20” 6.5Creed burn rate

[Pickle Rick]

Is a 20” 6.5creed short enough to want to run lighter bullets and faster burning powders? Is it long enough to run the standard 4350’s with a pretty decent burn?

Would love to hear some 20” loads that work for you guys and velocity.

 

[mike278]

I tried that route, and yes, 130s work. I eventually ended up putting a 23" barrel on my gun and using 147s. I would suggest trying the 147s just for the bc. H4350 is the easy button. I tried 6.5 staball, RL17, and on and on. I hate to admit defeat, but there's a reason everyone is using H4350. In fairness though, I haven't tried Vihta Vouri 555. Easy to get single digit SDs with H4350 and Lapua SRP brass running CCI BR4s. Back to the OP comments, I moved from the 20" to 23" just for the MV increase. Absolutely nothing wrong with the shorter barrel. I'm a couple glasses of whiskey in, so I don't want to talk load data without my notes, but long story short, 130s and H4350 work.

 

[Pickle Rick]

130s with ~42.5gr H4350 is money

 

[stello1001]

Same powder that works on 26" barrels works on 16" barrels. Idk why people think shorter barrels work with different powders than longer barrels, etc. The short barrels will simply be slower and longer barrels faster.

 

[Pickle Rick]

Same powder that works on 26" barrels works on 16" barrels. Idk why people think shorter barrels work with different powders than longer barrels, etc. The short barrels will simply be slower and longer barrels faster.

Obviously I know they all “work”. Faster burning powders can be more efficient in shorter barrels.

 

[stello1001]

Obviously I know they all “work”. Faster burning powders can be more efficient in shorter barrels.

More efficient in short barrels compared to what, long barrels? The longer barrel will still have the higher MV.

Let's take varget for example. If we run xx amount of varget, a faster burning powder compared to h4350 (golden standard for 6.5 cm) through a 16" barrel pushing a 123 SMK, and the same amount with the same bullet in a 26" barrel, the longer one will still produce faster speeds.

 

[Pickle Rick]

More efficient in short barrels compared to what, long barrels? The longer barrel will still have the higher MV.

Let's take varget for example. If we run xx amount of varget, a faster burning powder compared to h4350 (golden standard for 6.5 cm) through a 16" barrel pushing a 123 SMK, and the same amount with the same bullet in a 26" barrel, the longer one will still produce faster speeds.

Omg yes I know longer barrels have more velocity. By efficient I mean fps/grain and not having a shit ton of unburnt powder shooting out of my muzzle. This isn’t a debate on if longer barrels are faster lol

 

[santee116]

My 6.5 CM has an 18" PBB barrel.

It shoots the 143 ELDx with RL 26 at 2750. It shoots the 130 TMK with RL-17 at 2865. It shoots the 139 Scenar with H4350 at 2700. About 1500 rounds into it, still shoots fine.

It'll work with a 20 inch tube.

 

[Pickle Rick]

My 6.5 CM has an 18" PBB barrel.

It shoots the 143 ELDx with RL 26 at 2750. It shoots the 130 TMK with RL-17 at 2865. It shoots the 139 Scenar with H4350 at 2700. About 1500 rounds into it, still shoots fine.

It'll work with a 20 inch tube.

Thanks!

 

[stello1001]

Omg yes I know longer barrels have more velocity. By efficient I mean fps/grain and not having a shit ton of unburnt powder shooting out of my muzzle. This isn’t a debate on if longer barrels are faster lol

That's fine, I get that. We're not trying to turn this into a debate of slower mv for shorter length vs faster mv for longer length, etc.

But I just don't get what you're trying to ask. Ok, varget is a faster burning powder than r16 for example. So you go to a short barrel and don't want to leave so much powder unburnt so you turn to varget, it's faster than r16 & h4350. Now what? You went to a faster burning powder but with a much shorter barrel. You probably want to go to a much slower burning powder and shove more powder into the case to make up for the lost velocity from the shorter barrel as a result. And now we're back to leaving more powder unburnt. Which from your reply, on post 7, seems to indicate is not what you're looking for.

The faster burning powder, varget in this case, is still gonna have less unburnt powder from a longer barrel still, than a slower burning powder. Really not trying to stirr shit up. Just trying to understand why every now and then, people seem to think shorter barrels need different powders to work better, etc.

The others who have commented, mentioned h4350, if that tells you anything.

 

[Pickle Rick]

That's fine, I get that. We're not trying to turn this into a debate of slower mv for shorter length vs faster mv for longer length, etc.

But I just don't get what you're trying to ask. Ok, varget is a faster burning powder than r16 for example. So you go to a short barrel and don't want to leave so much powder unburnt so you turn to varget, it's faster than r16 & h4350. Now what? You went to a faster burning powder but with a much shorter barrel. You probably want to go to a much slower burning powder and shove more powder into the case to make up for the lost velocity from the shorter barrel as a result. And now we're back to leaving more powder unburnt. Which from your reply, on post 7, seems to indicate is not what you're looking for.

The faster burning powder, varget in this case, is still gonna have less unburnt powder from a longer barrel still, than a slower burning powder. Really not trying to stirr shit up. Just trying to understand why every now and then, people seem to think shorter barrels need different powders to work better, etc.

The others who have commented, mentioned h4350, if that tells you anything.

I think it’s mostly for SD’s. Nothing more than a rule of thumb.

 

[Doom]

I think it’s mostly for SD’s. Nothing more than a rule of thumb.

Not sure where this comes from. But I have to ask what are you trying to do? If you are trying to win a drag race forget about SD and accuracy and pick a as slow a burning powder that you can pack in the case and get full pressure and you will have the highest possible velocity as you are going to get in a given barrel. You will be blowing unburnt powder everywhere and the recoil will be fun to deal with. Accuracy will be questionable because the unburnt powder can affect the bullet as it impacts the base on muzzle exit.

Now assuming you are not only interested in velocity but also accuracy then for any barrel length there is combination of bullet and powder that will optimize the potential accuracy for a given barrel length at a given specific distance based on ballistic coefficient and velocity. up to a point. Of course there are other factor affecting the combustion that also come into play.

As for SD, powders do play into standard deviation. One factor is find a powder that provides consistent combustion as the bullet is released from the case neck and engages the lands. This is a time when the volume of the chamber is increasing as the bullet moves forward but then slows down as the bullet tends to slow down momentarily as it engages the lands. Too fast a powder will likely cause pressure differences between different shots and too slow may actually allow the combustion to slow down as the bullet begins it travel.

The 308 is often referred to as a 1000yd cartridge and it can be used effectively to that distance. To do so requires a barrel longer than 20". Most rifles will be 26" or greater to effectively engage targets at that distance. A 20" Barrel? While it might be possible to reach 1000yds to do so accurately and consistanly is extremely problematic. The 20" barrel is much more of a 800 yd rifle than 1000yd.

 

[Dogtown]

If you want to get into the weeds, you can think about the time it takes the pressure curve to reach the max value in the bore. Generally you'd want to run a powder/bullet combo where the pressure peak is optimized to hit closer to the muzzle, and while the difference between a 20" and 26" may be minimal, it's conceivable that too long of a barrel would lead to the friction force starting to counteract the acceleration from pressure. And on the other end, too short of a barrel means you never hit that pressure max before the muzzle and leave a lot of velocity on the table. Of course, there's a limit to how hot/cold you can run a cartridge, so it may all be completely moot.

 

[Doom]

I ran two simulations in GRT with the 130 ELD-M. I chose to run the loads to 60KSI. It's interesting to see that in this case the H4350 almost burns out before leaving the muzzle and the velocities are close. What does happen is the recoil energy is significantly different.

In this example there is over a 1000psi difference in pressure at the muzzle.