Lightweight 7mm Allen Magnum pics....

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Fiftydriver, Aug 13, 2006.

  1. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Well, I got her assembled this morning but it is not ready to shoot yet. I have another two days to wait for the bedding to fully cure. No sense pushing things and have the bedding set back anywhere.

    I designed this rifle as my Extreme Sporter model from APS. For a full size rifle, very light weight, alot of power and alot or reach. Here are a list of the componants I used in this rifle:

    -Rem 700, Chrome Moly receiver, Fully accurized
    -Sako extractor
    -Gre Tan Striker assembly
    -Factory trigger tuned to 1.75 lbs
    -Holland Comp Recoil Lug
    -Lilja SS #3 contour, 27" 7mm barrel 1-9" twist 6 groove
    -Defensive Edge 1/2" thread triple port brake
    -H-S Precision Sporter stock Forest Green with Black web
    -H-S Precision DM system
    -APS Skim bedding
    -Defensive Edge flat black teflon coating
    -Burris double dovetail two piece bases
    -Burris low 30mm Signature rings
    -Leupold Mk4 3.5-10x 40mm TMR FFP
    -Harris BR bipod

    As she sits in the pic I would guess it to weigh right at 8.5 lbs, maybe a hair more with the bipod. I could have really dropped the weight down more had I gone with a lighter scope then the Leuy Mk4 but it is plenty light enough to allow for the scope upgrade.

    This is the new Front Focal plane Mk4 from Leupold. Finally they decided to come out with a FFP scope and I think this may be one of the best LR big game scopes out there. Only thing I think that would rivel is would be the same model in a 4.5-14x version.

    With the 40mm objective you can keep the scope down close to the receiver. This rifle feels amazing to shoulder and the scope positioning is RIGHT there. I am already in love with this rifle and have not even shot it yet!!

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    This rifle has a barrel much lighter then what are common on my LR hunting rifle and that is because this will be my "go to" general purpose big game rifle. I designed it to be able to reach out 800 yards on big game but also to be able to be packed around all day in hard country all day.

    I also wanted it to be usible in close cover as well as open country. This is the reason for the shorter then usual for me 27" barrel and lower powered scope at 3.5-10x. Personally, I feel this is plenty of power for taking high quality shots at deer size game and larger out to 1K yards easily. Some prefer much higher powered scopes but I have never been left wanting more then 10x even out to 1000 yards on deer size game. As I will be limiting my shooting to this range and probably much less with this rifle, the 3.5-10 is about as perfect as it gets for my needs and the FFP reticle makes it even more useful allowing me to use my reticle on any power as a reference point drop system.

    I plan on using the 200 gr ULD RBBT in this rifle. In my 30" barreled rifles I loaded this bullet to 3200 fps comfortably. The 7mm AM has more to offer with a 30" barrel length but to ease things for the J-4 jacketed bullet I feel 3200 fps should be the limit.

    As that is a comfortable load in the 30" barrels, I suspect I may well be able to reach the same velocity potential in the shorter 27" pipe running full pressures for the case design.

    I will be very happy with 3100 to 3150 fps if that is what the result is. That velocity with the BC of this bullet will still stand alone ballistically in any 7mm crowd and pretty well most any caliber out there.

    My only question is the 1-9 twist. This is an experiment to be honest to see what the slower twist and 6 groove rifling design will do with the J-4 jacketed bullets.

    In some prelim testing with a Rock 1-8 5R barrel, this bullet was able to be driven to 3350 fps with fine accuracy. I am predicting the 6 groove Lilja will perform nearly the same and allow a bit more velocity potential with less stress to the bullet.

    We will see.

    Final goals, a 200 gr ULD RBBT at 3100-3200 fps in a 8.5 lb class rifle with 1000 yard reach. We will have to see what happens when the bullets fly.

    If the 1-9 proves to be not enough to stablize the 200 gr ULD RBBT at long range, I have some 175 gr and 169.5 gr ULD RBBT 7mm bullets waiting in the wings to jump into the fight. I have no doubt about this twist with these two bullet weights.

    Because of the relatively light barrel, I am not expecting or demanding 1/4 moa groups from this rifle. In all honesty, if I can get the ULD RBBT bullets to print in the 1/2 to 3/4 moa average range for three shots with this rifle I will be happy as can be. If I can get this level of consistancy at 100 yards, I am not worried what will happen at long range. Tend to get lower in moa measurement from 100 yards out anyway.

    Hope to get the barrel broke in by end of next week and some range reports by next weekend. Back to work for now though /ubbthreads/images/graemlins/grin.gif!!!

    Kirby Allen(50)
     
  2. remingtonman_25_06

    remingtonman_25_06 Well-Known Member

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    Good looking rifle Kirby. The chrome moly receiver is essentially a blued receiver, right? I suspect that rifle will still have great accuracy, and of course, some downrange punch to go with it. Cant wait to see how it shoots.
     

  3. Buffalobob

    Buffalobob Writers Guild

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    Very nice looking stock.
    You should have added a splash of orange though. /ubbthreads/images/graemlins/grin.gif

    Be interesting to see what powder gives the best results in the shorter barrel.
     
  4. ss7mm

    ss7mm Writers Guild

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    Kirby:

    What can I saw but....SWEET /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/shocked.gif /ubbthreads/images/graemlins/grin.gif

    Can you spell Ultimate Long Range Big Game Packing Rifle??? /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif Talk about a portable long range thumper, I think you hit it right on the nose. I like the color combo. As usual, it looks like Shawn did another fine job on the coating. Looks fitting on a true big game hunting rifle. Kinda like a wolf in sheeps clothing. Looks can be deceiving and if viewed quickly or from a distance, first impressions would be deceiving as to what this one is fully capable of doing.

    That thing just looks like a premier packing type hunting rifle without even firing a shot. Can't wait to hear how the testing goes. Keep us posted. Should be some interesting reading. Kind of strange seeing an Allen Magnum in a shorter barrel but I know it'll work. The round and the bullets will get the job done at any range you plan on using this thing at, and even longer if needed.

    Whitetails in the brush to mulies and speed goats at 1000 yards plus. What more could you ask for?? /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/grin.gif
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    RemMan,

    I only use chrome moly(blued) receivers when I build a 7mm AM on a Rem 700. Steel is more resistant to bolt lug set back then stainless.

    I am sure she will be a shooter with some combination of load!!

    Kirby Allen(50)
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Buffalobob,

    Where ever did you get the idea to put orange in this color pattern /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif!!!

    Kirby Allen(50)
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    SS7mm,

    I hate to say it but this little pill maybe my primary hunting rifle but this fall in Idaho with Shawn she will be playing second role, hopefully!! That is if I get a BAT receiver in here soon!!

    When I thought up how I wanted to build the rifle I wanted a one rifle for everything type design. From pronghorns to moose, from 100 to 800 yards and from sitting in stands to walking for miles I wanted a one rifle for everything type deal.

    I think this one will come close, if it shoots!!

    Kirby Allen(50)

    PS. I sent you a couple e-mails, did you get them? did not get any response from you on them??? Keep me posted.
     
  8. TMR

    TMR Well-Known Member

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    Definitely the ulimate packing rifle.....another fine job Kirby.

    Looks like I might have to have another one built, and I still have a few months to wait on the one you are building now. Maybe a guy should have a lightweight and a med-hvy weight? Looking foward to seeing the test data...
     
  9. wildcat

    wildcat Well-Known Member

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    Fifty, the rifle looks great. Let us know how she KICKS. Is that your brake on the rifle.
     
  10. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Wildcat,

    No that brake is one of Shawn Carlocks. I really like the look of this brake. Very small in diameter but has alot of surface area in the partitions because of the round port designs. I also believe the round ports will give the brake a more "directional" effect on the recoil meaning it will act more directly against the recoil because it will be concentarated in a more definate vector against the line of recoil.

    I think it will work very well. The lighter the rifle, the larger the case capacity and the smaller the bore, the better the brakes work. I would not be suprised to have the sensation that the rifle is being pulled away from me when I fire it.

    Wishful thinking maybe but in a rifle this light it is not uncommon to feel this.

    Kirby Allen(50)
     
  11. lerch

    lerch <strong>SPONSOR</strong>

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    Good looking rig Kirby

    I am ready to hear what you think about the bbl when you get her going. Just a nice, clean looking setup that is ready to do some damage.

    take it easy
    steve
     
  12. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    You've got to stop turning out rifles and posting these pics!! Makes me want to build something else!!! Good looking rig. Will be curious to see how she shoots w/the heavey bullets and that pencil bbl.
     
  13. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Got out early this morning for the first range test of my lightweight 7mm AM looking for velocity testing and stability testing.

    This is the first time I have personally used a 1-9 twist 6 groove Lilja barrel with my 7mm AM and the 200 gr ULD RBBT. Combine that with the very light #3 contour 27" barrel and I was very curious what to expect.

    First test went pretty good. Conditions were 65 degrees with 90% humidity!!! It was sticky out there this morning, alot of rain yesterday.

    My load consistated of formed Norma cases(had 100 new cases to use up. Very good quality but MUCH softer then Lapua hulls), Hodgdons new US869 powder, Fed 215 primers and the Wildcat 200 gr ULD RBBT seated to an over all length of 3.625".

    Just for reference, in this rifle, an OAL of 3.660" will just touch the lands. We are finding that jamming these long bullets into the lands may be causing some bullet integrity issues so I am testing OAL to see what happens.

    Basically I am jumping them 35 thou to the lands.

    Here are the velocity results:

    95.0...................2899 fps
    96.0...................2952 fps
    97.0...................2987 fps
    98.0...................3026 fps
    99.0...................3044 fps
    100.0..................3066 fps
    101.0..................3097 fps
    102.0..................3143 fps
    103.0..................3170 fps
    104.0..................3202 fps

    The rifle grouped at right at 1/2" ctc with the first two shots of each group. This is not uncommon with a barrel of this small contour with a very long bullet and a very large case capacity. I learned long ago that testing this type of rifle, that two shots are about all you will get with a true idea of what the rifle will do accuracy wise. Let her cool and then shoot another two and they will print tight as well.

    Looking at the fired cases, only loads 103 and 104 had any real sign of an ejector mark on the case head. And only the 104 gr load had any change in bolt lift. All loads ejected like they were not even there.

    When I got back to the bench, I was not suprised with what I found. The 104.0 gr load had slightly loosened the primer pocket. It is still a very usible case but it did loosen the pockets grip on the primer so I consider the 103 and 104 gr loads to hot for this rifle combo and consider 102.0 gr as the max working load for this rifle in these conditions.

    That said, next test will be long range stability so I am going to reload these cases with 101.0 gr which should average right at 3100 fps in this rifle and test them at 800 yards to see how they perform to give a true understanding of how the 1-9 twist is spinning these big bullets.

    Just for comparision, in the rifle I used last fall hunting in Canada, 103 gr WC872 produced 3175 fps with the same bullet but in a 30" barrel. My new rifle with this new load will easily get within 25 fps of this load with 3" less barrel length and 4 lbs less rifle.

    As to the recoil of this rifle fitted with one of Shawn Carlocks small diameter brakes, it is not all warm and fuzzy but I would class the full tilt loads in the same class as a 270 Win load at the most in a 7 lb rifle. You know it goes off but its easy to handle and shoot accurately.

    I did take the brake off for the 104 gr load and recoil was noticably more then a factory sporter weight 300 RUM loaded with a 180 gr pill to 3350 fps. It wakes you right up, put the brake right back on after that!!! /ubbthreads/images/graemlins/grin.gif

    I am very impressed with this brake design that Shawn has come up with. For its small diameter, it does a VERY good job controlling recoil especially on a rifle of this weight and this size of chambering.

    All in all, first test was a success, now onto serious testing, 800 yards. This will tell the story!!!

    More to come soon, I hope to get out early in the morning for this test.

    Good Shooting!!

    Kirby Allen(50)
     
  14. 41mag

    41mag Well-Known Member

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    " Conditions were 65 degrees with 90% humidity!!! "

    Man the rifle looks great and sounds like it shoots up to par so far. As for the conditions, I wished it was like that around here.

    For most of my development, the 65% would have been like sudo desert, and the 65 degrees, well we might see that sometime mid to late Oct.

    Last trip to the country to shoot drops, it was 78 degrees at 7:00 am with 100% humidity, then it warnmed up to about 98.