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Posted: 8/22/2015 8:21:56 PM EDT
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So the other weekend (been about 2 weeks now) i went out shooting with a couple buddies. And I started to notice some issues with some 9mm loads I had made. The other previous outings I hadn't noticed this issue. The loads were shooting about 2-3inches high out to 30yards.
9mm 124gr Plated Bullet Win Primers 3.9gr of Bullseye. I ran the bullets through an XD9, Taurus Slim, G17 and Ruger SR9c. They all shot high, maybe I hadn't noticed it on the prior outings, but I need a little help figuring it out. I started thinking about tuning the load down a little, but then I examined my loads against some buddies reloads and some factory ammo. It seems I put a bit of a heavy crimp on them. Does the crimp really mess with the accuracy that much? Or could it be the powder? Thanks, |
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Are the rounds impacting high compared to factory ammo or the same ammo only thing that changed was the crimp. I don't know if your "accuracy" was effected but point of aim point of impact. I've found to be linked to velocity. Its not a problem if you know your holdovers.
For example all ammo shot at 25 yards, with the same gun, same day, same sights. All ammo makes uspsa minor power factor (130) for their weight. Only changes are the ammo: 115= poi is poa 124= poi is 1.5 inches high 130= poi is 2.25 inches high 147= poi is 3 inches high 165= poi is 4 inches high To me your load data sounds a little low. I thought that with a 124 grain bullet and Bullseye powder you would have needed at least 4.2 grain to make at least 1050 FPS. Do you have a chrono? |
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No I don't have a chrono, I'm trying to get ahold of one but no luck so far. I will say they shoot ok, sometimes they feel a bit more stiff compared to a factory 115gr. "Stiff" recoil goes with higher pressure and velocity. I'm betting your rounds are just going quite a bit faster than the factory/other loads you've been used to. |
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Bullet weight can have tremendous effect on point of impact, compared to "standard weight" bullets, lighter bullets impact lower on the target, heavier bullets impact higher. Long ago when I was a Deputy we carried 357 revolvers, my S&W model 66 was sighted in perfectly at 25 yards with the standard 158 gr bullet. Then the hot item was the high velocity 125 gr HP's, actual ballistic results from shootings showed it had the best terminal performance of any standard revolver caliber. One BIG problem, they shot low, really low, at 25 yards the impact was off the standard B27 man sized target, the sights on my model 66 couldn't even be adjusted to bring it to point of aim at 25 yards, as I recall, best sight adjustment was about a foot low at 25 yards, at closer ranges it wasn't as big a problem, but as long as I carried that load I had to remember to use Kentucky windage if the range approached 25 yards. Not a very good situation overall. |
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I'm having the opposite problem with my Lee 124gr. I use either 3.5 or 4.0gr of Bullseye and both shoot low from my Ruger P89. I don't know about you but I'd rather have it shooting high than low. I'm not not going to be changing bullet molds so it looks like I'll be looking for an adjustable rear sight for my P89.
Motor |
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That is why some pistols have adjustable sights.
With fixed sights, it is possible to zero the pistol just by changing powder, powder charge or bullet type. It will be a trial and error thing. For a self defense pistol, I zero with the defense load and then find a lighter handload that will hit the same point of aim for practice. In general, if the pistol is sighted for 115 gr loads it may shoot a little higher with 124 gr loads. Not enough difference to matter at self defense ranges. Crimp will not effect the velocity very much on the 9mm. |
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As others stated the crimp is increasing the pressure. Faster means a flatter trajectory making them hit higher.
Also, the added recoil ( from higher pressure) is raising the muzzle up before the bullet exits, resulting in a higher POI. Reduce the charge and lighten up the crimp, it should drop the POI enough. |
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With a handgun a faster load hit low, and a slower load hits high. It is the result of the faster round leaving the barrel sooner in the recoil/muzzle flip. I think you're a little off there. It doesn't matter if it's a pistol or rifle round, faster rounds hit higher than slower rounds with the same point of aim. It's about gravity, nothing else. |
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I think you're a little off there. It doesn't matter if it's a pistol or rifle round, faster rounds hit higher than slower rounds with the same point of aim. It's about gravity, nothing else. Quoted:
Quoted:
With a handgun a faster load hit low, and a slower load hits high. It is the result of the faster round leaving the barrel sooner in the recoil/muzzle flip. I think you're a little off there. It doesn't matter if it's a pistol or rifle round, faster rounds hit higher than slower rounds with the same point of aim. It's about gravity, nothing else. With a rifle you are correct, but not with a handgun. |
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With a rifle you are correct, but not with a handgun. Quoted:
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With a handgun a faster load hit low, and a slower load hits high. It is the result of the faster round leaving the barrel sooner in the recoil/muzzle flip. I think you're a little off there. It doesn't matter if it's a pistol or rifle round, faster rounds hit higher than slower rounds with the same point of aim. It's about gravity, nothing else. With a rifle you are correct, but not with a handgun. Please explain how handgun bullets fall "up." Trajectories are trajectories, it doesn't matter whether the bullet is fired from a rifle or pistol. This is a handgun trajectory graph. 
The only thing different from a rifle trajectory graph would be the specific velocities involved. |
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Please explain how handgun bullets fall "up." Trajectories are trajectories, it doesn't matter whether the bullet is fired from a rifle or pistol. This is a handgun trajectory graph. https://www.shootersforum.com/attachments/tech-notes/8599d1246579080-handgun-hunting-loads-critical-view-trajectory.jpg The only thing different from a rifle trajectory graph would be the specific velocities involved. Quoted:
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With a handgun a faster load hit low, and a slower load hits high. It is the result of the faster round leaving the barrel sooner in the recoil/muzzle flip. I think you're a little off there. It doesn't matter if it's a pistol or rifle round, faster rounds hit higher than slower rounds with the same point of aim. It's about gravity, nothing else. With a rifle you are correct, but not with a handgun. Please explain how handgun bullets fall "up." Trajectories are trajectories, it doesn't matter whether the bullet is fired from a rifle or pistol. This is a handgun trajectory graph. https://www.shootersforum.com/attachments/tech-notes/8599d1246579080-handgun-hunting-loads-critical-view-trajectory.jpg The only thing different from a rifle trajectory graph would be the specific velocities involved. It has nothing to do with the trajectory. When you fire a handgun the pistol causes the muzzle to flip up. The faster round leaves the barrel when it is pointed lower. The slower bullet leaves when the muzzle is pointed slightly higher. |
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Quoted: Bullets begin to fall when they leave the barrel. Faster bullets fall less in the same distance. Muzzle flip has nothing to do with it. Quoted: Bullets begin to fall when they leave the barrel. Faster bullets fall less in the same distance. Muzzle flip has nothing to do with it. It is my observation that heavies impact lower when fired from rifles, and though the results are skewed due to different powder charges, impact higher when fired from a pistol.  The Fall Bullseye league is coming up. I may try 185s and 230s out of my M1991 and note the differences. However this is interesting: http://riflemansjournal.blogspot.com/2009/05/30-caliber-riflemen.html An analysis of many years of plot sheets from 600 to 1000 yard matches shows that I, like many shooters, tend to lose points to shots "in the corners” at 2:00 or 10:00. These shots are not simply the innocent byproduct of a poorly timed pulse beat and an unseen gust of wind; they are most frequently the result of the muzzle moving in that direction just as the shot breaks – even if that movement is within the X ring. These plot sheets also show that these corner shots happen far less frequently with cartridges such as the 6BR and 6XC than with the .308 and .30-06. Do we move less when shooting small calibers? No, of course not. The real culprit is the amount of muzzle movement after the shot breaks but before the bullet clears the muzzle. This is barrel movement during barrel time (BMBT). BMBT tends to carry the muzzle in the direction in which it was moving when the shot broke. How far it carries the muzzle is the salient point of this discussion. http://riflemansjournal.blogspot.com.es/2011/04/cartridges-sibling-rivalry-308-vs-30-06.html Compared to the .308, with the same bullet weight, you feel more pressure from the handstop, but not particularly more in the shoulder. The more significant difference is the amount of muzzle movement during barrel time; when the shot breaks while the barrel is still moving, the .30-06 will usually deliver the shot a bit further from center than the .308 which has less muzzle movement. As long as the shot is broken with a still muzzle and with good follow-through, the increased muzzle movement during barrel time won't be a problem. Uncomfortable recoil isn't a concern, but the need for highly refined shot execution skills is both the limitation and the opportunity presented by the .30-06. ETA: I think it comes down to how the firearm is fixed in place. Hands aren't likely as firm as a sling and shoulder, but even a shoulder has some give compared to a vice/rail gun setup. |
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I agree that how the firearm is placed and fixed on a bench has a lot to do with the amount of rise you get. But velocity determines drop, period. Once the bullet leaves the barrel, it starts falling (admittedly from an upward arc due to the way sights work), and the faster it goes, the less time it has to fall. With a pistol round, the bullet has left the barrel before the slide begins moving, with muzzle flip coming after that.
A POI difference of several inches at 30 feet points to a substantial difference in MV, and I'd be interested in whether the OP noticed any pressure signs with those rounds that impacted higher. |
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