Subsonic expansion testing

Elkins45

Elkins45

Active Member
I’ve been toying around with the idea of a slower twist barrel for 300 blackout for subsonic. I know a faster twist is needed to stabilize slower and heavier bullets but that has to be balanced against the softness of the alloy. I think sometimes the softer bullets get spun too fast and slip on the rifling.

Unfortunately I’ve never seen a blackout barrel any slower than 1:8 and I’m not willing to pay the money to experiment with a custom one.
 
P

popper

Well-Known Member
I have a 1:10 carbine, works fine with UMC factory subs, haven't tried it with cast subs. Works great for cast supers.
 
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Spindrift

Spindrift

Well-Known Member
All my .30-cal barrels at the moment are 1:10 ROT. The heaviest bullet that grouped well, with round holes at subsonic, was the Lee c309-200.

The NOE311-221 grouped well, but I didn't get to inspect the holes (digital target). The MP-BLK-GC (217grs) and PB (227 grs) also grouped well, but with oval holes.

In a couple of months, a change in Norwegian gun laws will allow me to buy two new guns. One of them will probably be a Bergara Ba13, take-down single shot, in .300 BLK with 1:8 ROT.
Intended use: FUN!
 
RBHarter

RBHarter

West Central AR
You can experiment with the Russians at 1-9ish .
I'd like to do a x39 PPC/AI in 30 . I just haven't run across a 300 barrel yet that was reasonable and not hard coated .
 
Bliksem

Bliksem

Active Member
Grumble....Grumble....I "need" a 358Win bolt gun to join this game as the 358Win autoloader can't do certain things. I got sucked into the 358 caliber rabbit-hole and am loving it so far. Soon my 358 Norma will see the light of day and another adventure will begin. I have my eye on a 308 rifle that could be a good starting point for a 358Win bolt gun but I need to get some scratch to cover the itch first. Planning and preparing for retirement looms big in any purchases...
 
CWLONGSHOT

CWLONGSHOT

Well-Known Member
waco said:
Does Ruger still make the American in .358 Win? That would be an inexpensive and appealing option for me.
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Grice is a small place in Pennsylvania. They commissioned this caliber back some years ago. I was told I bought the last one. But might be worth a call to be sure.
Im fixin to drag the Whelen outta the back a the back safe... I cast up some 352 Saecos and just need ta size and GC them. I have a couple cans a 4759 that needs shootin.
F3021161-A03F-4883-9B94-814E8206864D.jpeg11FE609D-B1DF-4857-AFA4-5B0EAB1A3560.jpeg
CW
 
Glaciers

Glaciers

Alaska Land of the Midnight Sun
JWFilips said:
I posted this awhile back on the other side of the street:
It sort of gives a look at what I have experienced with PC coating and Soft alloy over the past few years I worked with it:
Not sure if it is pertinent here but I think it fits:

I do Not Know how many of you guys ever did the egg experiment where you soak a raw egg in vinegar for a few days.
When the shell desolves, you are left with a tough rubber like coating that covers the raw ( soft) egg inside.
Now you can drop that shell-less egg on a had surface and it bounces. That protective skin is pretty tough!
Fling it against a wall and it explodes!

Now let us take a 10 BHN alloy bullet and coat it with a PC skin which some say comes in at 32 BHN! That skin is similar to what is around that egg!
It does real well going down the rifling but at impact the 10 BHN alloy takes over!
So do you see the true usefulness of PC coating now?
It is an amazing gift to all of us
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Well I missed this thread, think I was traveling at the time.. really like reading the posts here, especially Jim’s comparison of PC and the egg .
 
J

Jeff H

NW Ohio
Glaciers said:
Well I missed this thread, think I was traveling at the time.. really like reading the posts here, especially Jim’s comparison of PC and the egg .
Click to expand...
This was an excellent and very useful thread.PC SUBS (Copy).jpg

'cept @CWLONGSHOT left us hanging on the Whelen results.;)

Maybe he followed up in another thread though.

I've messed with sub-sonic/"cat-sneeze" cast loads quite a bit and am back on that trail again, focused primarily on the 357 Mag in a carbine.

I'll try to find time to start a thread of my own on that, but this time a "can" is involved. I have some loads ready for it, but they are not specifically intended to expand yet - just be accurate and not make an extra hole in the can for now.

Form 4 was approved/4473 filed electronically, over a week ago. Now waiting for them to ship it to me.

My luck, it will show up the day school starts back up and I'll barely find time to test these loads, let alone post about it.:embarrassed:
 
Snakeoil

Snakeoil

Well-Known Member
Never heard of the egg experiment before. Interesting. I can see the value for hunting rounds. But don't see it for target shooting.

Friend bought some PC coated bullets a few years ago and they shot terribly. Granted, neither of us tried to make them shoot. They were so erratic that we simply laughed at the experience and went back to tried and true plain cast bullets.

Probably should make a better attempt at getting them to shoot. My guess is it will be a velocity sweet spot. But it could be a size thing, too. He gave me some and they sit in my cabinet. I guess I should at least measure them.
 
Spindrift

Spindrift

Well-Known Member
@Jeff H , those were some really nicely coated bullets! Looking forward to hearing more about your .357mag project!

@Snakeoil ; if you will, you could post some photos of the bullets, and some measurements. Someone might be able to give some advice regarding load data. Getting the best performance with coated bullets is a little different in some respects.
 
Snakeoil

Snakeoil

Well-Known Member
@Snakeoil ; if you will, you could post some photos of the bullets, and some measurements. Someone might be able to give some advice regarding load data. Getting the best performance with coated bullets is a little different in some respects.
Click to expand...

Okay. I have to remember to do it next time I go home. Will be at least a week before I head back.
 
fiver

fiver

Well-Known Member
Mike's 40-1 idea has worked since the 44-40 was invented.
it only failed when someone decided it was good enough for most of the sumthin dash sumthin cartridges so the newfangled magnums would probably do fine also.
 
Missionary

Missionary

Well-Known Member
I missed Glacier's egg / vinegar. That is a fine example of PC / 40-1. Thank you for dredging that up.
I guess PC has done for us chemically what paper patching has always been doing..
But no way do I want to have to start rolling thin / skinny cast with thin / wet paper just to pop a rock.
 
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