18-20" 300 RUM: change my mind..

[Ernie]

If you make claims about short barrel performance don't mention straight wall cases and revolvers.
We are talking high pressure rifle cartridges in short barrels

14.5" 308 Winchester with Factory TAP 168's at 2375 fps
15.9 308 Winchester with reloads 155 A-Max @ 2555 fps. H-4895
My 308 Winchester F-TR rifle 30" barrel with 200.20x at 2630 fps
15.75" 7.82 Patriot ( Bigger than a 300 WSM) 150 NBT at 3001 fps and the 180 SGK at 2750 fps.
18" 300 RUM 230 grain Berger Retumbo at 2825 fps

Any questions?

 

[simmonzz]

I see more unburned powder in a 45-70 barrel after each shot than I've ever seen from a short barreled magnum.

I've taken the short barrel magnum concept to the extreme, and I know Ernie has as well. I've never really seen the increase in muzzle flash, or any unburned powder flying out of the barrel. Just for fun, this video compares the same load in a 30" barrel and a 20" barrel. These guns are both shooting 140gr of H50bmg and a 300gr OTM. There aren't a lot of powders out there slower than H50bmg, so this is a pretty good test of the short barrel/slow powder myth.



Here's a less extreme example, but still a good one. This is 76.5gr of H4350 behind a 250gr bullet from an 18" barrel. The muzzle flash really isn't that significant.



I'll bring a big white sheet the next time I bring out the 338/408 Improved pistol. I might need to bring 10-15 tent stakes to try and hold the sheet down, but I'll lay it out in front of the muzzle to see if there's any unburned powder on the ground. I've never done that, so it's a good idea for a test.

I don't personally even see the muzzle flash point as an argument.. not like I'm trying to conceal my position. I'm shooting a f-ing magnum with a 5 port brake for Christ sake lol. Muzzle flash is incredibly temporary and as long as my dope is good the animal should go down regardless if there's flash or not. From a military stand point I can see the muzzle flash argument but not for hunting or long range hunting even for that matter.

 

[Ernie]

I see more unburned powder in a 45-70 barrel after each shot than I've ever seen from a short barreled magnum.

I've taken the short barrel magnum concept to the extreme, and I know Ernie has as well. I've never really seen the increase in muzzle flash, or any unburned powder flying out of the barrel. Just for fun, this video compares the same load in a 30" barrel and a 20" barrel. These guns are both shooting 140gr of H50bmg and a 300gr OTM. There aren't a lot of powders out there slower than H50bmg, so this is a pretty good test of the short barrel/slow powder myth.



Here's a less extreme example, but still a good one. This is 76.5gr of H4350 behind a 250gr bullet from an 18" barrel. The muzzle flash really isn't that significant.



I'll bring a big white sheet the next time I bring out the 338/408 Improved pistol. I might need to bring 10-15 tent stakes to try and hold the sheet down, but I'll lay it out in front of the muzzle to see if there's any unburned powder on the ground. I've never done that, so it's a good idea for a test.

 

[Wedgy]

The powder is burnt but the gas is still expanding yielding higher velocities in longer barrels. You short magnum guys are fighting a battle against the traditional long barrel crowd that has not tried what you guys have proved to be the case.
When CA allows suppressors I will go that route also.
On the other hand you may be responsible for the powder shortage. LOL

 

[simmonzz]

The powder is burnt but the gas is still expanding yielding higher velocities in longer barrels. You short magnum guys are fighting a battle against the traditional long barrel crowd that has not tried what you guys have proved to be the case.
When CA allows suppressors I will go that route also.
On the other hand you may be responsible for the powder shortage. LOL

You don't need a can to reap the benefits of a shorter stick. Just ask my girlfriend lol

 

[7.62 Gunner]

You guys are killing me
I'm bottle feeding the baby while scrolling through the responses, my wife's rolling her eyes while I sit here giggling to myself

 

[Ernie]

You short magnum guys are fighting a battle against the traditional long barrel crowd that has not tried what you guys have proved to be the case.
On the other hand you may be responsible for the powder shortage. LOL

Been using short barrels since the 80's.
The actual MV numbers of short barrels have long been proven.
The accuracy potentials of short barrels at short and long range have been proven.
I am not sure I want to take responsibility for the powder shortage

 

[North Idaho Hunter]

Good to know, you're talking worked over for the UM 3.95 mags right?
If you're in North Idaho I'm not too far south of you

Yessir!
We send all of ours to Justin linenbach of kinport peak rifles in Pocatello. He does a fantastic job with quick turnaround time!

 

[7.62 Gunner]

So I got my 300 RUM ADG brass today and loaded up two 225 eldm dummy rounds, one at 3.840 to cycle in my 3.850 BDL mag and another at 3.940 to simulate a 3.950 DBM box.
My question is what if anything am I going to gain by modifying my anTi action to seat them out an additional .100 ??
Here they are with a 225 to show how deep they're seated

 

[simmonzz]

So I got my 300 RUM ADG brass today and loaded up two 225 eldm dummy rounds, one at 3.840 to cycle in my 3.850 BDL mag and another at 3.940 to simulate a 3.950 DBM box.
My question is what if anything am I going to gain by modifying my anTi action to seat them out an additional .100 ??
Here they are with a 225 to show how deep they're seated
View attachment 400990

Chase the lands longer without needing the barrel setback? Maybe a little less pressure as early on? Never really understood the need for the 3.950 until you get into the even longer oal chamberings myself. But I'm sure there's someone with more insight than me on this topic

 

[Mike D Texas]

So I got my 300 RUM ADG brass today and loaded up two 225 eldm dummy rounds, one at 3.840 to cycle in my 3.850 BDL mag and another at 3.940 to simulate a 3.950 DBM box.
My question is what if anything am I going to gain by modifying my anTi action to seat them out an additional .100 ??
Here they are with a 225 to show how deep they're seated
View attachment 400990

You get the bearing surface of the bullet at or above the neck/shoulder junction where donuts can form and cause issues.

If you aren't stuck on using a DBM, Wyatt's sells a 4" center feed internal box that would move you up just a bit more. You are still slightly below the n/s junction even seated at 3.940.

 

[7.62 Gunner]

You get the bearing surface of the bullet at or above the neck/shoulder junction where donuts can form and cause issues.

If you aren't stuck on using a DBM, Wyatt's sells a 4" center feed internal box that would move you up just a bit more. You are still slightly below the n/s junction even seated at 3.940.

I've never had any issues with the bearing surface seated into the base of the neck, I've only had donuts form when necking down.
I also use expander mandrels so maybe that helps..
I'm more curious if the slightly longer length will make any performance difference

I had a wyatts cfe9 center feed in the past and I've never hated a magazine set up more than that PITA.

 

[436]

I'm running a 24" 30 Nos that I'm head over heals for, except that it's stupid frigging long with my Nomad LT suppressor.
The suppression and recoil reduction is amazing to the point that I refuse to ever put the brake back on.
Soo I'm looking to go with a short barrel and continue the suppressed goodness with 225 eldms around 2800 fps.
I don't buy into the "Efficiency" crap, and 700-1000 rounds will take me 4-5 years of shooting.
I have a 3.850 mag box
What do you all think?

And please for the love of Jesus don't recommend a 30 Sherman Mag...

18" or 20" barrel with that load? Sounds like a waste of powder to me, and something of a drop in performance. But! hey, that's what fun guns are all about, doing your thing.
Just my 0.2 Cheers

 

[QuietTexan]

I'm more curious if the slightly longer length will make any performance difference

Negligible, nothing that trying multiple powders can't overcome. It's a huge case and full capacity isn't actually used by most powders. Retumbo, 7828SSC, Magnum, H1000, RL33 and LRT all book at less than 100% load density in SAAMI COL of 3.600" using bullets from 180gns and up, meaning you won't be using the case volume you're losing to seating the bullet at 3.840 vs 3.940.

My 300 RUM shoots certain things fine stuffed down, specifically 210 AccuBond LRs. Worst case if the 225 ELD sucks change the bullet out.