Please Help Me Develop a Load for 145 GR LRX in 7 MM WBY Magnum

Discussion in 'Reloading' started by chesspunker, Jul 7, 2018.

  1. chesspunker

    chesspunker Well-Known Member

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    I'm looking for reloading tips for a 145 GR LRX Barnes Bullet in 7 MM WBY Magnum. I know my gun likes the 140 GR TSX Weatherby Factory ammo. I decided to try loading the LRX because it gets a lot of good reviews. Here is what I've done so far:

    Used only once fired Norma Weatherby Brass and Neck Resized Only. The necks all measure within 0.001". I trimmed my brass to recommended length +/- 0.001" and then deburred using RCBS VLD tool.

    GM215M Primers

    RL 22 Powder (my ladder test held 3200 FPS +/- 3 FPS when using 69.9 to 70.3 grains of RL 22 so I loaded my first test batch at 70.1 grains.

    I seated my bullets so the OAL was as long as the magazine accepts 3.375". My first shot was from a cold clean barrel. My next three shots were about 2" away from the first shot but they held a 1/2" group. My fifth shot unfortunately was where my first shot was about 2" away from the nice tight group that shots 2-3 produced.

    There is a chance for operator error of course. However, I'm wondering if the next time I go to the range I should wait 15 minutes (or until my barrel completely cools) for every single shot. For my session, I would shoot three shots then wait 10 minutes then shoot two more shots. The barrel never got hot, but it was definitely warm to the touch which I've heard is a no no with Weatherby.

    I also noticed that my seating die bottoms out on the bullet plastic tip rather than the ogive which I heard can definitely cause error. Before I load up my next batch I'm going to have RCBS help me fix this problem.

    I'm looking for any and all advice that experienced reloaders can give me to help me develop a sub MOA round for this rifle.

    Thank you!
     
  2. cape cove

    cape cove Well-Known Member

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    I own a 7mm Wea mag and one of my best loads uses the 145 LRX. My load is 74 grs of Norma MRP lit by a Rem 9 1/2M primer in Weatherby brass. My OAL is 3.370 and vel is 3327 ft/sec. Accuracy is .760 at 100 yds. Good load. This load is a max safe load in my rifle. Reduce and work up carefully if you try this. Some loaders believe that RL-22 and MRP are the same. In my loading this is most certainly not the case. They are similar but not the same. Hope this helps you
     
  3. chesspunker

    chesspunker Well-Known Member

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    Thank you very much. This really helps me and I will try Norma if I can’t find it with RL 22.

    I had another harmonic node at 3300 FPS when I used 71.1 to 71.5 grains of RL 22 and I showed no signs of over pressure. I’m going to load my next trial batch at this speed using 71.3 grains to get closer to your velocity.

    Can you please explain your process for shooting your .760 groups at 100 yards? Do you count your first shot from a cold clean barrel? Do you wait until your gun completely cools down between shots? Do you clean between firing different groups or do you wait until you get home and clean after the shooting session? What is the maximum number of rounds you shoot between cleaning?

    Also do you use a lead sled type rest from the bench? Once again I greatly appreciate your help!
     
  4. Andrew Massi

    Andrew Massi Active Member

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    My 7mm bee shoots the lrx best over a stout dose of retumbo. Velocity is 3350avg, fed 215m primers, 3.30 coal, extreme spread of 12. I find retumbo to be one of the most stable powders in the 7mm bee.Avg .750
    but more importantly for me anyway, they stay sub minute of deer vital out to 800

    I prefer the cut from the lyman vld tool over the rcbs

    I always count the cold bore shot, especially in a hunting rig.

    I shoot 3 rounds pretty quickly say within 1 minute max of each other. As long as it takes to pull the brass, set it in its basket and drop another round down the pipe. Check natural point of aim, breath control, sights settle, slow steady squeeze.

    The next group will be 15-20 minutes later, barrel is normally completely cool

    I Always shoot through a "seasoned" or fouled barrel, for me there isn't a set # of rounds between cleanings I just keep shooting until accuracy starts to degrade then I deep clean, condition and re foul
    "Range" work is as limited as possible and rounds are used on down range gongs and rocks in hunting situations and positions.


    I use a front bipod and rear bag, sometimes I'll use a Caldwell rock jr front rest and rear bag if I cant shoot prone. Either set up allows you the rifle to recoil in a straight line and not jump around

    I don't use a lead sled because it has no shooting mechanics, also when I tried them in the past I always had to adjust my zero after, the sled would be 4-5" off of my natural point of aim.

    If recoil sensitive I'd really recommend wear a pad or shooting jacket, or get your barrel threaded for a brake.

    The biggest thing with barnes bullets and a weatherby throat is playing with oal.
    Sounds like you found a velocity mode, I'd just tinker with oal until you notice it tighten up
     
  5. chesspunker

    chesspunker Well-Known Member

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    Thank you Andrew! When playing with OAL what increments do you use to help save time? If I start long then how much would you shorten for your next group?
     
  6. chesspunker

    chesspunker Well-Known Member

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  7. cape cove

    cape cove Well-Known Member

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    I usually foul the barrel with a round before firing a group of three if the barrel was cleaned. I never use the fouling round to count in my group, but count the first round if the barrel has been fouled. I always take my time shooting so as not to heat up the barrel. I use sand bags up front and rear when shooting. I tried the lead sled, but just don't like it at all. I found that by free floating the barrel ( removed the pressure point ) I got better groups. My advice concerning the OAL would be to start at max magazine length and shorten ( maybe .020 at a time) till you hit a good length, then you can adjust it till you get your best accuracy.
     
    Last edited: Jul 7, 2018
  8. chesspunker

    chesspunker Well-Known Member

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    Thank you Cape!
     
  9. chesspunker

    chesspunker Well-Known Member

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    Hi again Andrew. The only reason I’m considering going to my higher velocity node is because it seems like everyone who says they shoot Sub MOA with the 145 grain LRX is at or above 3300 FPS. I’m worried that 3200 isn’t hot enough. I’m new to the reloading game and it’s quickly becoming an obsession so feel free to chime in again and set me straight.
     
  10. chesspunker

    chesspunker Well-Known Member

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    After chatting with someone from Barnes, he seems to think that I'd be better off going with H4831SC Powder because my gun probably doesn't like RL22. When I did my ladder test using RL22 I never shot from a heated barrel and the group size for 10 shots was about 3". He said that shouldn't happen.

    Has anyone had any luck with H4831SC?

    I hunt Napa in California in 90 - 100 degree heat and then I hunt out of state in freezing temperatures so H4831SC is a better choice for resisting temperature swings.
     
  11. cape cove

    cape cove Well-Known Member

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    I've never tried much of this powder in mine , but it would seem to an excellent candidate for this caliber. Keep in mind that factories test their ammo in all conditions so as to supply their customers with the best ammo possible although mass produced. Norma makes Weatherby ammo, and i'm sure they use one of their powders although probably a non canister grade of one of them.
     
  12. chesspunker

    chesspunker Well-Known Member

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    Thanks for all the help!
     
  13. chesspunker

    chesspunker Well-Known Member

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    I'm heading to the range today to test for velocity using H4831SC powder! I started at the minimum call out on the recipe and went up in 0.5 grain increments. Once I get to around 3300 FPS I'll head back home and load up a ladder test for tomorrow. I'm hoping to find a velocity node around 3300 FPS and then I'll load up for accuracy testing at the center of the highest velocity node that I find (under the max pressure of course). Using the ballistics calculator the higher the velocity the more stable the round will be. My 1:9" twist custom stainless barrel is supposedly plenty good enough to make this very stable according to the Berger calculator.

    I'm very happy because the Forster Ultra Micrometer seater die has eliminated my runout problems. I started by measuring case neck runout. With my neck sized Norma WBY brass, most runout is only 0.0005" - 0.001" which is almost nothing. A small percentage of my cases has a runout of about 0.002" - 0.0025". For velocity testing I used my cases with the increased runout. After seating with my Forster die the runout didn't increase! That die really puts them in straight! I pulled the handle super slowly and smoothly on my Rock Chucker while seating and stopped three times per seating to spin the case 90 degrees before fully bottoming out the press.

    Thanks for all of the help!!! I'll keep you posted on my journey.
     
    Last edited: Jul 18, 2018
    Andrew Massi likes this.
  14. chesspunker

    chesspunker Well-Known Member

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    I was surprised by my velocity test yesterday for my quest find out where my max load weight for H4831SC is. When I initially tested with Reloader 22, I was at 3300 FPS when I hit 71.1 grains of powder and for that Barnes recipe, the max load is listed at 74.5 grains of powder. I was close to maxing out and was still more than 3 grains from the max with RL 22.

    I was anticipating the same sort of thing with H4831SC, but what I found is that changes in powder weight with this powder produce way less velocity change. The Barnes recipe calls for the minimum with H4831SC to be 66.5 grains and the maximum to be 73.0 grains. Below is every speed for every shot:

    66.5 grains = 2872 fps
    67.5 grains = 2999 fps
    68.0 grains = 2967 fps
    68.5 grains = 2960 fps
    69.0 grains = 3022 fps
    69.5 grains = 3040 fps
    70.0 grains = 3059 fps
    70.5 grains = 3087 fps
    71.0 grains = 3067 fps
    71.5 grains = 3106 fps
    72.0 grains = 3140 fps
    72.5 grains = 3170 fps
    73.0 grains = 3173 fps

    I show absolutely no signs of over-pressure so I'm going back to the range today. I loaded up 9 more rounds starting with 73.5 and going up in 0.5 grain increments. I will be very careful shooting these rounds and as soon as one of them gets very close or slightly above 3300 FPS I will stop. Even at my highest bullet weight of 77.5 grains (I may not shoot that bullet today) I can still hear the powder shaking in the case so I don't think it's compressed.

    Yesterday I shot three shots in a short period of time and then I would wait 20 minutes until my barrel completely cooled for the next three shots. All of my shots except for one of them was in a vertical line. The first shot from a dead cold barrel was the highest shot. The next shot would be about 1" lower and the third shot would be about 1" lower than the second. They were all in a vertical line with almost no side to side displacement. I'm not sure if this means anything since each shot had 0.5 grains more powder than the next.

    When I find a velocity node and test for accuracy I'm going to let my gun completely cool down between shots. I also won't have the chronograph strapped to my barrel which might change the way my barrel shoots especially if I let it get hot.

    Feel free to comment on this post especially if you have anything to add about safety precautions I should take on my test today as I try to find 3300 FPS.