Been looking at what powder to use with these two new to me cartridges.  For the 6.5 H4350 seems to get the nod, but is not listed for the 6mm in the references I have. I have to look a little more on the 6mm to see what all is being used.  From my Hornady manuals and data it seems that for 140+ 6.5 projectiles and 103-108 6mm projectiles that I plan on sticking with have RL-17 in common.  Both have good velocities from the data and it would be nice if the two could use the same powder.

In the end I know I'll try out a few to find what works for each cartridge in which rifle,  but it would be nice if it works for both.

Anyone have info or experiences on using RL-17 in one,  the other or both? Case fill, velocities,  what primers used? I'll be using Hornady brass as I have worked up a good amount of once fired in both,  so they are large rifle primers.

Thanks in advance.

A buddy uses RL-17 in his 6.5CM with the 14Xgr bullets and does so because of the increased velocity.

Having said that, I use H4350 in my 6.5x47L as it's much more temp stable than RL-17 and the velocity change due to temp change is not something I want. I have read, but have no personal experience, that RL-16 is in the same velocity range as H4350 and much more temp stable than RL-17.

Just food for thought.

I load it for my 6.5 RPR.

RL-17
140eld match
Win LR primer
Hornady brass(fired)

39.4 is my best “soft load”
41.2-41.3 my best full load.

Good info,  thank you.

The fact. Test is horn America gunner 140.

It’s the best factory ammo I’ve used in my RPR. The second target opened up on it, turns out the suppressor needs to be tight . Lucky I didn’t have a baffle strike.

To add, I’m using Redding type s sizing with bushing and comp seating die.

I use H4350 for both my 260 Rem and my 6XC.

One really good thing about H4350, it's part of Hodgdon's EXTREME Series (insensitive to temperature).

I have tried Ramshot HUNTER as a substitute for H4350 (same burn rates) and it was perfectly satisfactory.  It meters better than 4350, too, as it is a ball powder.

I will be trying Ramshot MAGNUM next.  It is slower than H4350 and slower than HUNTER which be a good thing if you have the barrel length to use it (longer barrel life, slightly higher velocity).

Get a burn rate chart.  Look for H4350 and look for other powders in the same burn rate range.  The Alliant ReLoader series is mentioned above.  There are Vitavouri powders, too.  Really quite a few good powders.

OST

I just bought 8lb of RL 17 to try out with 140g Nosler RDF bullets.

I figure if H4350 is unobtainium, I may as well try something available.

I was puzzled by this comment so I looked around.  It's out there.  It is not the unobtainium it was a year ago.

All good info.  I'll look up a few of these.

Both my Creedmoor's are running 22" barrels. So far I'm pretty happy/ impressed with both. I know there are other older cartridges with similar performance,  but these are what I ended up with playing with large frame AR's. One thing for sure it sure seems I've got more than a few things to investigate when going to develop some loads for these two.

I'm almost thinking now that some bolt guns chambered for these calibers could be interesting.  Don't get me wrong,  I don't hunt or shoot competitions. I'm just one that goes shooting on the weekends,  shooting to better my last outing and enjoying what I've built/developed and learned. Any day of shooting is better than any day at work.

Thank you again everyone,  great info and suggestions.

RL17 is a good powder but be aware that it doesn't like temp swings.

What might be a good load at 70' outside might be popping primers at 90'.

To me, that is the very definition of a BAD powder.  A 20 degree temperature swing that takes you from fine to unsafe,...???

Leaving your ammo in the sun will raise the temperature more than that.  Leaving a round in the warm chamber will raise the temperature more than that.

I find it hard to believe Alliant would sell such a powder.  Are you referring to loadings that are so critically high in pressure they become unsafe when the temp goes up 20 degrees?

Temp sensativity is a concern.

H4350 goes across both rounds.  I see that Superformance does as well. I haven't found too much info on others using that and I'm not familiar with it. From the burn chart it is slower than either 4350 & RL17. I'm wondering about it too. I may have to buy a small canister to check out. It is supposed to be a progressive powder,  but so is RL17.

According to the Hornady data, Superformance has a listing for a wide range of projectile weights even light projectiles for the 6mm. The listings for the 6.5mm cover 100g and heavier,  but not the lighter ranges.  Fair enough, I want to stick with 6.5's that are >= 129gr  and with the 6mm I'll stay with the 103gr or 108gr projectiles. For my other rifles I usually use Hodgdon powders (H335, CFE223). Anyone have experiences they care to share about Superformance?

I have some AR-Comp. Alliant  states it's not temp sensitive. Data available is kinda slim.  There is some for 223, 243 & 308 (308 having a pretty good weight range) from Alliant. Nothing from Hornady.  There is limited data for it in the Grendel reloading handbook. Shame because velocities that are listed don't look bad. Anyone try AR-Comp?

Oh well,  one of the other things that is great about shooting and loading. Always something to lookup, research and try to understand.  

Most of our club guys shooting 1K matches use RL17 for the velocity and adjust as needed for the weather, I stick with 4350 as I like the consistency.

Nothing is free in the long range game

True,  very true.