Powder Question

[rbadua]

Can anyone explain to me the science involved between using fast and slow burning powder? When do you use fast vs slow, specifically with Grendels. I hear weight of the bullet matters and barrel length. My barrel length is 18" so which powder range should I be using? Any insights would be greatly appreciated.

[Joseph5]

A general guideline is faster powder for lighter bullets and slower powder for heavier bullets. Also with a closed barrel like on a bolt action the longer the barrel the slower the powder, shorter barrel faster powder. With an AR the gas system and it's length influences what powder rate is appropriate also. Then every so often you run into an example that doesn't track with the general guidelines. I hope this hasn't made things any more confusing.

[JASmith]

Are you sure you want to get into a detailed discussion about the relationships between pressures, temperatures, and burn rates. With grain size, surface to area ratios and their effect on burn rate? With inhibitors and accelerants?

Or, are you looking at the more general question of which powder to grab for your rifle and bullet?

Depending on your experience with reloading the choices might change a little bit. Assuming you are just getting started with the Grendel, the best bet is to find commercially published load data (Alexander Arms, Vihtavuori, Hodgdon, Western Powders, Hornady, etc) and choose a load. Some of these sources use 24" barrels to get velocity data. Others use shorter barrels.

In any event, moving from one of the standard powder and bullet combinations to get a little better velocity may get a marginal improvement.

The other reason one might want to try a faster or slower powder than standard is to get a more appropriate port pressure curve to improve cycling reliability. One should try this only after working whatever port adjustments are available. Yes, there are adjustable ports on the market. They have been discussed in other threads in this forum.

[VASCAR2]

I have used these powders in the 6.5 Grendel, AA2230, H335, TAC, IMR8208XBR, WW 748 and CFE 223. A friend uses a lot of AA2520 in his 6.5 Grendel with 120 Nosler BT's. I used the AA2230 with Speer 90 grain TNT and I also bought a pound of VV N130 which is also a fast burning powder. I've considered using N130 with 85 grain Sierra HP but I may use the powder in my 5.56/223. I probably will not use WW 748 in the 6.5 Grendel in the future as it didn't seem to provide the accuracy or velocity of other powders in my 6.5 G's.

[rbadua]

JASmith I live in Hawaii and powder is getting to be scarce since little is ship at a time here. I have loaded with published data but now that powder is becoming a commodity here, I would like to load powder that may be available that I havent typically seen published. What is the relationship of fast vs slow powder on weight of bullet and/or length of barrel. Any issues of loading up same grain weight with fast powder instead of slow? Or its a more trial and error approach.

[Dogue]

Powder is harder to find everywhere so you're not alone out there on the islands.

Your best bet is to see where the "other" powder falls on a burnrate chart compared to "known" powders...then if you find one that's close check here to see if anyone has any experience with it. Most of the available powders have likely been tried by some on here already and it can save you some headaches, and money, to ask here first. Unfortunatly, just because a powder shows on the chart as being right next to a powder that works doesn't mean it will also do well in a Grendel.

Oh, and check a few different burnrate charts since they rarely agree with each other (a sign that shows what an in-exact science burnrates are).

[JASmith]

Also, there are couple of good search functions to use when you are curious about a specific powder. I did a search on "8208" using the "Advanced Search" button and turned up about a dozen hits, one which was:

Powder Burn Rate effects

You can also try the Google Custom Search Engine set up by Drifter.