Reloader 26/Short Barrels

[Monteria]

Well, I shoot 180 ELDMs from an 18" 7 PRC at 2815fps with RL26.

I ran the following powders to max in my rifle and RL26 was the fastest by 100fps.

4831sc
7828
H1000
Magpro
LRT
RL26

It's not that RL26 needs more barrel. You need to push to max in your rifle, not book max, actual max, to know any powders true potential in that barrel. You proved that yourself when you found heavy bolt lift in your long barrel that you don't see in the short one.

 

[Calvin45]

Until today, I never put any stock into there being better powders for short barrels. I believed that if a listed powder was the fastest when tested in a 24 inch barrel, it would still be the quickest in a shorter tube compared to other powders.

This is not true.

I have been struggling to get velocity out of a 20 inch 300 WSM I just built. Rather than ramble, I'll give you the velocity numbers.

69 grains of reloader 26, 190 Speer Impact, is getting me 2,820 fps.

The load manual says 3,004 fps with a 24 inch barrel. I knew I would lose some velocity but not 184 fps!

So after 60 rounds of this, I finally just try a faster powder. 66.5 grains of Staball 6.5 got me 2,910 fps and less case expansion measured by a micrometer.

Hodgdons load manual says that 66.3 grains of Staball 6.5 should get me to 2,960 fps. in a 24 inch barrel with 61k psi.

So I pushed it a little past max due to a little bit of head room on the pressure and the cases are doing fine. The velocity loss from a 24 to a 20 inch tube isn't even worth mentioning.

Unless anyone with some experience here can give me a better explanation, I'm going with the faster burn rate was what made the difference.

Thanks a bunch for sharing. I know there's been no shortage of tests showing that as you cut down a barrel the powders that were fastest mv in a longer barrel continue to be the fastest as length went down.

But I've never seen rl26 data. I'd be curious about superformance and rl17 too. And to be honest the StaBall 6.5 is unconventional as well

All four of these powders have one thing in common: PROGRESSIVE BURN RATE!

It's not just that they're double base, it's that their burn rate changes, increases, over time compared to normal powders. This results in less spiky more flattened out pressure curve, less abrupt at the beginning, but maintaining higher pressure further down. It really does make sense to me that progressive burn rates would therefore suffer disproportionate velocity loss compared to static burn rates

Interesting.

 

[AZ82New]

Thanks a bunch for sharing. I know there's been no shortage of tests showing that as you cut down a barrel the powders that were fastest mv in a longer barrel continue to be the fastest as length went down.

But I've never seen rl26 data. I'd be curious about superformance and rl17 too. And to be honest the StaBall 6.5 is unconventional as well

All four of these powders have one thing in common: PROGRESSIVE BURN RATE!

It's not just that they're double base, it's that their burn rate changes, increases, over time compared to normal powders. This results in less spiky more flattened out pressure curve, less abrupt at the beginning, but maintaining higher pressure further down. It really does make sense to me that progressive burn rates would therefore suffer disproportionate velocity loss compared to static burn rates

Interesting.

If I tried N560, which is slower than the 4350 class of powders that SB 6.5 is in, I should also see a wider discrepancy than H4350 or SB 6.5 IF it's due to burn rate.

If it has to do with progressive burn rate (a concept I am not familiar with), it would reveal that too.

If I can find the time, I'll try it. SB 6.5 is doing pretty good for me so I'm probably just going to land there.

 

[AZ82New]

Well, I shoot 180 ELDMs from an 18" 7 PRC at 2815fps with RL26.

I ran the following powders to max in my rifle and RL26 was the fastest by 100fps.

4831sc
7828
H1000
Magpro
LRT
RL26

It's not that RL26 needs more barrel. You need to push to max in your rifle, not book max, actual max, to know any powders true potential in that barrel. You proved that yourself when you found heavy bolt lift in your long barrel that you don't see in the short one.

Maybe, but I was also measuring a fair amount of case head expansion in the 20 inch barrel. I could tell I was pushing near the top already.

 

[Calvin45]

If I tried N560, which is slower than the 4350 class of powders that SB 6.5 is in, I should also see a wider discrepancy than H4350 or SB 6.5 IF it's due to burn rate.

If it has to do with progressive burn rate (a concept I am not familiar with), it would reveal that too.

If I can find the time, I'll try it. SB 6.5 is doing pretty good for me so I'm probably just going to land there.

For sure, if it ain't broke don't fix it!

 

[highfinblue]

If I tried N560, which is slower than the 4350 class of powders that SB 6.5 is in, I should also see a wider discrepancy than H4350 or SB 6.5 IF it's due to burn rate.

If it has to do with progressive burn rate (a concept I am not familiar with), it would reveal that too.

If I can find the time, I'll try it. SB 6.5 is doing pretty good for me so I'm probably just going to land there.

I'm running SB 6.5 in two rifles, only tried it in two rifles, 6.5 CM, 22-250, and both are capable of the best groups I've ever shot with great velocity. I may have already shared this and if I have I apologize, but I'm interested in trying it in other cartridges. Maybe place for another thread, but what cartridges have people tried it in with success?

 

[AZ82New]

I'm running SB 6.5 in two rifles, only tried it in two rifles, 6.5 CM, 22-250, and both are capable of the best groups I've ever shot with great velocity. I may have already shared this and if I have I apologize, but I'm interested in trying it in other cartridges. Maybe place for another thread, but what cartridges have people tried it in with success?

280 AI
6.5 Creedmoor
300 WSM

If you see load data with H4350, Hunter, H100v, reloader 16, 17 or N550…….its going to work in that cartridge.

I got great velocity and accuracy out of the 280 ai but the SD was atrocious. There was a lot of empty space in that case.

For me it has worked best when the case is very full. So the 280 ai, h100v or Hunter were comparable in velocity but with much better extreme spreads du to the loads being slightly compressed.