6mm Creed Bullet blow up.

A

armednfree

New member
I just ordered a 6mm Creed Ruger American Predator. I intend to use 55 grain Nosler BT's and 65 grain V-max. I am concerned about bullet blow up.

Book velocities on the IMR 4064 I intend to use show 3900 fps on the 55grain and 3750 fps on the 65 grain. Those would be from an 8 twist barrel.

The rough formula on rotation, (MV*720/TR) shows 351,000 rpm on the 55 and
337,500 rpm on the 65.

Will those bullets likely take that or will I be trimming down the velocity?
 
The lighter bullets will have thinner jackets, you might have to trim the velocity down a bit. Try it and see what happens.
Note at those speeds if that bullet hits anything it will come apart.
 
I am counting on explosive expansion, just not until it gets there. I fired both bullets from a 243 I had, the 65's like a laser doing groups in the low 4's. But that was 10 twist.
 
I've run 40 gr. Nosler BT's out of 22 CHeetah, at over 4700 fps, w/o them coming apart. Prairie dogs sometimes simply disappear when that round hits them.
 
Isn't that a 14 to 16 inch twist? At 4700 fps that would be 338,400 RPM. The 1:8 at 3800 fps figures at 303,240 RPM. So, from what you say, theoretically the bullet should hold up.
 
Hornady made a bullet called S years ago in 22 cal. SX stood for super explosive. I don't know that they still make the bullet' At 3500fps they claimed it would blow up in flight, tried it and it did! These days' in one 243 I shoot 75gr V-Max bullet's. Don't blow up in flight, at least not yet but do blow up hitting a paper target attached to 1" foam board. That doesn't bother me a bit. For what i'd shoot it at, that good performance.
 
Speer 50 gr. TNT's were similarly rated at not over 3500 fps, but then in an Accurate reloading data book, they showed it at 3700 in a 22BR. HMmmmm. No factory 22 Br's, which would mean that they would all probably have better than factory grade barrels, or at least that's how I interpreted it. And I do run them out of my 22 BR at 3700, w/o problems. Very effective too.
 
The BT and VMax, in general, hold together quite well at high velocity.

I've pushed all of the light 6mm versions to between 3,800 and 3,900 fps without issue in 1:9" and 1:10" twists.

Yes, the 8 twist is faster, but I wouldn't worry about it.
 
Wow!
Someone worried about bullet blowup from the Manbun Lite.

All kidding aside, you should be fine.
Haven't heard much about bullet blowup from a 240 Weatherby, after all.
Or the 6mm-284, or the 6mm-350 Rem Mag, 6mm-06.

All have much greater powder volumes.
 
We are going to find out, but I think I probably am only going to load a few. Perhaps I should start at the 3300 load and just follow the data to the top 3750. Say 5 rounds of each. Speed test and data collection. All loads are going to be IMR 4064.

Now, would it bother me to have to slow it down? Not really. While I would like to shoot woodchucks with it I actually have both a 22-250 and a HB AR-15 for that. This is really a rifle I'm buying for when I retire in a few years. Then it's heavies at 1000 yards.
I figure with my Rem 700 STVF in 308, my custom 27" 284, this 6mm creed and then maybe a 6.5 creed I'll have enough toys to play with.
 
Armednfree,
I say go for the gusto! I fired some 357 diameter pistol bullets that are designed for less than 1500 fps in a 1:17 twist at 2700 fps in a 1:10 twist. I fully expected them to turn to powder before reaching 100 yards but they just printed a nice .30" group of five and a twenty round aggregate group of .33 inches. That was with all the 4064 powder I could cram in the case. The bullets were only seated to about 3/32" from the cannelure.

You only live once, take it to the limit!
 
In .224 Hornady VMax are rated for up to 4500 FPS without coming apart. Nostler BT 40 grain seem to hold up to full .220 Swift velocity with explosive results on varmints.
 
This is really a rifle I'm buying for when I retire in a few years. Then it's heavies at 1000 yards.
Click to expand...

If you blow varmint bullets out of it for a few years, you will need a new barrel to retire to Long Range with.
 
I'm not planning on shooting it a great deal like that, some though.

I figure this rifle is fairly new. Like a Savage it has a barrel nut so barrel swap will be easy. I figure to see barrels and wrenches come out for them fairly soon. Pac-Nor already does it in a prefit.
 
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"...The rough formula on rotation..." You're over complicating the whole thing.
Those 55 grain bullets with the MAX loads of IMR4064 are running 4036 FPS out of a 24" barrel. Your Predator has a 22" barrel. They'll be running less than 4,000 FPS anyway.
"...would like to shoot woodchucks..." They won't care what bullet, cartridge or how fast it was when it went through 'em.
 
Better Title would be CAN 6mm Bullets Blow up.

I say you should be starting low and working up anyway!

My book does not list 6 CM, but the large cartridges around it top out at 3800 max

You better get a barrel on order as well.
 
https://www.hornady.com/support/load-data/

https://sierrabulletsblog.com/2017/10/03/sierra-bullets-6mm6-5-creedmoor-load-data/

I'm going to see if a VMax blows up at high rotational speed. All with IMR 4064 and a 65 grain VMAX in a 1:7.7 twist 6mm creedmoor rifle.

37 grains @ 3300 fps and 308,571 RPM
40 grains @ 3500 fps and 327,272 RPM
43 grains at 3700 fps and 345,974 RPM

I've been told that the VMAX comes apart over 300,000 RPM and I note that the one Hornady factory loaded VMAX, the 87 grain, is loaded to 3210 fps which is 300,155 RPM. Yet they have data out taking that 87 grain to 3400 fps and the 65 grain to 3750 fps.

Since every 6mm Creedmoor I've ever heard of has a 1:8 or faster twist I can't see why they would develop loads that the bullet can't survive. I sent Hornady a question concerning this.
 
The Creedmore was designed with long range shooting in mind. At long range, high ballistic coefficient bullets are needed to minimize wind deflection. High ballistic coefficient bullets are long, so they need a fast spin to be stabilized. They are also heavy, so they aren't going as fast when they leave the muzzle as your light bullets will be, reducing the chance of core stripping, described below.

There is more than one potential consequence to over-spinning bullets. One is the in-flight disintegration you mentioned. Another is core stripping. This is where angular acceleration (rotational acceleration) at the pressure peak is so great the jacket of the bullet doesn't have a firm enough grip on the lead core of a bullet to pull the core around with it. This means the core slips inside the jacket. The jacket has internal impressions from the rifling that act as speed bumps for the core, so the core gets squeezed longer and looser inside the jacket. This greatly opens groups up.

Both core stripping and disintegration may be addressed by using solid bullets. They will be long for their weight and need to spin a bit faster than same-weight cup-and-core bullets do for stability anyway. Using bullets with heavy jackets and bonded core designs can reduce these problems.
 
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