Does Extreme Spread Matter?

Discussion in 'Ammo & Reloading' started by Hyphenated, Jan 31, 2012.

  1. Hyphenated

    Hyphenated Well-Known Member

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    So does extreme spread really matter? Everything you read says it does. When I reload I certainly am looking for consistency, because how else can you have accuracy? But some things defy logic.

    I tagged along with a friend to his gun club on Monday. The weather was unbelievable here in the Mid-West. He wanted to Chrony some new loads and I some old ones. I have an older 35Rem that just loves the Lyman 204gr bullet mould #358315. I have a very nice shooting load using 2400 powder. I just recently swapped scopes on the rifle, so I thought this was the perfect time to re-zero and check bullet speed. I have also been working on a new load for my .41mag FG. This would be a good time to clock it as well.

    The results were surprising to say the least. The 41mag had an amazing extreme spread of 37fps with an average velocity of 1860fps. The accuracy was what you’d expect with such a uniform load. The big surprise came when we clocked the 35Rem. It turned in an average of 1752fps with a terrible extreme spread of 224fps. With numbers like these you’d think hitting a 55gal drum at 50 yards would be tough, but not so with this rifle. Most guys would be happy if their lever guns shot jacket bullets, as well as this shoots home made cast bullets.

    Attached are the pictures of both groups fired from these rifles after they were chronographed. The 35rem group is no fluke. It shoots like this all the time if I do my part. My only explanation…maybe the Chrony had an inaccurate reading on one shot, but the whole 5 shot string had a lot of variance, so I kind of doubt it.
     

    Attached Files:

    Last edited: Jan 31, 2012
  2. greyhawk50

    greyhawk50 Well-Known Member

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    If you're speaking of spread in fps, my experience tells me that it is normal. There are so many micro variances that effect velocity. Here are some of the spreads that I had while working up loads.
    .35 Rem. with 200 gr. FTX bullets.
    1930 fps
    1955 fps
    1948 fps
    1944 fps

    .35 Rem. with 180 gr. XTP
    2281 fps
    2226 fps
    2260 fps
    2254 fps

    30-30 with 160 gr. FTX
    1981 fps
    1947 fps
    1996 fps
    1988 fps

    If you hang around any Bench Rest shooters, they are very precise in everything that they do. I've been told that the powder charge is the least critical. Think of just how many kernels of powder it takes to equal a half a grain by weight????
     

  3. Rooster59

    Rooster59 Well-Known Member

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    I can't add any intelligent comments so I'll speculate that the high wind at your back that day must have died down a moment when the chrony measured the slower ones. LOL
     
  4. Hyphenated

    Hyphenated Well-Known Member

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    Greyhawk...I'd be proud to post the numbers you have on those loads. I expect some variation and that is acceptable, but my numbers were way out of the norm. I am still surprised at the accuracy. Oh well, I'll clock them again someday and see if it repeats.

    Here are the numbers on both those loads
    35 Rem. 204gr Cast
    1715
    1624
    1832
    1850
    1750

    41 Mag. 200gr JHP
    1838
    1870
    1866
    1853
    1875
     
  5. Hyphenated

    Hyphenated Well-Known Member

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    Hey Rooster....in my younger days I'd time the wind speed, my breathing and heartbeat for all my shots to achieve the best accuracy...naahh...I'm full of it. I'm lucky to hit the paper most of the time. :rolleyes: :D
     
    Last edited: Feb 1, 2012
  6. greyhawk50

    greyhawk50 Well-Known Member

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    Hyphenated:
    Your groups are outstanding. :)
    Your 41 mag. velocities are fairly consistent. ;)
    You've got a huge variation in your .35 rem. :confused:
    To achieve those velocities, I assume that you are using gas checks and also assume that, to install the gas checks, you are running them through a sizing die. Cast bullets (as I'm sure you know) have many, many inconsistencies and casting imperfections. Any of which could effect the velocity but I can't see it being that much.
    Edited; I like a good mystery.
    After giving this some thought. However, your high to low variance is 226 fps.
    Your powder charge would have to differ by more than 2 grains to achieve that variance. So. I would rule that out. Any inconsistencies in the bullet that would cause pressure to bypass enough to effect the velocity that much, I would think could be seen with the naked eye. I'm thinking it's not the load.
    The only thing that comes to mind is the Chronograph. Is your bullet path at the edge of the photo eye sweet spot or is it center? Is the bullet path at the proper height above the eyes? Is the Chrono far enough away to not be effected by the barrel blast? Are the photo eyes properly shaded? Is the sky sunny, cloudy or passing clouds? Does your Chrono have a good battery? Are you moving your rifle between shots?
    You know that I'm guessing. Just trying to make suggestions that might help.
    If you find the answer, I'd be curious to know.
    You trust your load and you trust your rifle. What else is part of the equation?

    Grey
     
    Last edited: Feb 1, 2012
  7. oldbrass

    oldbrass Well-Known Member

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    from what I understand there are no two bullets on earth that shoot the same, even the slightest difference in crimp will change fps as will barrel temp and 100 other variables. I`d be very happy with those groups
     
  8. Rooster59

    Rooster59 Well-Known Member

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    Yeah, you're full of it.
     
  9. greyhawk50

    greyhawk50 Well-Known Member

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    As in the movie "# 5 is Alive", - "Need More Input".
    At what distance were you shooting to achieve those groups??
    We can rule out the Rifle, after all, it's a Marlin. Right??
    Powder is powder and I doubt that you were missing the desired charge amount by 2.0 grains.
    Variations in the crimp will change chamber pressure & velocity. But by 226 fps? :confused:
    Are the cases all trimmed to the same exact length? If not, this would cause variation in crimp pressures.
    Do you cold quench your cast bullets after they are molded? Did all of the bullets come from the same batch of lead? Do you recycle bullets until the mold is hot to prevent defects due to cold casting?
    We are all in a learning curve regardless of years of experience. You may know all this but there isn't any way for me to understand unless you tell me. Don't mean to offend. Just trying to understand and maybe help.
    Grey
     
  10. Hyphenated

    Hyphenated Well-Known Member

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    Greyhawk,
    My thought was the Chrony also. It was in the shade because the sun was behind us and the roof created a shadow. It was placed 8ft in front of us, which is what I normally do unless shooting magnums and than I go 10 or 12ft. We shot 7 different loads that day and only my 35rem was squirrely. We were shooting from a Lead Sled, but there is always some re-positioning between shots, so I haven't ruled out shooter error.

    You are right those bullets are gas checked. I use mostly wheel weights ( not real scientific ) and do not quench. I use two casting blocks at a time. I discard the first 5 or 6 bullets in each mould and then when things are going good I alternate to keep from over heating. If frosting occurs I slow down a little. I examine the bullet the next day and cull and defects. The bullets air dry for at least two weeks so they are stable before I size and lube.

    The biggest fly in the ointment here is I'm almost done with this batch of bullets and I'm going to have to start casting again soon. I only have a handful left. I do my casting out in the garage so the fumes aren't an issue, which limits my casting to Spring and Fall, so the heat and cold aren't a problem.

    At this point I think I will have to chaulk it up to Chrony error and wait until I have enough new bullets to give it an honest try in the future. My other thought was the RCBS Uniflow missed a beat and short charged the round that clocked 1624fps, because that shot was way out of the norm. Funny thing is...if I didn't own a Chrony and was shooting those groups I'd be thrilled. :D
     
  11. Hyphenated

    Hyphenated Well-Known Member

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    Hey oldbrass...I am happy with those groups, just not real sure how I managed it.:eek: :D
     
  12. axxe55

    axxe55 Well-Known Member

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    hyphenated, with those type of group sizes, i would be tickled to death! good shooting. but in all seriousness, as the others said, there can be so many different variables with cast bullets, that i wouldn't be as concerned, especially with the group size you are able to achieve.
     
  13. Hyphenated

    Hyphenated Well-Known Member

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    Axxe55....I don't think I'll lose any sleep over it. As long as it keeps shooting the way it is grouping, it's hard to determine what to change. I'm a firm believer in bullet placement over speed. I doubt a deer would be able to tell the difference between 1700fps and 1800fps when a 200gr 35cal bullet goes sailing through him. Thanks for the encouragement.
     
    Last edited: Feb 2, 2012
  14. duster066

    duster066 Well-Known Member Supporting

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    Interesting stuff. I only have two years of reloading and casting experience so I know little, but I didn't see anyone mention this. When I'm working up a load for best precision I weigh each slug to eliminate any with internal flaws. However with those groups I would doubt that was an issue. With my plinkers I don't bother, and as you all know I can tell when I get a bad one as it flies off into LA LA land.
     
  15. Hyphenated

    Hyphenated Well-Known Member

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    duster066...
    You are right it is a very good idea to weigh your cast bullets. I'll sometimes check a couple in a new box of factory jacket bullets. You never know. I bought a box of 200gr pistol bullets one time and they all were on the light side of 200. Most of them were 195grs. Since they were all about the same it didn't hurt accuracy, I just thought it was interesting.
     
  16. axxe55

    axxe55 Well-Known Member

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    the variance in bullet weights can be more so with cast bullets than jacketed bullets. most of the major bullet makers are pretty consistent with bullet weights. doesn't hurt to weigh them just to be sure of the weight, as they could also be mismarked or mispackaged. it does happen sometimes.