Another 200 gr ULD RBBT velocity/accuracy test........

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Fiftydriver, Jul 22, 2005.

  1. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    Just got finished testing a batch of 7mm Allen Magnum rounds loaded with the 200 gr ULD RBBT in the 26.5", 1-9 twist Shilen #4 barrel.

    I started with 94.0 gr, increased by 1.5 gr up to 100 gr and then by 1.0 gr up to 104 where I stopped.

    Here is the target from the testing, this was at 100 yards, hay bails were in the way for my 200 or 300 yard shooting allies!!!

    [​IMG]

    Shots 1-3 were shot at the middle square, 4-6 were at the right and 7-9 at the left. I would also like to point out that shot number 7 was my fault. I have been nursing a pretty serious pinched nerve in my right shoulder/neck area and it got away from me on that shot, flinched like a little girl. Had I not I suspect that three shot group would be as good or better then the 4-6 group.

    Once velocity got to +2950 fps in this barrel, the groups really tightened up, dramatically so in my opinion. I was glad to see the extremely consistant velocity increase with each increase in powder charge. Seemd this bullet and powder are a good match for this case volume!!

    Velocity wise I was happy as well. My original predictions were to hit 3200 fps in a 30" Lilja 3 groove barrel. This shorter barrel hit 3140 fps with the 104 gr load. Still I wanted to see how the primer pockets were holding up so headed back to the bench and popped the spent primers out and reprimed the cases. The 104 gr load felt EXACTLY like the 94 gr load.

    There was a slight pull on the bolt handle needed to extract the cases. From past testing with the other Allen Mags I am 100% confident that this is because the cases were not partially full length sized and more importantly, I did not reanneal the case necks before loading these more serious loads.

    In past testing, these two things totally eliminated the slightly sticky case extraction and also allowed slightly higher velocity potential as well. We will see. I will not test higher until I get the Redding Full Length Sizing dies in stock so I can partially size the cases to correct this problem and so I can get an accurate idea of case extraction.

    Still, 3140 fps with a 200 gr ULD RBBT in a 26" barrel is enough to make me smile.

    Group 4-6 measured .778" ctc. Shots 8 and 9 were .521" ctc and I suspect had I not flinched on shot 7 that group would have also been in the 3/4 moa range.

    Certainly not amazing but for this bullet in this twist barrel in this light of a barrel, I will take it anyday of the week!

    I will second what ss7mm posted about rifle torque with these bullets, at +3000 fps it will lay the rifle on its side if you are not doing your job. The Holland QD brake helps alot but there is no way around this.

    More testing to come at longer ranges. Please to not take this test as saying the 200 gr ULD will work in any 1-9 twist barrel, it may well not. Hell, it may shoot 10" groups at 300 yards in this barrel, I will test and report my findings.

    It does however tell us that there is a decent chance that this bullet may be usible in factory, large cased 7mm rounds!! WHat a boon that would be to 7mm shooters.

    Nuff playing for today, back to work I go!!!

    Good SHooting!!

    Kirby Allen(50)
     
  2. jb1000br

    jb1000br Well-Known Member

    Messages:
    1,307
    Joined:
    Jul 8, 2003
    Kirby --I bet $$$ these brakes would help the torque situation...

    and can be had for 30$ /ubbthreads/images/graemlins/wink.gif

    [​IMG]

    lemme know if interested /ubbthreads/images/graemlins/wink.gif

    JB
     

  3. Buffalobob

    Buffalobob Writers Guild

    Messages:
    5,085
    Joined:
    Jun 12, 2001
    Looks pretty good.

    I ran some numbers which I am sure you will run too. I was trying to see if you were still getting good increases in velocity at 104 grains.

    7 AM 26” barrel
    Load gr Velocity fps/gr
    #1 94.0 2837fps
    #2 95.5 2873 24
    #3 97.0 2924 34
    #4 98.5 2969 30
    #5 100 3000 20
    #6 101 3051 51
    #7 102 3096 46
    #8 103 3115 19
    #9 104 3140 25

    The ending numbers look about as good as the beginning numbers. About 20-25fps increase in velocity for every grain of powder increase in a standard groove and lenght barrel.

    It is always good when you see the light and know that it is the end of the tunnel not a train.

    Thanks for the update.
     
  4. ss7mm

    ss7mm Writers Guild

    Messages:
    3,707
    Joined:
    Jun 11, 2005
    Kirby:

    I noticed the same thing in my ladder test, and that is when the WC872 loads got up towards the top of the useable range the spread tightened up. In fact the best node in the top half of the loads was at the 2 highest loads I tested.

    I’m going to try and get everything loaded up for groups and some more increased loads also, and get them tried in the next few days.

    3140 fps in 26.5” of barrel looks like your 3200 fps will get bypassed as soon as Dan gets the new tubes done. That’s great news.

    If those bales you mentioned are what I saw all over Montana they are the rounds that are about the size of a buffalo. I can see how they could be in your way.
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    Buffalobob,

    Yes I was impressed by the consistancy of the velocity gains per grain of powder. For this capacity size, it is not all that often you see such a steady increase with only 1 to 1.5 gr of powder increase. I am sure this is due in large part to the quality of the brass and tight throat.

    The throat length on this reamer is just about perfect for the long 200 gr ULD bullets as well. Being 3.620" or so in OAL and still being off the lands 0.010" to 0.015" gives plenty of room in the Rem length mag box.

    So far so good.

    Kirby Allen(50)
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    ss7mm,

    TO be honest, I would have been happy with 3000-3050 fps in this barrel length. Even if I can go no higher with good reliability which I don;t believe is the case, I am totally satisfied with this level of performance.

    In a 30" barrel I suspect she will push 3300 fps VERY hard, espeically in the 3 groove Lilja. But there is no need really. The 270 AM is doing great work with the 169.5 gr ULD at 3260 fps. I know for a fact the 7mm AM will get the 200 gr ULD going this velocity, plus you have the significantly higher BC, which is yet to be established for those out there worried about BCs!!! /ubbthreads/images/graemlins/grin.gif

    The WC872 has always performed best in the top 5% of load pressures for me in the Allen Mags. It also burns much cleaner in this range. Lower pressure and its a coal factory. I suspect you will run out of case capacity before you get into high pressures with the Wby case. Curious to see how fast you can go though. If you get to close to the AMs performance, please don;t tell me!!!! /ubbthreads/images/graemlins/grin.gif

    Have a good weekend,

    Kirby Allen(50)
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    jb1000,

    Do they have a solid bottom design for shooting prone?

    I have tested alot of brake designs similiar to those and never got the recoil reduction like I get with the Holland. They tend to be a bit quieter but if I am going to use a brake, I have committed to the fact that it will be louder then a clean barrel so why not get the most recoil reduction possible.

    Recoil now is in the 243 Win sporter rifle range. The reason the rifle torqued so much is because I started shooting like I generally do, BR style, barely holding the rifle. Supporting the forend with my off hand greatly reduced this torquing, still, it was noticable.

    Do you make those brakes? Quality looks great, how do they cut recoil compared to a partition style brake?

    Kirby Allen(50)
     
  8. jb1000br

    jb1000br Well-Known Member

    Messages:
    1,307
    Joined:
    Jul 8, 2003
    Kirby -- made at my request by Kregg Slack -- he will do whatever you want (within reason) for 30$ /ubbthreads/images/graemlins/wink.gif www.parrysgunsmithing.com

    Im sure he could put the helix on just the sides, and leav top and bottom un touched...worth trying for 30 bux /ubbthreads/images/graemlins/wink.gif

    any thread, contour finish /ubbthreads/images/graemlins/wink.gif

    cant comment on comparison, as all my brakes are on different classes of rifles.

    JB
     
  9. sscoyote

    sscoyote Well-Known Member

    Messages:
    1,255
    Joined:
    Feb 26, 2003
    I thought those looked like Kregg's. He just put together a 243 WSSM Savage Striker for me, and we had to put a break on it to reduce recoil enuf to effectively use the 4.5-14X Leupold VX-III i mounted on it. Now i can get full FOV from prone- no problem. Before it was touching my forehead with full power 100 gr. loads @ 1/2 the FOV.
     
  10. 7Rumloader

    7Rumloader Well-Known Member

    Messages:
    540
    Joined:
    Jan 20, 2005
    Thats great Kirby! Looks like your goal of 3200 will be easy to obtain with a 30 inch Lilja.
    Your tests in the 9 twist makes me feel very optomistic about my Rum stabilizing them until I can get a 7mm AM in my hands.
    I never dreamed I would be shooting 200 grain pills in a 7mm over ten years ago when I bought my first one. /ubbthreads/images/graemlins/shocked.gif
    Keep us posted.