the 2 powders you mentioned and go with the one that is more accurate, higher velocity is neither here nor there when hunting is concerned, game animals never know the difference between 3000fps and 3200fps.

Just for your information, Retumbo is quite a bit slower than RE22 and may not work as well in the small case of the 7mmRM, but wonders never cease. I think a good powder would be RE25 if RE22 is not up to scratch.
Good luck, and good hunting.
Cheers.
MagnumManiac.
gun)

 

[HTG]

Magnum Maniac,

Thanks, I haven't really been able to duplicate the accuracy of the Hornady factory ammo. I thought I would try the Berger VLD because I've heard all of the good reviews about there long range capablilities but they didn't shoot well with the the gun I loaded them for. I finally got it to about 1/2" at 100 yards after about a 100 rounds and several different loads but didn't see much improvement out to 300. So thats why I'm going to try the Hornady bullets again. I keep telling myself that I will build a long range set up but I haven't really found them very useful in the field.

 

[Freebore]

HTG,

I shoot a 7mmRM too and the best powder for velocity and accuracy with the Hornandy 162gr BTSP is RL-22. I'm shooting a Browning A-bolt. At least in my rifle it works well. Your's could be totally different.

 

[HTG]

Freebore,

I going to try the RL-22. I'm thinking about going back to the factory ammo because of the accuracy I had with this gun but I will have to try this load. Thanks

 

[4xforfun]

This is what I use:Powder Burn Rate Comparison Chart @ www.reloadersnest.com