224 Allen Magnum testing finished............

[Meister]

On my recent hunt to SD, I found myself glued to my Krieger straight barrel Rem 700. I was pushing 77 grainers at about 2800 thru the 1-7 4 groove, they were deadly accurate out past 800, and I did get lucky and drop one at 1040. They were still grouping well at that range, I dunno why, they should have been going sub well before that. The ability to watch the bullet in flight was amazing, and helpful.

Another hunter was using his 22-250 out to 450-500 with success, but had to go to his 308 after that. He and I have been talking about rebarreling his factory rem 700 to a fast twist for the long stuff. Our biggest concern is carbon buildup (leading to shorter barrel life)with the heavier bullets as well as reduced case capacity unless the throat is cut long. Am I being overly cautious? /ubbthreads/images/graemlins/confused.gif

 

[Fiftydriver]

Brian,

I tested the 100 gr and 107 gr ULD RBBTs in a customers 30" 22-6mm AI and got velocities up to 3250 fps but with the 1-8 twist I never got one to hit paper except when I moved up to 30 yards and then I got a couple full profile holes.

I was getting pretty consistant accuracy at 100 yards with anything up to 3100 fps, over that and things shut off instantly, almost to the FPS which I have found is common with this type of bullet when it is spun to fast. They just let go at a certain point.

I did not test at any range other then 100 yards except when I was fire forming some cases which were in a load that produced just shy of 3000 fps. These were reliable out to 500 yards just plinking but when I tried to stretch them past that I never saw a bullet impact.

Now please keep in mind several things. The 22-6mm AI I tested the 100 and 107 gr pills with was a 1-8 3 groove Lilja. My 1-7 twist barrel on my 224 AM is also a 3 groove. It has been proven time and again that 3 groove barrels are hell on thin jacketed bullets that are heavy for their caliber driven to high velocity in a fast twist barrel.

I have no idea what a 4 groove barrel will do. I will say that I suspect the Krieger will be a true 6.5 twist barrel. Cut rifles barrels are generally spot on their advertised twist rate. A button rifled barre on the other hand will often be slightly slower then its advertised twist range.

When I get to testing another version of the 224 AM, it will be with a 1-7 twist barrel still but this will be a 5 or 6 groove barrel instead of a 3 groove.

I have no idea what you should expect from your testing but I would certainly see what happens. Even if you can get 3100 fps it will still be usible in your Clark. Certainly not what your looking for but usible. You may well play with 3200 fps in the 4 groove, just have to throw some bullets and find out.

In earlier tests with my 224 AM, I actually hit 3450 fps with the 107 gr ULD RBBT and AA8700 powder in the 26" barrel. Still, no bullets landed on paper.

In this last test, accuracy went from sub 1/2 moa up to 3100 fps to no bullets on paper over that velocity. I even had two spotters watching for bullet strikes around the target and none were seen, I am suspecting they were just spun apart.

The 107s acted nearly identical to the 100 gr pills dispite the heavier jacket. This is something that has baffled Richard and myself???

Again, I want to stress that I was only using 3 groove barrels. Do not give up testing the Wildcat 100 and 107 gr bullets because of my test results because your tests may well prove totally different!! Only way to know is to get bullets in the air.

As far as the 142 gr ULD RBBTs are concerned. I have tested them in my 257 AM as well in a couple 257 STWs in 30" barrels.

In the STW, a 1-10 will not cut it. A 1-8 will and my test barrel shot them pretty darn well even with an over sized bore(bad barrel).

In my 257 Allen Mag with the 1-7 3 groove, 3250 fps was producing fine accuracy but this round will drive a 156 gr ULD RBBT to this velocity easily. Anything above this with the 142 gr ULD RBBT was what appeared to be dusting the bullets.

For a 142 gr ULD RBBT I would recommend a 1-8 5 or 6 groove again. In your 257 Wby, I suspect you will be pushing the bullet with a 1-7 twist but I think you will probably be fine. That 3200-3250 fps range is usually the let off velocity with a J-4 jacket, I think you will be in good shape, you should be set up perfectly for the 156 gr ULD RBBTs if you need to use them. You should be able to break 3000 fps with this bullet and from my drop test numbers you will get around a BC of .800 which when combined with 3000 fps is pretty **** impressive!!!

Keep us posted as to your results!!

Kirby Allen(50)

 

[Fiftydriver]

Meister,

I would not be overly worried about carbon build up. If you use a chambering in the 22 BR, 22 Dasher, 22-250, 22-250 AI and similiar rounds, you will be loading to upper end pressures with very clean burning powders. Carbon build up should not be a huge concern.

For example, a 22-250 AI with a 100 gr ULD RBBT should easily be able to push 3000 fps with good clean working pressures. if you think your 77 gr pills at 2800 fps were impressive you will be really impressed with the 100 gr ULD RBBTs at 200 fps more velocity.

Good Shooting!!

Kirby Allen(50)

 

[brianwinzor]

Kirby, Great information which will be very helpful.

I certainly will still proceed with testing both the 100 and 107's in the 224 Clark, and if I can get around the 3,100 "ceiling" with the 107 at sub 0.5 moa, then I will be happy as a pig in you no what. I was only expecting to get about 3,150 with that bullet any way.

In retrospect I wish that when ordering the .224 Krieger, that I had chosen a 7 twist instead of 6.5 twist. However, at the time I believed that the 7 twist would stabilise the 100 grain bullet, but may struggle with the extra .050 length of the 107, so I decided to be conservative and went with the 6.5.

I will certainly try the 142 ULD's in the 257 Weatherby, but if they do dust at around 3,200 - 3250 fps, then I will stick with the 156, as I have good supply of them and your testing has shown that they perform well up until about 3350 fps. I agree with your prediction that the 257 Weatherby should get around 3000 fps with the 156 ULD.

I was originally hoping to use the 7mm Dakota case for this project, but my gunsmith has a 257 Weatherby reamer, and was ready to go, and there was going to be a 2 -3 month delay in getting a reamer for the 25/7mm Dakota. The clincher was the $A300 cost of getting 100 7mm Dakota cases to Oz, compared to $A85 for 100 7mm RUM cases that I recently purchased here.

So if the performance of the 257Weatherby is not up to expectations, I will neck down and shorten the 7mm RUM cases to about 2.550 inches, have Bill (my gunsmith) set back the barrel and start again.

I will certainly keep you posted with my results, and have a happy long week end with the Graves. Regards, Brian.

 

[Fiftydriver]

Brian,

What chambering are you using to get the 156 gr ULD RBBT up to 3350 fps?

Just curious what your using.

Kirby Allen(50)

 

[brianwinzor]

Kirby, Perhaps I should have re worded my post, but I am not expecting to achieve 3350 fps with the 257 Weatherby or later on in the shortened 7mm RUM. I meant to convey that my decision to switch to the 156 grain ULD from the 142 ULD was based on your experience with the bullet, and that you were able to use it successfully in your 257 AM at velocities up to about 3,350 fps.

I did some preliminary case capacity experiments and found that the new Norma 257 Weatherby brass (2.545 inches) held 87.8 grains of H870.

The new 7mm RUM cases (2.845 inches)held 114.5 grains of H870, and about 109.0 grains to the base of the neck. I estimated by filling the case to different levels, that to get about 90.0 grains of H870 occupying to the base of the neck, I would have to shorten the case to about 2.475 inches, assuming that I maintained the same shoulder angle and neck length.

At this stage I intend to chronograph and accuracy test the 125, 142, and 156 grain bullets in the 257 Weatherby, and use it in the field for about 12 months, then make an assessment of what the end capacity of my shortened 25/7mm RUM should be.

The complicating factor in making that assessment is that Norma brass has a reputation for being soft in the head, and that the 7mm RUM brass of equal capacity may show less pressure.

The other factor for consideration is available powders here in Oz that are likely to enable me to achieve 95 - 100% loading density at maximum pressure with the 156 grain bullet. I currently have a supply of H870, but the only local powder is AR 2218 (H50BMG in US). However, earlier this week I spoke to the Vihtavouri distributor, and if I order at least 3kg (6.6lbs) I could get some 20N29 included in his next shipment, which would be about 12 months away.

I would like the 25/7mm RUM short to be able to achieve at least 3,150 fps in the 26 inch Krieger barrel, if the 257 Weatherby can achieve 3,000 fps. It will be interesting to see if that can be achieved. Regards, Brian.

 

[Fiftydriver]

Brian,

I see what you are saying.

If I may offer some food for thought about your new wildcat design. First off I think its a hell of an idea, basically the exact same thing as my 257 Allen Xpress based on the 300 Dakota case which is 2.550" long. Everything else is the same with the Xpress as it is with the Allen Mag, just a shorter case body.

I will be building a light weight rifle in 257 Allen Xpress here soon for a hunting rifle and will be testing the 142 and 156 gr ULD RBBTs in this rifle. I have already tested the 6.5mm Allen Xpress which is the same thing as the 257 Xpress just necked up to 6.5mm. In a 26" barrel it will easily drive a 142 class bullet to 3300 fps so I suspect you will definately get to the 3150 fps level.

As to my advice, because you are limited with the powders you can use, you may want to consider using a shoulder angle in the 25 to 28 degree range. 25 degrees is the same as the STW rounds. The reason I say this is because if you go to a steeper shoulder or even retain the 30 degree angle of the RUM case, you more then likely will run into powder bridging issues with any slow burning stick powder.

I can not use any stick powders in my 257 Allen Mag for this reason. I can only use Ramshot Magnum, AA8700, H-870, US869 or WC872.

H-50BMG is a very large kernal powder as is 20N29. I suspect you may have problems with these powders and powder bridging, the best change you would have to avoid this is a shallower shoulder angle.

I know, not sexy or modern looking really but it may be vastly more functional. I still do not think H-50BMG and 20N29 would work but you could use powders such as Retumbo, RL-25 or similiar burn rate powders as these both perform very well in the STW.

Can you get the new US869 powder from Hodgdon? this would be a great one with the heavy bullets.

Anyway, just a thought on the shoulder angle, I personally feel anything 30 degrees and steeper is to much for stick powders in a 25 cal bore with this diameter of a case.

Just my opinion,

Kirby Allen(50)

 

[scott]

Just a thought, why not use the same 7mmRum case with the 257 and 6.5mm AM as you do with the 277 AM, and keep the shoulder angle on par with say a 06 case, would not this help powder bridging, and keep the case capacity down somewhat. and be able to use either ball or stick powders.

I would not give up on the 224 AM, I think you have something... we can not all have a success on the first try..
I'd go with a 8 twist 6 grove 30 inch bbl, I think the 8 twist would be better over 3000 fps in the WSM case.. as long as you keep the vel high.

I'd like to see a 243 AM (6mm AM) also..

hope you don't give up, you are a godsend to us LR hunters.

scotty

 

[brianwinzor]

Kirby, Thanks for the input, as always very helpful.

I have never experienced the phenomenon of the extruded powders bridging and causing pressure spikes, but I will heed your advice when designing the shortened 7mm RUM case and keep the shoulder angle to a maximum of 28 degrees, if it will help in giving me maximum flexibility in choice of powders.

I made the decision some months ago that when building future rifles, to only use shoulder angles of 30 degrees or less on my cases to improve the feeding through the magazine. Currently am also using a 22/250AI (28) which some call a 22/250 RCBS, and the .224 Clark has a 30 degree shoulder. My .17/222 mag imp (40) produces good ballistics, but feeds poorly, and now that Richard has got those 45 grain .956 inch missiles ready to test, I am thinking about either redesigning that case with slightly more body taper and using a 28 degree shoulder, or using a different case of similar capacity. Strangely the 25/06AI (40) feeds perfectly in my Custom Sako L61R action, but feeds like a dog in the Sako AV action.

I will certainly be following with interest your results with the 257 Allen Express as it should have a similar case capacity to the shortened 25/7mm RUM that I am proposing.

I am hoping that Hodgon US869 will become available here in Oz, as is appears to be a little slower than my H870. Winchester powders have always been available in Oz, and now that Hodgdon are the distributors of Winchester powders, perhaps they will include some US869 in their shipment of the other Winchester powders to Oz.

I certainly will use my supplies of Re25, Viht N170, and AR2225 (HRetumbo) when testing the 142 and 156 grain bullets in the 257 Weatherby and 25/7mm RUM short.

However, my results with those powders with the 142 and 156 grain bullets in the 25/06AI showed that Reloader 25 was about 7 grains faster burning than H870, and AR2225, and VihtN170 were about 4- 5 grains faster burning than H870. Consequently, when using Re25, VihtN170, and AR2225 with the 142 & 156 in the much larger 257 Weatherby & 25/7mm RUM short, I believe that I would struggle to get 90% loading density, let alone my consistent aim of 95 - 100%.

I would love to be able to get you to build me a 257 Allen Express, but at the moment, all the bureaucratic costs in gaining US State Dept approval, courier, and Oz Customs costs would make it prohibitive at the moment.

Yesterday, I had a great chat with Richard, and as a result am feeling bouyant after hearing what he is doing to overcome existing bullet jacket problems, and what he is proposing to build in the future.WOW!!!!!!!! He certainly is a great "bloke" and a gem for the wildcatter, and I will continue to buy his bullets.

Look forward to hearing your reports. Regards, Brian.

 

[Fiftydriver]

Scott,

Just to clean up any confusion, the 277 Allen Mag is based on the 338 Lapua parent case, the 270 Allen Mag is based on the 7mm RUM.

I could have easily used the standar 7mm RUM case for the 257 and 6.5mm AMs but the design of these rounds was to allow them to fit in standard length receivers when throated very short with bullets in the 130 gr class weight to work in receivers such as Win M70s with standard length receivers.

That works very well, offering full length RUM capacity, in fact a bit more in a significantly shorter OAL round. When I designed the Allen Xpress rounds this sort of eliminated the need to short throat the AMs.

The reason I do not care for a shallow shoulder angle is becasue of brass stretching. These cases have alot of shoulder area, even with a shallow shoulder angle. Rem brass is not overly hard in the case head and brass flowing under high pressure can be a problem with a shallow shoulder angle. This was the main design reason for the shoulder angle I used.

Now that we have alot of slow burning ball powders this is not really a handicap. Beside, with a 25 cal with the capacity of the 257 AM, the slow ball powders are really the only good options to get high load density anyway so it works out well. Long case life, high performance.

I am not giving up on the 224 AM yet. Will have some reports on new testing soon.

Good Shooting!!

Kirby Allen(50)

 

[Fiftydriver]

Brian,

I would fully agree with your theory on shoulder angle with round of 6.5mm bore diameter and under.

I will also agree that Richard has and will do more for wildcatters then any bullet maker I know. We played with some prototype 195 gr ULD RBBTs in his 277 AM this last weekend, all I can say is ****!!!

Good Shooting!!

Kirby Allen(50)

 

[bailey1474]

[ QUOTE ]
We played with some prototype 195 gr ULD RBBTs in his 277 AM this last weekend, all I can say is ****!!!

[/ QUOTE ]

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[Fiftydriver]

/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

ME TOO!!! Now I got to build myself a 270 AM or 277 AM to use them. Sold my last one.....

Kirby Allen(50)

 

[jett]

Kirby,
How fast will a 270 AM push the 195?
Do you have a guess about the BC?
Is Richard still considering the 185?
Thanks,
Jett