Shorty bolt gun handloaders, powder question.

[BJames]

So, I was in a discussion with a dude, about using faster burn rate powders in shorty 16-18” rifles, specifically bolt guns. His stance was to move to a faster burn rate powder for a given bullet after having the barrel chopped, to get a more complete burn and regain some speed. I’ve never heard that before, but have never looked into it either. Initially I called bullshit, but knowing all the voodoo hoodoo shenanigans surrounding handloading, now I’m scratching my head thinking maybe…

My experience with shorty’s is exactly 1, and I just had it done. This rifle shoots just as well at 17” with the old load as when the barrel was at 24”, ended up losing about 23 fps per inch as expected.

What say you?

 

[Maurygold]

A faster burning powder will give you more velocity. H4350 Vs H1000 can give you more speed although somewhat marginal. Go to the hodgdon reloading website and check it out.

Hodgdon Reloading Data Center – The Brand Thats True

www.hodgdonreloading.com

 

[acudaowner]

maybe a different powder might pick up the speeds if you wanna go faster or slower ?

 

[Gustav7]

Every situation is different but I would say this is far from voodoo. I've talked to a lot of guys that have run shorties, and generally, a lighter bullet and a faster powder yield better results. So the 120-130 class bullet with something like Varget in 6.5cm.

The same applies to the opposite. When I load 357 mag in my lever guns, I switch to a slower powder that generally does not do as well in revolvers or stubbies. 300-MP specifically is like RL26 in the lever rifles.

Here's a video that explained it well for me from a reputable company.

 

[Cascade Hemi]

So, I was in a discussion with a dude, about using faster burn rate powders in shorty 16-18” rifles, specifically bolt guns. His stance was to move to a faster burn rate powder for a given bullet after having the barrel chopped, to get a more complete burn and regain some speed. I’ve never heard that before, but have never looked into it either. Initially I called bullshit, but knowing all the voodoo hoodoo shenanigans surrounding handloading, now I’m scratching my head thinking maybe…

My experience with shorty’s is exactly 1, and I just had it done. This rifle shoots just as well at 17” with the old load as when the barrel was at 24”, ended up losing about 23 fps per inch as expected.

What say you?

Your dude is right.

 

[SkyScrapin]

My experience on this topic with ultra short barrels has proven that faster is better if you desire a small gain in performance via velocity, pushing your transonic range out further.


Double edged sword if you go to fast a burn rate and too light a projectile tho,

When I tested 308W 12" loads, my results were as follows:

135g SMK with H332 gave decent accuracy, but crazy SDs and lack-luster downrange performance. What I concluded is the bullet wasn't heavy enough to get a near complete burn in such a short barrel causing velocity issues. H332 was the right powder, but 135g SMKs weren't the right projectile. Velocity was 2700+ FPS.

When I moved to a 155g Hybrid, it created a significantly better burn which was noticeable to the shooters ear even. SDs improved dramatically and downrange performance was there. Velocity was 2600 FPS.

I didn't move to 175g SMKs because I didn't feel I'd gain much benefit. I'd imagine 2400-2500fps would be close.

If I were to load for my 12" 6.5 CM barrel, I'd look good and hard at the 130 Hybrid and 8208 or Varget powders. Maybe even something a tad faster. In this rifle, my factory Berger Ammo 140g Hybrids are moving at 2450fps with stellar accuracy. No idea what powder they use. I'd expect to push a 130g Hybrid to 2600fps with the right powder while staying away from crazy pressure.

Preston

 

[Supersubes]

So, I was in a discussion with a dude, about using faster burn rate powders in shorty 16-18” rifles, specifically bolt guns. His stance was to move to a faster burn rate powder for a given bullet after having the barrel chopped, to get a more complete burn and regain some speed. I’ve never heard that before, but have never looked into it either. Initially I called bullshit, but knowing all the voodoo hoodoo shenanigans surrounding handloading, now I’m scratching my head thinking maybe…

My experience with shorty’s is exactly 1, and I just had it done. This rifle shoots just as well at 17” with the old load as when the barrel was at 24”, ended up losing about 23 fps per inch as expected.

What say you?

He’s right, but its hair splitting for sure. Just imagine to yourself whats happening with a slow vs fast powder, in a long barrel. The fast powder is getting the lions share of its work done a little earlier. The reality is that even with a slower powder, peak pressures come very early, say 10-12” down the barrel. The actual difference at the end of the day is pretty small, and the right answer, as always, is to pick the one that shoots best.

 

[CaptArab]

My personal take is that people way overthink this. A good 24" load is a good 16" load in my book.

 

[BJames]

He’s right, but its hair splitting for sure. Just imagine to yourself whats happening with a slow vs fast powder, in a long barrel. The fast powder is getting the lions share of its work done a little earlier. The reality is that even with a slower powder, peak pressures come very early, say 10-12” down the barrel. The actual difference at the end of the day is pretty small, and the right answer, as always, is to pick the one that shoots best.

Makes sense when I think about it in those terms. Where I got hung up was, where in the barrel are the peak pressures? But at this point, the question is answered, it’s not worth it me to chase whatever perceived performance increase. Thanks for the response

 

[BJames]

My experience on this topic with ultra short barrels has proven that faster is better if you desire a small gain in performance via velocity, pushing your transonic range out further.


Double edged sword if you go to fast a burn rate and too light a projectile tho,

When I tested 308W 12" loads, my results were as follows:

135g SMK with H332 gave decent accuracy, but crazy SDs and lack-luster downrange performance. What I concluded is the bullet wasn't heavy enough to get a near complete burn in such a short barrel causing velocity issues. H332 was the right powder, but 135g SMKs weren't the right projectile. Velocity was 2700+ FPS.

When I moved to a 155g Hybrid, it created a significantly better burn which was noticeable to the shooters ear even. SDs improved dramatically and downrange performance was there. Velocity was 2600 FPS.

I didn't move to 175g SMKs because I didn't feel I'd gain much benefit. I'd imagine 2400-2500fps would be close.

If I were to load for my 12" 6.5 CM barrel, I'd look good and hard at the 130 Hybrid and 8208 or Varget powders. Maybe even something a tad faster. In this rifle, my factory Berger Ammo 140g Hybrids are moving at 2450fps with stellar accuracy. No idea what powder they use. I'd expect to push a 130g Hybrid to 2600fps with the right powder while staying away from crazy pressure.

Preston

That’s great info, I’m kinda surprised in the velocities you’re seeing with barrels that short, faster than I would expect. The conversation I was in was specifically moving to a faster powder using the same projectile In the shorter barrels. Pretty nit picky, I know. I’ve played around with moving to lighter bullet weights (less bearing surface) and noticed they definitely preferred faster powders to see peak performance, that was in 24-26” tubes though. I’ve also watched a bunch of the barrel chop/velocity test videos over the years and assumed the velocity loss was fairly uniform, at least to a point. I wish I had the time to test everything I want to…

 

[BJames]

He is right when using a faster powder paired with a lighter bullet correct? Using a faster powder with the same heavy bullet would likely result in less velocity before pressure wouldn’t you say?

The question was same bullet, faster powder. More specifically; 18” 7 Saum, 180 Berger hybrid. Switching from H4831sc to H4350 to regain some speed.

 

[wade2big]

The question was same bullet, faster powder. More specifically; 18” 7 Saum, 180 Berger hybrid. Switching from H4831sc to H4350 to regain some speed.

I’m betting that won’t happen and just the opposite would, but maybe I’m wrong. The powder showing the best velocity with a given bullet at a long barrel length should do the same with the same bullet in a shorter barrel.

 

[BJames]

I’m betting that won’t happen and just the opposite would, but maybe I’m wrong. The powder showing the best velocity with a given bullet at a long barrel length should do the same with the same bullet in a shorter barrel.

Read post #7, Supersubes did a good job of laying it out. I thought the same thing, but now it makes sense. Might see small gains if any, not enough for me to chase down more components and do another load development.

 

[Cascade Hemi]

The question was same bullet, faster powder. More specifically; 18” 7 Saum, 180 Berger hybrid. Switching from H4831sc to H4350 to regain some speed.

You'll more likely run into pressure with that combination that find faster speeds with H4350. Generally a lighter bullet would work better assuming you aren't insisting on killing large game at a preposterous distance. 18" is short but it isn't that short.

 

[BJames]

You'll more likely run into pressure with that combination that find faster speeds with H4350. Generally a lighter bullet would work better assuming you aren't insisting on killing large game at a preposterous distance. 18" is short but it isn't that short.

That’s what I thought, for both of your statements. This discussion was centered around hunting rifles, where impact velocities/energies are of concern. That said, a 18” 7 saum is still a 6-700 yard hunting round with pretty much any 162/168 and up class of bullet, depending on a guys preference on the down range numbers. I now have a 18” 7 Saum build in the works.

At the end of the day, the load that shoots best is what’s going in the rifle. The yardage will be dictated by whatever speed the load combo makes.

 

[Doom]

I shoot 168 SMK in a 20" barrel. and I've used or tested powders from Benchmark to 2000MR. If you desire velocity then the very slow 2000MR would be the powder but it takes a lot because the powder doesn't burn out and you have a fire breathing demon on your hands. Faster burning powders seem to be more accurate and tamer on muzzle flash but at the expense of velocity. If I were hunting and going for distance I might well go for the 2000MR but for range shooting and accuracy I use N135, IMR 8208 and 4064. Anyway, that's my take.

 

[x47mike]

Quickloads...95 percent burn rate....best money you can spend. JMO Most powder in a 6bra will burn in the 9 to 12 inch range at 95 percent.
Unlike Varget, RL 15 and H4895. H4350 will hit the 95 burn rate at around 20 inches. Same velocity...2950 range
Which would you go with and why?