8 twist 22” 300 Win Mag with 215 Berger Hybrids

Looks like a good plan to me. Youre essentially building a 26" 30-06 (slightly more energy) but with a much shorter over all rifle length.

I did the same thing with my 7mm rem mag. Have a TBAC ultra 9. Chopped my sendero down to 18" because of not being able to get a rifle over 5ft long in and out of a vehicle with any sort of a hurry.

In the end, I lost about 300fps with the 180 hybrids which hurt but the handiness of the rifle was back and the shots are still incredibly quiet compared to before....

Ballistically im on par with a hot 308 (wind drift is significantly better however) but being able to road hunt and jump out of the vehicle in a flash on whitetails has been very much worth it. Especially if a shot next to the vehicle happens. I went to the extreme end and lost about 40fps per inch. The 300wm would likely lose about as much. I plan to step down to the 162 ELDX once i get a load dialed in. Factory 162 ELDx ammo has shown promise too. Velocity will get better but energy will stay about the same. I have around 900lbs of energy at 1k. Good enough! Heres a pic of it. It gets the job done.

johnlittletree said:

Maybe you should consider a 30-06 in that same set-up. You have to really dial back the load from a barrel that short in a magnum. The fireball at the end of the barrel is going to be huge at times when you are not running your can! A load that worked great in my 26 in barrel had too much flash in a 22 inch barrel. Daytime might be fine but at Nautical Twilight it will be blinding. In fact I was shooting over the roof of my car at the time. The 26 inch barrel golden the 22 inch left scorch marks in the paint of the car.

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This depends on the specific powder used more than the barrel length. I can burn 75gr of H4350 or H100-v in an 18" barrel with minimal muzzle flash and 140gr of H50BMG with less muzzle flash than most 26" 300 Win Mags using any powder. Some powders just produce less muzzle flash than others, and it's not dependent on burn rate.

WildRose said:

True, in order to get better velocities from shorter barrels you have to go to faster burning powders. The problem with that is when you are trying to push heavy for caliber bullets you pressure out very quickly with faster burning powders.

If you're going to go with a short barrel in the 18-22" range you'd be better off going with lighter bullets so you can keep velocities up or by going with a lower volume case to start with.

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Under what circumstances are you seeing these results? I know we've gone round and round on this before, but in all my work with short barreled (17-20") specialty pistols chambered for magnum rifle cartidges this has never been true. What specific cartridges/barrel lengths were you using and what powder/bullets were you using?

To the OP, just cut the barrel to whatever length you want and have fun. Unless you're really looking to hunt out past 800 yards I doubt you'd notice the difference.

yorke-1 said:

This depends on the specific powder used more than the barrel length. I can burn 75gr of H4350 or H100-v in an 18" barrel with minimal muzzle flash and 140gr of H50BMG with less muzzle flash than most 26" 300 Win Mags using any powder. Some powders just produce less muzzle flash than others, and it's not dependent on burn rate.



Under what circumstances are you seeing these results? I know we've gone round and round on this before, but in all my work with short barreled (17-20") specialty pistols chambered for magnum rifle cartidges this has never been true. What specific cartridges/barrel lengths were you using and what powder/bullets were you using?

To the OP, just cut the barrel to whatever length you want and have fun. Unless you're really looking to hunt out past 800 yards I doubt you'd notice the difference.

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Any of them. In order to achieve similar velocities with shorter barrels you have to go to faster burning powders all of which will pressure out before slower burning powders. That is the whole point of coming up with the slower burning powders to begin with, to attain higher velocities with lower max pressures by taking advantage of the longer barrels. The longer barrel allows for more burn time giving you increased velocities without excess pressures when comparing faster/slower burning powders.

That's always been my experience, thought process, and way I was taught it worked as well, wildrose.

I'm not sure how it would serve someone to load a large charge of slow powder in a short barreled rifle to bring up pressure and velocity to the same level attainable with a faster (but still relatively slow) powder in that same short barreled rifle, while spitting a good percentage of the slow powder out of the muzzle unburned. Not very powder efficient, cost efficient, or seemingly wise.

Out of curiosity over this, I ran the numbers Using Quick load for reference on powders mentioned using a 20" barrel on a hypothetical 300 win mag.

69 grains H4350 gives 2642 fps with a 215 Berger, max pressure 63k and muzzle pressure 14393 psi out of a 20" barrel with a ballistic efficiency of 27%.
Amount of propellant burned is 99.96%.

Conversely it takes 72.5 grains of H4831SC to give 2627 fps with a 215 berger, max pressure 59k and muzzle pressure 15,296 psi out of a 20" barrel with a ballistic efficiency of 24.5% Amount of propellant burned is 98.3%

In the extreme case of using H50BMG, it would take 86.5 grains at 12% compression to give 2635 fps with a 215 Berger, max pressure 58k and muzzle pressure is 16,843 psi out of a 20" barrel with a ballistic efficiency of 20%. Amount of propellant burned is 85%.

That's about 13 grains of powder going out the end of the barrel unburned, not to mention the waste of using 86.5 grains of H50BMG to do what 69 grains of H4350 will do. That's another 17.5 grains of powder wasted, bringing the total up to 20.5 grains of wasted powder.

The reason you're not seeing a large muzzle flash with the slower burning powders in the short barrels is because once that unburned solid powder hits the muzzle, you are extinguishing the flame front. It's not a gas.

wildcat455 said:

That's always been my experience, thought process, and way I was taught it worked as well, wildrose.

I'm not sure how it would serve someone to load a large charge of slow powder in a short barreled rifle to bring up pressure and velocity to the same level attainable with a faster (but still relatively slow) powder in that same short barreled rifle, while spitting a good percentage of the slow powder out of the muzzle unburned. Not very powder efficient, cost efficient, or seemingly wise.

Out of curiosity over this, I ran the numbers Using Quick load for reference on powders mentioned using a 20" barrel on a hypothetical 300 win mag.

69 grains H4350 gives 2642 fps with a 215 Berger, max pressure 63k and muzzle pressure 14393 psi out of a 20" barrel with a ballistic efficiency of 27%.
Amount of propellant burned is 99.96%.

Conversely it takes 72.5 grains of H4831SC to give 2627 fps with a 215 berger, max pressure 59k and muzzle pressure 15,296 psi out of a 20" barrel with a ballistic efficiency of 24.5% Amount of propellant burned is 98.3%

In the extreme case of using H50BMG, it would take 86.5 grains at 12% compression to give 2635 fps with a 215 Berger, max pressure 58k and muzzle pressure is 16,843 psi out of a 20" barrel with a ballistic efficiency of 20%. Amount of propellant burned is 85%.

That's about 13 grains of powder going out the end of the barrel unburned, not to mention the waste of using 86.5 grains of H50BMG to do what 69 grains of H4350 will do. That's another 17.5 grains of powder wasted, bringing the total up to 20.5 grains of wasted powder.

The reason you're not seeing a large muzzle flash with the slower burning powders in the short barrels is because once that unburned solid powder hits the muzzle, you are extinguishing the flame front. It's not a gas.

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I believe you just proved that a slower powder in a short barrel will give you more velocity. Run your H4831sc load up to 63k psi. At 59k you are almost matching the velocity of H4350. I think you eventually could get higher velocity with a faster powder, your barrel length would just need to be at an extremely short length.

Going off my research of 1 (not really a quantifiable number, but all I've got). Running heavy bullets in my 300blk pistol at the highest attainable velocities. 150gr Speer gd BLK in a 7.5" pistol trying to achieve the highest velocity possible for a short range hunting cartridge. With H110 which is known for producing some of the highest velocities with lighter bullets I was able to reach 1775fps before pressuring out. Switching over to CFE BLK which is a much slower powder, I was able to achieve 1850fps before pressuring out. I burned a lot more CFE BLK to do it, (over 25% more) I have unburnt powder being thrown from the end of the muzzle, it's not nearly as efficient, but I obtain a higher velocity.

I'll run the numbers later, and if you'll remember, I stated I ran H4831SC in my 22" 300 Win Mag, and it was my recommendation for a powder to use in the OP's 20" barrel. See post #24 for clarification.

I hardly consider it a slow powder. More like optimum powder.

I think you can take this slow powder thing too far, as evidenced by my hypothetical data, and I think some have.

I prefer first hand experience to computer models, but Quickload won't help the fast powder argument. These were all done using factory presets in Quickload with the exception of the internal case capacity which I adjusted to match my once fired Winchester brand 300 Win mag brass. I chose to use 3.600" for the OAL since that will likely be more representative of the gun being built than using the SAAMI spec 3.400". All loads were adjusted to be as close as possible to the max pressure spec of 64K psi. H1000 was used for the slow powder and H4350 was used as the fast powder. I chose two Hodgdon powders in order to limit differences caused by drastically different powder compositions. Barrel lengths used are 26" and 20".

26" barrel results




20" barrel results



I'll admit, H1000 is only getting a 99.8% burn in the 20" barrel in this model. I don't know that I'd really call that significant though. Then again I don't drive a Prius and worry about fuel economy; I'm more interested in performance.

yorke-1 said:

I prefer first hand experience to computer models, but Quickload won't help the fast powder argument. These were all done using factory presets in Quickload with the exception of the internal case capacity which I adjusted to match my once fired Winchester brand 300 Win mag brass. I chose to use 3.600" for the OAL since that will likely be more representative of the gun being built than using the SAAMI spec 3.400". All loads were adjusted to be as close as possible to the max pressure spec of 64K psi. H1000 was used for the slow powder and H4350 was used as the fast powder. I chose two Hodgdon powders in order to limit differences caused by drastically different powder compositions. Barrel lengths used are 26" and 20".

26" barrel results

20" barrel results

I'll admit, H1000 is only getting a 99.8% burn in the 20" barrel in this model. I don't know that I'd really call that significant though. Then again I don't drive a Prius and worry about fuel economy; I'm more interested in performance.

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Is there any barrel length where the faster powder would over take the slower one? This being theoretical since it's quickload, but fairly accurate.

Gord0 said:

Is there any barrel length where the faster powder would over take the slower one? This being theoretical since it's quickload, but fairly accurate.

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There might be, but even with a 10" barrel H1000 beats H4350. This is good data to have though in case anyone wants to build an AR pistol using one of the Nemo Omen 300 Win Mags!

yorke-1 said:

There might be, but even with a 10" barrel H1000 beats H4350. This is good data to have though in case anyone wants to build an AR pistol using one of the Nemo Omen 300 Win Mags!

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Haha, 300blk pistol conversion begins. Thanks for the info yorke-1!

Did these builds come to fruitation? Any velocities with 215s and h1000 In 22 to 25" barrels?