Bullet impact differences

[Dragon11]

I'm hoping someone can explain this to me. I currently shoot a Glock 34 with Trijicon sights in production division. My load is 147g Bayou bullets with 3.5 grains of PB powder. At 25 yards by bullets are grouping 6 inches high consistently, point of aim point of impact. When I go out to 50 yards, they hit about 8 inches high. If I shoot the same gun with factory ammo, Federal 115g, the bullets hit dead on point of aim point of impact, at 25 yards. Can the bullet weight change the point of impact from point of aim that much? I have also loaded with Super Target powder and had the same results.

[Steve RA]

The heavier bullet has lower velocity, stays in the barrel a little longer and exits at a higher point in the recoil.

[SPDGG]

fwiw:

If you stick with that load and prefer a lower POI, need to swap to a "taller" front sight height.

* * * Dawson Precision site for Front Sight Height Calculation:

http://www.dawsonprecision.com/CategoryProductList.jsp?cat=SIGHTS+FRONT

Dawson Precision offers various Glock Front Sight Heights & Types:

http://www.dawsonprecision.com/CategoryProductList.jsp?cat=SIGHTS+FRONT%3AGlock+Front+Sights:Glock+Standard+Front+Sights

-or- swap to a different sight setup:

Warren Tactical

http://www.shootersconnectionstore.com/Glock-Sights-C455.aspx?m=68

Taran Tactical

http://www.shootersconnectionstore.com/Taran-Tactical-Ultimate-Fiber-Optic-Sights-Set-for-GLOCK-P2840.aspx

Dawson Precision

http://www.shootersconnectionstore.com/Glock-Sights-C455.aspx

^ Choose Front Sight Height from description above

Edited July 25, 2014 by SPDGG

[Dragon11]

I'm getting some 124g Bayous sent out to me to try. I'm glad I asked, my twisted logic had me thinking I needed to order a heavier bullet. If I can stay with the same style of sights and adjust my load a little bit, I'll be happy with that.

[njl]

The heavier bullet has lower velocity, stays in the barrel a little longer and exits at a higher point in the recoil.

I guess that makes sense...because other than that, a heavier/slower bullet should drop faster, so they should be hitting low, not high...and not even higher at greater distances. Perhaps a firmer grip (trying to resist muzzle flip) is in order?

[TCWriter]

I've seen the same effect (slower rounds impacting higher) on my G34 and G19, and assumed the "time in barrel" explanation was the reason.

Fortunately, my G34 sights (Sevigney with the tall front FO) are right on with the 147 match loads. My G19 carry gun (Warren night sights) shoots a little high with 147 grain defense loads, so I'm ordering some 124 grain defense rounds to see if they are closer to point of aim.

Good luck.

[jcc7x7]

In my 40 2011 and Para

200 gr bullets hit 3 's higher than 180's both loaded to 172-173 PF

Same Same

[Hi-Power Jack]

I've had same results.

In addition, I've seen heavier or lighter bullets hit left or right ...

Don't recall if the heavier or lighter bullets hit to the left, but I believe

it's the heavier bullets tend to hit left in my BHP. (Guess it would

depend on whether the rifling is clockwise or counterclockwise).

[b1gcountry]

I wonder if a heavier recoil spring assembly would help solve this...

[Steve RA]

Adjustable sights are the best answer - determine the load you want to use - adjust sights - Presto, home free !!!