velocity vs accuracy

Discussion in 'Reloading Room' started by 60ratrod, Apr 24, 2014.

  1. 60ratrod

    60ratrod STFU CARL! Member

    so i'm wondering if a bullet with more fps is more accurate than a bullet of the same weight and caliber that is going slower with less fps? i recently switched powders in my pistol loads from bullseye, cause i can't get that stuff, to 700x. and i'm really liking the 700x. but to get more accuracy, do i need to heat up the load a bit more? this is for my 9mm loads
     
  2. ajole

    ajole Supporting Member

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    This is a huge area of debate, but here's the basics.

    As long as the bullet doesn't go from supersonic to subsonic between the barrel and the target, it stays more accurate.

    If, somewhere between you and the target, it drops out of supersonic...like MANY .22 LR bullets do when shooting at 100 yards or more...that's when things destabilize and get erratic.

    Bullets with a nice high ballistic coefficient, like the .338 Lapua and some .270 projectiles, tend to stay more accurate at longer distances, as they maintain speed better for longer distances. This is reflected by less wind drift, and better stabilization out at longer ranges.

    High BC bullets are found in the .25-06, 6 mm series, .270, the heavy 7.62mm stuff (as shot from the .300 WinMag) and all the long range military stuff like the .338 Lapua, .375 Chey-Tac, .416 Barret, and the .50 BMG.

    SOooo...

    Either shoot fast enough to stay fast, or shoot slow subsonics at closer ranges, which is why .22 target shooters like the shorts.;)

    In a 9mm semi gun, to operate the action properly, you will probably need to either go fast, or go slow with a heavy bullet.
     

  3. SWO1

    SWO1 Member

    Generally speaking .....NO. A lot depends on the gun and the load (bullet) and what are you shooting, Bullseye Target or USPF.

    For best accuracy most all shoot 9mm (or any centerfire pistol )with heavy bullets SLOW. Around 650 fps at 25 to 50 yards. Also crimp is a big part. Just enough to take the bell out of the case mouth.m Bullseye is a favorite powder for 9mm target.

    Inside of 25 yards shooting at steel, or for self defense it a whole different set of variables, best accuracy isn't one of them.

    Change powder, bullets, brass, primers and for any particular gun accuracy changes. I recently improved my .38 super loads just by changing primers. Went from a small pistol (CCI 500) to Winchester small rifle and things improved with all the other components staying the same.
     
  4. I didn't know that about primers going from small pistol to small rifle primers. Nice tip! Is that relevant to powder types. slow vs faster burning rates?
     
  5. 60ratrod

    60ratrod STFU CARL! Member

    Aren't small rifle primers just a little hotter than small pistol primers, like hardly enough to make a difference? And my current load is about .2 lighter than the hogdgon recommended for 124gr 9mm plated/cast projectiles, but cycles just fine. Maybe I'll warm the load up a tad and see how that works. When I shot a test batch, they were kinda all over the place, but all inside the target for the most part at 10yds.
     
  6. SWO1

    SWO1 Member

    Not really. Small pistol and small rifle are interchangeable in PISTOL only. Large pistol and large rifle are NOT !! Even tho they both are the same diameter the large rifle is TALLER and wont seat flush in a pistol case.

    I am using Titegroup for the .38 super (as well as for .45 acp). Sierra loading manual specifies Win small rifle for all the .38 super loads across a wide range of powders.

    Generally Small Rifle is about like a Small Pistol Mag primer. The caps are a little harder and some guns may have an ignition problem. Changing to a heavier firing pin spring or tuning the innards a little may be needed, again depending of the gun.
     
  7. SWO1

    SWO1 Member

    All components make a difference. Depends on what application you are shooting. At 10 yards proabely not a big difference. At 25 yards .1 of a gain of powder makes a BIG difference in my bullseye gun, For self defense or shooting plates or body targets only taking about less than .2" difference.

    But that's my gun. For your application and gun just have to work up a load that meets your expetations.

    My self defense (carry gun) I load up for POWER and Penatration. Different powder, different bullets. At 7 yards can keep them all in the 10 on a B-7. First place in a gun fight has a different prize than in a Target Match ..... ;)
     
  8. Branth

    Branth Member

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    For rofles, I have generally found that hot loads shoot more accurately than light loads, if you've tuned them well. There have been exceptions to that, though - With Benchmark powder in my .308 shooting 150gr GameKings, I'm getting peak accuracy with lower powder charges.

    With a 9mm though? I doubt there's any significant difference. Out of a handgun, you'll probably never shoot to the accuracy potential of the gun, let alone the ammo (unless there's something crazy going on like undersized bullets or poor stabilization). Even out of a carbine I'd wonder how much of a difference it makes.

    The most important things for accurate loadings in my experience are the following two:

    1. CONSISTENCY in powder charge. This is HIGHLY important. When I'm loading for accuracy, I trickle every charge to the proper weight. It takes time, but gives you smaller velocity differences, and therefore more consistent shots.

    2. Tuning your load. As powder charge increases, I've noticed a general "sine wave" pattern. Accuracy increases, then decreases, then increases, etc. Most of the time it seems to me that it gets gradually more accurate as you increase charge, but every once in a while I've found one that goes backwards. You'll see more improvement from tuning a load to be in the most accurate part of the wave than you will just upping the powder charge and hoping for the best.

    Standard caveat: This is all my personal experience, and your gun/bullet/powder/zen state may be different. Test it out for yourself and see!
     
  9. 60ratrod

    60ratrod STFU CARL! Member

    Well I think I'm going to increase the load just a little bit. I wanna try to tighten the groups a bit is all
     
  10. forgotenpast

    forgotenpast Member

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    go up progressively by 0.1gr until you approach top of the spectrum
     
  11. ajole

    ajole Supporting Member

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    You do realize that everyone who said go faster was talking about rifles, while the two that talked pistols suggested slower/heavier?:p
     
  12. Branth

    Branth Member

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    If you're using 700X, you might have trouble with accuracy just because it meters like constipated gravel. Be sure to tap the bejesus out of your powder measure to settle it when you drop a charge. If you really want peak accuracy, I'd trickle-charge.
     
  13. 60ratrod

    60ratrod STFU CARL! Member

    Oh I know how it hates to meter. I have to smack my lee autodisk around like bobby and whitney to get a good charge
     
  14. 60ratrod

    60ratrod STFU CARL! Member

    also, i'm using 124gr plated 9mm slugs, so i need to keep these slow?
     
  15. ajole

    ajole Supporting Member

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    If they are under 1100 fps at sea level, its probably OK, but under 1000 fps is better.

    The problem is, at slower speeds, the powder is less, meaning smaller variations in the charge are possibly a higher percentage change, meaning they are possibly less accurate.

    100 fps isn't much change at 3000 fps, but 100 fps is a LOT of change at 800 fps.

    So, as Branth said...meter the heck out of the drop, trickle is probably best.

    If you can't get a good steady drop, then MAYBE faster would be the answer. I've seen recipes that went about 3.9 under Berrys 124 plated.
     
    Last edited: Apr 25, 2014
  16. 60ratrod

    60ratrod STFU CARL! Member

    i got the fps of the 3.5gr 700x with 124gr plated slugs, but i can't remember what it is off the top of my head. i have it written down in my bench book that i put together. it's in the 800's, i know that much. i'll look when i get home. but like i said, from my m&p9c, i was getting quite a spread on a 10" shoot-n-c sticker target at 10yds. and when i was working 9mm loads up for 700x, 3.5 is pretty much the minimum to get my m&p9c to cycle, so i think that there's room to warm up my load just a bit.
     
  17. ajole

    ajole Supporting Member

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    Yep, sounds like it.:)
     
  18. Branth

    Branth Member

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    If you want to keep them subsonic with full-power loads, get yourself some 147gr bullets. Those are around 1000fps at full power, IIRC.
     
  19. I too seen the same thing. For a good explain as to what & why of this the companies that make pressure testing equipment provide that @ their websites.
     
  20. 60ratrod

    60ratrod STFU CARL! Member

    Well the average velocity was 941.8