A 22-284 Build....The Baboon Slayer...Done Now With Pics

If you have the capability to dial in the bore using a 4 jaw chuck for chambering, why not hang it out far enough and thread it in that one set up... threads and chamber dialed to the bore....?

I prefer the thread fit slightly loose over slightly tight... 60 degree V threads self center on tightening...
 
todbartell said:
you'll run into dangerous pressures with 90gr over 3500 fps
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Have you any precedent for this statement..........it's more than a little open ended. Velocity has many variables making up it's final outcome in any cartridge and barrel combination. Pressure is but one of these variables, but one must also consider twist, barrel length, case capacity, bore size, volumetric efficiency, powder burn rates, length of leade, interior barrel finish, frictional coefficient of each bullet and more. I have to say TB, your statement, without any back up material, is quite meaningless.
I have already driven 80 gnrs at 3860 fps, without excess pressure in a 1-8 twist barrel, which would logically cause me to believe that attaining 3600 or so with a 90 grnr at reasonable pressures should be doable......as is with the 1-8 twist and a 27" barrel. Take that out to a 1-12 twist and a 30" barrel, it would seem logical to believe that 3800 fps would be within relatively easy reach, within the constraints of reasonable peak pressures.
 
Would a gain twist barrel help keep pressures down? I've read they do but have no first hand experience

The only pix I want to see it the terminal performance on said baboons!! A comparison of close range if possible to one from another zip code would be sweet
 
guntech said:
If you have the capability to dial in the bore using a 4 jaw chuck for chambering, why not hang it out far enough and thread it in that one set up... threads and chamber dialed to the bore....?

I prefer the thread fit slightly loose over slightly tight... 60 degree V threads self center on tightening...
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First question Dennis is due to the fact that the barrel is already contoured and I don't want to attempt to chuck up on the dished contour ahead of the shank, which then puts me too far down the barrel, where I can chuck on the straight taper, to work without a tailstock and center.

Second point, I think it's more terminology than differences in the work. When I say snug, I still mean being able to thread the barrel into the action all the way up to the shoulder (or recoil lug in this case), by hand. I know what you are saying though, I've had guys tell me that if one can thread a barrel in by hand then it is too loose, and I definitely disagree with this.
 
brybenn said:
Would a gain twist barrel help keep pressures down? I've read they do but have no first hand experience

The only pix I want to see it the terminal performance on said baboons!! A comparison of close range if possible to one from another zip code would be sweet
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Hey BB.........That will be interesting to see if there is a difference in the destructive force of this bullet and velocities. I personally, don't think we will see a lot of difference as I expect the bullet to completely explode on impact with pretty much anything out to a 1/2 Km or so, because as you know the rotation of the bullet decreases very little over the effective range of the bullet, thus at 250,000 RPM and being very close to the edge of bullet integrity break down, I think the effects at 1/2 Km will still be very graphic as well.

I have no experience with gain twist either but have discussed it at length with Bevan. It does seem to smooth out pressures a tad and thus allow for a little more powder and a little more velocity. Some say you give up a bit of accuracy and others say not. One thing I do know is that it never caught on with the benchrest boys........so who knows. Maybe that will be the next logical step in this program, a stainless 1 in 24-12 twist barrel. Maybe I can get 4200 fps...........
 
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Nice project, I had just finished playing around with a 1-8 twist 22-250. Wanted to try and get the berger 90 vld shooting fast. But They never could handle the twist. Not even at slow speeds.
 
uncledillers said:
Nice project, I had just finished playing around with a 1-8 twist 22-250. Wanted to try and get the berger 90 vld shooting fast. But They never could handle the twist. Not even at slow speeds.
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This is very interesting indeed. They suggest a 1:7 twist on their website, so you'd think the bullet would be fine at normal velocities. I can see where c-fbmi would cause headaches at the high velocity.
 
Yep 1899.......all that information is computer generated and theoretical. When you start driving them down barrels and chronographing and watching them vaporize or go sideways through the target, is really when you start to learn stuff..........For Berger to say that a 1-8 twist is required to stabilize their 90 grn @ 4000 fps, tells me they have never done it, they are just running the numbers through a computer program and printing what ever it spits out. If "uncledillers" can't get them to hang together in a 22-250, they wouldn't stand a snow balls chance in hell out of the 284 case..........Could be fun gernading gophers at about 30 mtrs though, just find that perfect distance just where the bullet loses it's integrity as it enters the gopher or even possibly an inch or so after it comes unglued. The video would not be recommended for minor audiences or those with delicate dispositions..........Does the term "Red Haze" mean anything to ya..........or "Kitty in a Blender"..........Oh no, wait, that one applies more to making mistakes while hunting elephants.
 
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Kingjenky said:
You guys obviously know what your talking about and I apologize for the derail but would it be possible to machine your own bullets out of whatever material then moly coat . Thanks
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Anyone....it's a legitimate question as your discussioning regular bullets not taking the stress....could steel bullets be machined and coated..
 
I have a 22-250 with a 7 twist. It shoots 90's at a tad over 3000 in a 22". I've used them to 1200 meters with zero stability problems. I've settled on the berger 80.5 though. It goes 3150 has a slightly lower bc but it's way less finicky to load for and cut groups into the .2s

Another great bullet is the 70 gmx...I've several groups in the .1s with this bullet.
 
Finally!

How do you know 90gr bullets won't stabilize in a 12 twist barrel?

The nosler 70gr. RDF with a bc of .416 most likely will at 4000fps.

Also... we need pics
 
Kingjenky said:
Anyone....it's a legitimate question as your discussioning regular bullets not taking the stress....could steel bullets be machined and coated..
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Kj..........The short answer is yes, of course. The long answer is a little more complex, there are already solid copper bullets that would take the stress, however I have found them to shed too much copper in the bore at such velocities and foul the rifling in as few as 16 rounds at 3500 fps. The issue with steel is that it isn't heavy enough and I suspect the coating one used may strip off in the bore.......think lead shot to steel shot and problems with the lighter steel shot. A lead cored bullet also "upsets" under the stress of ignition and acceleration which aids in sealing the bore as well as it is soft enough to allow the rifling to displace jacket material as it engraves with out any undue pressure spikes. This is the reason you see the grooves around the Barnes line of X bullets, it is to allow the displaced material from engraving to have a place to go without affecting peak pressure, however it is devastating to the actual BC of the bullet..........ever see an aircraft wing with corrugations opposing the airflow.......no, neither have I. Then there is the expense and time required to separately machine each bullet and then plate with whatever jacket material one decides upon.
The key to this discussion is to use a bullet and only spin it fast enough to be stable throughout it's flight and to get the balance of velocity to rotational stress exactly right. This bullet may not be the 80 gn Sierra, but I sure hope so as I have 500 of them.........Knowing that the 22-250 has stabilized this exact bullet at 230,000 RPM and knowing that it comes apart some where around 330,000 RPM, gives me a range within which to work with this bullet. The velocity is not what destroys the bullet it is the rotational stresses, the velocity and twist rate is what determines the actual rotation. If I cannot get the velocity to drive this bullet over the 230,000 RPM threshold with the 1-12 twist barrel then I may vey well have stability problems..........I do not forsee this being an issue unless this turns out to be one of those odd "slow" barrels, which can happen. I also know for sure that I cannot ever get enough velocity to drive this bullet over 300,000 RPM in the 1-12 barrel so I'm no longer worried about the bullets integrity. I believe I have that problem solved.........operative word there being "believe". However logic from the results of the experiment so far give me good reason to "believe" this.
So, in theory and based on the results of my own load work and that of 2 magazine articles (which I have no reason to disbelieve), if I can drive this bullet at 3800-4200 fps it will fall within the lower stable rotational range of this bullet, and it should easily maintain it's structural integrity............The key is to get all this theory and math worked out to be able to achieve the velocity one desires and then get them to consistently fall within 1/4 moa of the POA.

It might be interesting, just for the knowledge value of it, to work down the velocity scale just to see where in the rotational scheme of things, this bullet is unable to achieve stability.
 
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I personally think that manufacturers should publish the rotational requirements of their bullets, instead of saying 1-7 or 1-8 twist. I think their optimum stability in RPM or ### is what they should publish and then we could decide the best twist for our own cartridges and needs.
 
Doug, have you ever done a 6mm-7rem mag? I've been thinking of doing an overbore 6...the 6wsm to start, but with 7rem mag brass being so abundant....
 
No I have not, I have a great love for the 6mm-284, but have never put more case than that behind a 6mm bullet. I did most of my wildcatting prior to the glut of fantastic slow and consistent powders we have now. Now I'm just playing catch up with all the new powders and the existing cartridges that I own, that the new powders offer great improvements in.
 
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