7mm Allen Mag test rifle finished.....

kac1345

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ss7mm I know ...I just can't decide on what one to get...I started out wanting Kirby to build me a .257STW...this was right before the AM's started...I have to say Kiby is one helluva great guy...I asked him if he had a case for the 257 STW..He did not ask for any postage or anyting...he sent me one with a 100 grain Ballistic tip seated for referance...now that is a cool guy! in my book...even though it was small he took the time to pack it up and ship it off to me. Anyways back to the AM's I had the hots for the . 257 AM but it seems like every new one he makes they just get better and better...the 270 and the 7mm have my attention now. /ubbthreads/images/graemlins/grin.gif
decisions decisions lol
 

ss7mm

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LRDT:

I guess it just depends on what you want to do and how far away you want to be able to do it reliably and with the precision necessary at the very extended ranges.

If you run the numbers in something like Exbal on the 270 AM and the 169.5 Wildcat ULD, it will amaze you.

Then, run the numbers on the 7mm AM with the 200 grain Wildcat ULD, and you will find that it does it easier, farther, faster, with more power, and possibly most important under field conditions, does it with far less wind drift.

You can load the 7mm AM with 140 grain laser pills and quite possibly do it at about 3900f.p.s. for the “red mist” effect. You can then switch to the 200 grain Wildcats and really reach out and touch something, especially if it’s the size of a deer, elk etc.

I chose the 7mm because it’s going to be my main hunting rifle. As an added bonus I can also load the little lasers when the 200’s aren’t needed, but I’ve got a feeling the 200’s will be it’s main diet.

It’ll also be nice because we will also have the 270 A.M in addition to the 7mm A.M. to play with.
 

kac1345

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Yeah the heavy pills with the High BC's are apealing to me. Just curious what action are you going with? I had a Rem 700 that I was going to send Kirby for the STW build ...but seen the AM coming and decided to wait...since then it has been turned into a 300WM so I need another Doner.
 

Fiftydriver

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I have read though the posts since my last posting and am happy to see this has turned to a friendly debate compared to some of the flaming matches that generally pop up on the other boards.

This is what makes LRH the great place it is.

First off we all know what these rounds are, extreme performance, big case capacity, small bore rounds. Yes that equates to abrevated barrel life to some degree but every step has been taken to increase barrel life and for the uses these wildcats were designed for, I feel it is a very acceptible barrel life.

No offense taken in any way and I hope none received from my posts /ubbthreads/images/graemlins/grin.gif!!

Kirby Allen(50)
 

Eaglet

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Fiftydriver,
[ QUOTE ]
This is what makes LRH the great place it is.

[/ QUOTE ]
I'll drink to that! (Coffee!) /ubbthreads/images/graemlins/smile.gif
 

Fiftydriver

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Dave,

Velocity potential is an interesting topic with the Allen Mags. I will go through each one and respond to the powder issue.

With the 257 and 6.5mm Allen Mag, you simply do not have an option to use the stick powders. This is a safety issue here. In fact the rifles I ship in these calibers are clearly marked on the barrel that they have to use only Ball powder.

This is because the case capacity is so large and they are so wide in the shoulder for their bore size that a powder bridging problem occurs with stick powders. Even powders of the correct burn rate.

For light weight bullets in the 100-120 gr range, Magnum from Ram shot is showing promise but for all around use, AA8700 is working best for bullets from 100-130 gr. For bullets from 130 to the top of the scale(156 in 157 and 169.5 in 6.5mm) WC872 is the best powder I have found to use.

In these two Allen Mags you simply don;t have an option. As far as velocity. The 257 Allen Mag will drive a 100 gr Bonded Core FBHP to 4090 fps in a 29 3/4" barrel with 107.0 gr AA8700. In the same exact barrel as a 257 STW at a full 30", it would top out at 3950 fps with Retumbo so youcan take what you will from that comparision. Again these numbers are out of the same barrel, originally a 257 STW, and then slightly shortened and rechambered to my 257 Allen Mag.

270 Allen Mag.

This round has a bore diameter large enough to allow use of teh stick powders. In fact with the 130 to 140 gr bullet weights you will get higher performance with powders such as Retumbo and Rl-25 but again at the expense of higher bore heat and top velocity will only be 50-75 fps faster then with the ball powders. Again, I would much rather get longer barrel life and cut 50 fps off the load. This amount of velocity is totally meaningless at extended range, well, any range for that matter.

For the heavy bullets such as the 169.5 gr ULD, I honestly have not tried any stick powders. I started with WC872 at 90.0 gr and worked up to 105.0 gr until the primer pockets loosened up and then dropped back down to 102.0 gr for a max working load.

Top velocities averaged 3394 fps with extreme spreads for ten shots in the high teens, low 20's which is fine with me.

The load I actually use is 100.0 gr WC872 which produces right at 3275 fps. Nothing flashy but a .750 BC bullet at nearly 3300 fps is a thing to behold when she lands at 1000 yards. I am still amazed at the quickness that bullets get on target at this range. You better be ready or you will miss the hit.

Compared to the 338 Kahn driving a 300 gr ULD to 3050 fps, it makes the Kahn seem like a lazy dog as far as time of flight is concerned. Again this is about 20% because of the round design and 80% of the Wildcat Bullets.

I want to stress this to everyone. The Allen Magnums are great high performance rounds in and of themselves but it is only when combined with the amazing Wildcat ULD RBBT or ULD Bonded Core FBHP bullets that you see the extreme performance potential of these rounds.

Without the hard work and genious of Richard Graves who has offered as much to these projects as myself, the results would not be nearly as impressive as they are. He has been an equal partner in every Allen Mag so far and the ones in the works and I just hope he knows how greatly I respect his knowledge in bullets and ballistics and above all else how much I honor his friendship. Without Richard Graves there are no Allen Magnum rounds.

So back to the question of velocity and powder choice. I don't know with the 270 AM and the heavier bullets. I have not had a reason to think the grass may be greener somewhere else. This is my point with the Allen Mags, you find a load that is a good consistant load and then use the system in the field and you will see the rewards first hand.

I will say I am not going to try the stick powders in my rifles but I will develope loads in customers rifles for the componants they want to use before I ship the rifle.

7mm Allen Mag

Obviously this round will work well with a variaty of stick powders, for light bullets, H-1000, IMR 7828, RL-25, Retumbo. For middle weight bullets, Retumbo, RL-25, H-50BMG. But I suspect for the heavies, 175 to 200 gr ULDs, WC872 will again be a top performer and again with the increase barrel life, I will take even 100 fps drop in velocity. These rounds have plenty of horsepower as is, even if you are 100 fps off the top velocity potential, again this is because of the Wildcat ULDs.

So yes, in some cases, top velocity may be with stick powders but I hold barrel life to a higher premium then getting the last fps of velocity out of my rounds.

Flame cutting is more controled by throat to bullet fit then by the rifling design in my opinion. The way I look at it, I want the bullet to seal the gas behind it in the throat area so that it does not blast around the bullet and flame cut the throat and origins of the rifling. This is my theory, take it for what you will.

In my rifles, when you chamber a round loaded with a Wildcat bullet, often you will see contact rubs on the bullet body from the throat. This is how tight the throats are. While this does increase pressure slightly it is of no concern since the loads are developed for this throat design from the ground up. Kind of like seating bullets into the lands. If you develope the load from the start with this seating method, there are no pressure problems, same thing here.

As such they are very tight fits to the bullets which is by design to limit flame cutting as much as possible. This is the killer of the throat, limit this as much as possible and the battle to good usible barrel life is much easier to contend with. Again, this is my theory and so far it seems to be holding true.

I actually started doing throats like this by accident. When I designed my 338 Kahn, I had the reamer come with a .3385" throat diameter. Well, I quickly realized that most 300 gr bullets, Sierra or Wildcat, have a bullet diameter of roughly this same diameter. I have shot the rifle and while I can probably not reach the peak velocity I could with a slightly looser bore, I have about 500 rounds down the pipe and the throat is still in VERY good shape, even using H-50BMG for most of my shooting which I have now switched for WC872.

So this is the system I started using and so far it has been producing longer barrel life then the standard 0.0005" over bullet diameter system.

Good Shooting!!

Kirby Allen(50)
 

Fiftydriver

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LRDT,

I have enjoyed our correspondences and appreciate your knowledge and experience. I will also tell you that if you want a 257 magnum for 100 gr bullet weights, the STW is more practical then the Allen Mag which really likes bullets of 130 and heavier.

As far as receivers to use, for all the Allen Mags up to the 270 Allen Mag, the Rem 700 is hard to beat.

For the 7mm Allen Mag, We will see how the Rem 700 performs the testing I will perform on it but I suspect it will do extremely well.

ss7mm selected a rifle built with the best available componants in the world. It will be a truely impressive rifle when finished and I suspect he will post many pics of the rifle as well as some tiny little groups at very long ranges.

Good Shooting!!

Kirby Allen(50)
 

Fiftydriver

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7mmag man,

The 257 and 6.5mm Allen Mags have the felt recoil of a 7mm Rem Mag to 300 Win Mag depending on which bullet weights you use.

The 270 Allen Mag feels exactly like a 7mm RUM or heavy loaded 300 Win Mag loading.

The 7mm Allen Mag will be in the class of the 300 RUM or very close to it. It all depends on the rifle weight you choose.

The 338 Allen mag will kick the HELL OUT OF YOU!!! /ubbthreads/images/graemlins/grin.gif

But with a powder charge of 150 gr under a 300 gr ULD or 140 gr under a 350 gr ULD bullet, what could one expect!!!!! My test rifle will be around 55 lbs and yes I am going to still machine a brake for it. I am looking for 22 long rifle recoil with 8500 ft/lbs of energy!!

We will see /ubbthreads/images/graemlins/grin.gif!

Good Shooting!!

Kirby Allen(50)
 

davewilson

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i would like to thank you for all the in depth info. good stuff. but i would like to clarify that throat dimension.are you saying you basically have "no clearance" in the throat.a 7mm would be .2840 ?
 

Fiftydriver

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Dave,

There is clearance but 0.0002 is what I like to hold as max and min if possible if that makes any sense at all /ubbthreads/images/graemlins/confused.gif!

Kirby Allen(50)
 

alremkin

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My $0.02 on barrel burn out stuff...I have enough other rifles to not have to shoot an over bore magnum for practice. So other than load developement, which I believe you have said you will advise and assist your customers with this, I would imagine firing about 10 rounds/year out of such a rifle. Then, to fire 1,000 rounds would be 10 rounds x 100 years =1,000 rounds fired. A hunting lifetime and then some...

The smaller caliber Allen Magnums should work for just about eveything in the lower 48 states. Being in Canada and mainly interested in huntig Elk and Moose in Grizzly country I much prefer the big 338's. Many years ago I fantasied about 338/505. I've heard that basically that's what the 408 Cheytac is, a redesigned, strengthened, necked down, 505 case. Please don't tease us about a new ultra 338. Tell us a bit more about it. Is it based on the Cheytac case? Or is it a somewhat toned down 338 Talbot? What have you got up your sleeve now? Also will you be able to make it into something someone could hunt with, ie carry, in say a 30" barrel and how much would it weigh without sacrificing too much accuracy? /ubbthreads/images/graemlins/confused.gif I understand you won't know all of this now, but I'd like to hear what your thinking is on it now. /ubbthreads/images/graemlins/cool.gif
 
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