30X357 magnum

Elvis · Posted: Wed Apr 18, 2018 3:19 am Post subject: Re: 30X357 magnum

just picked up your comment re noise...... what powder are you using ??? and is that amount of noise or lack thereof with muzzle brake or with a suppressor???

slimjim · Posted: Wed Apr 18, 2018 3:53 am Post subject: Re: 30X357 magnum

Here is the link to a thread on subsonic performance.

www.huntingnut.com/ind...410#156410

Deer Sniper · Super Member Joined: Apr 26, 2007 Posts: 539

Elvis,

yes, I am fully aware of how easy and fast these sub-sonic rounds "ricochet" and especially more so with the heavier bullets...

slimjim · Posted: Wed Apr 18, 2018 6:45 am Post subject: Re: 30X357 magnum

I'm not aware. How is it easier for a subsonic bullet to ricochet than for a supersonic bullet?

Deer Sniper · Super Member Joined: Apr 26, 2007 Posts: 539

Elvis wrote:

just picked up your comment re noise...... what powder are you using ??? and is that amount of noise or lack thereof with muzzle brake or with a suppressor???

Elvis,

I am using Unique powder with Hornady's 208 gr. A-MAX bullet in the "baby rifle" shown in the start of this thread...

My muzzle brake is permanently attached to the barrel, and the quietness is with the muzzle brake...

I just came in from shooting 5 rounds over the chronograph, and they clocked in at the following velocities -

1,020 fps

1,022 fps

1,029 fps

1,027 fps

1,022 fps

I shot this gun both with and without the muzzle brake, and with sub-sonic loads, it is actually a little bit quieter WITH the muzzle brake! Why it is, who knows?!?!

Shooting 110 to 130 grain bullets over 2,300 fps though, it does have a "bark" to it, but not overly bad considering the small amount of powder in those loads using Winchester 296 powder...

Deer Sniper · Super Member Joined: Apr 26, 2007 Posts: 539

slimjim wrote:

I'm not aware. How is it easier for a subsonic bullet to ricochet than for a supersonic bullet?

Slimjim,

me personally, referring to the Hornady 208 gr. A-MAX specifically, shooting "targets" on the ground from a standing position, off-hand, those bullets are not traveling fast enough to penetrate into the ground like what it normally does, when driven at high velocity. Since I very seldom shoot sub-sonic rounds past 100 yds., it is easy to hear those bullets bounce through the trees, after it ricochets off the ground. Not every bullet does this, but it happens enough that you are always aware of it...

PaulS · Posted: Wed Apr 18, 2018 3:07 pm Post subject: Re: 30X357 magnum

So you use a 357 case necked to 30 caliber...
To get 1020+ fps with a 208 grain bullet you have got to be getting some high pressures.
I shoot 140 357 bullets using 19.1 grains of H110 and get a bit over 1680 from my six inch revolver. Granted you have a longer barrel but it is also less bullet base area and you are using a faster powder. It would seem to me that your loads are pushing 55000 psi or more.
With your rifle that would not be out of place but the cartridge is designed for 45000 psi.
Do you have any idea what your chamber pressures are?

slimjim · Posted: Wed Apr 18, 2018 3:22 pm Post subject: Re: 30X357 magnum

Paul, in the case of a 300 BO (similar the 30-357), all the Hodgdon powders listed for the 208gr are less than 1/2 the pressure of 55K psi.

The pressure is so low, I'm having trouble getting my subsonic loads to cycle with a carbine gas even with a suppressor.

PaulS · Posted: Wed Apr 18, 2018 3:33 pm Post subject: Re: 30X357 magnum

I realize that the amount of gas is reduced and the pressure bleeds away fast but I bet the maximum chamber pressures are real high, they just don't stay high for long.

Deer Sniper · Super Member Joined: Apr 26, 2007 Posts: 539

PaulS wrote:

So you use a 357 case necked to 30 caliber...
To get 1020+ fps with a 208 grain bullet you have got to be getting some high pressures.
I shoot 140 357 bullets using 19.1 grains of H110 and get a bit over 1680 from my six inch revolver. Granted you have a longer barrel but it is also less bullet base area and you are using a faster powder. It would seem to me that your loads are pushing 55000 psi or more.
With your rifle that would not be out of place but the cartridge is designed for 45000 psi.
Do you have any idea what your chamber pressures are?

I know exactly what my pressures are running! 19,100 psi

Deer Sniper · Super Member Joined: Apr 26, 2007 Posts: 539

PaulS wrote:

I realize that the amount of gas is reduced and the pressure bleeds away fast but I bet the maximum chamber pressures are real high, they just don't stay high for long.

How in the world do you figure chamber pressures "are real high"???

Maybe in other guys guns and the way they load them, but I built this specifically for LOW PRESSURE SUB-SONIC LOADS! Barrel life will literally be thousands of rounds, and with the loads I am shooting, ear plugs are NOT required!

Elvis · Posted: Thu Apr 19, 2018 12:15 am Post subject: Re: 30X357 magnum

slimjim.....do you remember stinger .22lr rounds???? they were marketed to not ricochet.... fast n fragile it hits n breaks up...subsonic it doesnt breakup in fact they barely deform so if they dont "stick into" something...well they gotts to go somewhere. the big long heavy rounds love to swap ends (as you have proven before) if they are barely stable the tendancy to tumble is increased ten fold.

PaulS · Posted: Fri Apr 20, 2018 11:14 pm Post subject: Re: 30X357 magnum

Deer Sniper wrote:

PaulS wrote:

I realize that the amount of gas is reduced and the pressure bleeds away fast but I bet the maximum chamber pressures are real high, they just don't stay high for long.

How in the world do you figure chamber pressures "are real high"???

Maybe in other guys guns and the way they load them, but I built this specifically for LOW PRESSURE SUB-SONIC LOADS! Barrel life will literally be thousands of rounds, and with the loads I am shooting, ear plugs are NOT required!

You are using a fast burning powder - Unique, heavy bullets (over 200 grains), in a small case (357 necked to 30 caliber) and getting velocities higher than I get using slower powder, lighter bullets with a larger bore.
All that adds up to higher chamber pressures for shorter duration.
Just because the loads are sub sonic doesn't mean low pressures. It just means lower average pressure under normal conditions. The same is true of the amount of noise and blast.

Aloysius · Posted: Sat Apr 21, 2018 12:36 am Post subject: Re: 30X357 magnum

PaulS, it's hard to compare a revolver with something without that gap between cilinder and barrel. I think even Lyman gives different reloading data for the same caliber used in a revolver, a Contender or a rifle. And besides that I can imagine that the sharp shoulder in this 30x357 Magnum will have it's influence. Just look at a few 6mm cartridges: the .243 Win, the 6 mm Rem and the 6 mm PPC or the 6 mm Norma BR. Or what about these new short magnums?

@Deer Sniper: what's the trick to get a bullet stabilized at subsonic and at high velocity using the same barrel (and the same twist in that barrel)? Do you run a heavy bullet at high velocity and a light bullet at low speed? Just the opposite of what 'normal' people would think?

Deer Sniper · Super Member Joined: Apr 26, 2007 Posts: 539

Aloysius,

no, I do not run heavy bullets at high velocity and no, I do not run light bullets at low velocity...

On the HEAVY side, I shoot 180 gr. Round Nose / 200 gr. Round Nose / 208 gr. A-MAX bullets at an average velocity of 1,020 fps...

On the LIGHT side, I shoot 90 gr. XTP / 110 gr. / 130 gr. @ 2,400 + fps...

A lot of guys opt for a 1-7" twist rate barrel, but I built mine on a 1-8" twist rate barrel...

The 1-7" twist rate barrels will not always fully stabilize, or actually over stabilize most of the lighter weight bullets. A 1-7 " twist rate barrel is best for HEAVYWEIGHT bullets at sub-sonic velocities, as that is their intended design and purpose...

A 1-8" twist rate seems to be a good compromise for both light AND heavy bullets, though it may not always stabilize bullets over 210 gr. in weight...

Just like my 30X357 Maximum - put it in a 1-13" twist rate barrel and you can get some of 110 gr. bullets darn near 3,000 fps.!!! Put this cartridge in a 1-7" twist rate barrel, and you defeat the whole purpose of everything! It won't do well with the lighter bullet weights, and with the heavy weight bullets, it becomes not nearly as efficient as the much smaller cartridges are...

Back to the original part of the story. Running the lighter weight bullets in my litter rifle at and above 2,400 fps., 100 yd. accuracy for any of bullets and loads I have, will consistently keep 3-shots under an inch at 100 yds. and do it day in and day out. The heavyweight bullets and loads will do the same thing at 75 yds.. I don't shoot those any further, so I don't target them any further. The lightweight bullets though, I will and do shoot them over 200 yds. quite often, and for what I use my "baby gun" for, it performs flawlessly! I cannot ask any more of it than that.