Ammo POI Shift (Didn't think it would be that much)

[jackal2001]

I have a high end AR-15 I put together last year. Proof Research CF 16" 1/8 barrel running a NF ATACR 4x16 in a badger C1 mount. Benched with Bipod and rear bag.
I have it zeroed for BHBB 223 75g MHP. I decided to get some Federal Gold Match Premium 77g SMKHP and upon firing 3 rounds, at 100 yards, I didn't even hit my paper target. Hum. I found out that the Federal was shooting about 3"- 3.5" inches high at 100 yards. (I didn't measure the exact distance at the range)

I really didn't think there would be that much POI difference going between the two. I'm curious to see if that is normal or not.

Federal Gold Match (Taken from Federals website)
Caliber 223 Rem
Grain Weight 77
Bullet Style Sierra Matchking Boat-Tail Hollow Point
Muzzle Velocity 2720
Ballistic Coefficient .372
Ballistic Coefficient G7 .188
Bullet Length In 0.982in. / 24.94mm


Black Hills Blue Box (Taken from MidwayUSA website)
Cartridge 223 Remington
Grain Weight 75 Grains
Quantity 50 Round
Muzzle Velocity 2750 Feet Per Second
Muzzle Energy 1259 Foot Pounds
Bullet Style Jacketed Hollow Point
Bullet Brand And Model Hornady Match
Lead Free No
Case Type Brass
Primer Boxer
Corrosive No
Reloadable Yes
G1 Ballistic Coefficient 0.395
Bullet Coating Please Select
Sectional Density 0.214
Velocity Rating Supersonic

 

[308pirate]

I have a high end AR-15 I put together last year. Proof Research CF 16" 1/8 barrel running a NF ATACR 4x16 in a badger C1 mount. Benched with Bipod and rear bag.
I have it zeroed for BHBB 223 75g MHP. I decided to get some Federal Gold Match Premium 77g SMKHP and upon firing 3 rounds, at 100 yards, I didn't even hit my paper target. Hum. I found out that the Federal was shooting about 3"- 3.5" inches high at 100 yards. (I didn't measure the exact distance at the range)

I really didn't think there would be that much POI difference going between the two. I'm curious to see if that is normal or not.

Federal Gold Match (Taken from Federals website)
Caliber 223 Rem
Grain Weight 77
Bullet Style Sierra Matchking Boat-Tail Hollow Point
Muzzle Velocity 2720
Ballistic Coefficient .372
Ballistic Coefficient G7 .188
Bullet Length In 0.982in. / 24.94mm


Black Hills Blue Box (Taken from MidwayUSA website)
Cartridge 223 Remington
Grain Weight 75 Grains
Quantity 50 Round
Muzzle Velocity 2750 Feet Per Second
Muzzle Energy 1259 Foot Pounds
Bullet Style Jacketed Hollow Point
Bullet Brand And Model Hornady Match
Lead Free No
Case Type Brass
Primer Boxer
Corrosive No
Reloadable Yes
G1 Ballistic Coefficient 0.395
Bullet Coating Please Select
Sectional Density 0.214
Velocity Rating Supersonic

If FGMM is shooting only 3 to 3.5 in high at 100 yards how come you missed your paper target at that same distance?

Unless your target was a 3x5 index card, the POI shift isn't why you missed.

 

[jackal2001]

If FGMM is shooting only 3 to 3.5 in high at 100 yards how come you missed your paper target at that same distance?

Unless your target was a 3x5 index card, the POI shift isn't why you missed.

I was shooting at an 11.5x9 standard piece of paper that had multiple small targets printed on it, the ones you download and print. Shooting at the top target went off the paper. I had to shoot at the bottom target to show impact on the top target.

 

[gunsnjeeps]

Wouldn't have expected that much difference between them.

 

[jackal2001]

Wouldn't have expected that much difference between them.

Me neither. 55g BHBB only shifts about 1 inch or so compared to their 75g. Weird. I'll have to compare it in my Mark12MOD0 next time out.

 

[Rudy Gonsior]

POI shifts has mostly to do with barrel harmonics. Some barrels like yours are going to be sensitive due to barrel profiles/materials. I’ve found Proof CF AR barrels to be finicky and inconsistent in this manner but steel barrels tend to follow the general rule that the heavier the profile the less effected the POI will be. My current DMR runs a fluted 16”HBAR, this is its 3rd barrel with this profile only difference between them was length (14.5” and 18”) Pretty much no major shift (maybe a slight shift) with between jacketed bullets, but solids are another story.

As you can see the POI between the 77gr SMK and the random 55gr Russian garbage is practically the same. M855A1 always seem to be up and to the right even with other rifles.