55 grain vs 68 grain trajectory?

SF-M1A

SF-M1A

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I recently bought a rem 700 in .223 with a 20 inch 1:9 and have been shooting a lot of cheap 55 gr ammo to good success. From what I understand this rate of twist is ideal for heavier bullets, i.e. 68 gr.

My question is will the 13 gr difference affect my zero/mrt noticeably enough to re zero?

I was hoping to just use the heavier rounds on windier days/ longer shots and use the cheaper ammo for plinking without much adjustment.
I'm in no way new to shooting but I am new to optics so any input would be appreciated.

Thanks in advance.
 
SF-M1A said:
I recently bought a rem 700 in .223 with a 20 inch 1:9 and have been shooting a lot of cheap 55 gr ammo to good success. From what I understand this rate of twist is ideal for heavier bullets, i.e. 68 gr.

My question is will the 13 gr difference affect my zero/mrt noticeably enough to re zero?

I was hoping to just use the heavier rounds on windier days/ longer shots and use the cheaper ammo for plinking without much adjustment.
I'm in no way new to shooting but I am new to optics so any input would be appreciated.

Thanks in advance.
Click to expand...

Yes it will change your zero, but that's why they put those two big knobs on the scope:p Having said that, the zero change might not be much because of barrel harmonics and velocities. I had a .270 once that shot 90 gr bullets and 150 gr bullets to the same point of impact at 100 yards. 130 gr bullets shot about 1 1/2" higher.
 
I shoot BT 55s and 69grain SMKs in my 1:9 223. At 100 and 300 the POI is different (even when I'm not wobbling :D ), but they are both on paper. So I can twiddle the scope knobs. I generally don't care as long as I can see the groups.
 
im about to try 69 and 75gr this weekend, what is the bullet drop on these at 300 yards? i get about 9 inches at 300 yards with 55gr in my 1:9 savage
 
Thanks guys.
I guess I'll buy more than a couple of boxes of these.
Oh well, this is the only purpose that can keep me smiling while working overtime.:rockOn:
 
I only get to shoot out to 100 yds so I can't say much about anything farther but I think I can comment on the zero. I've put a bunch of different bullets through my .223 Sav 25 (1 in 9) and the best weight for me is 60 to 69 gr. Anything under that doesn't shoot worth a s--t. I have had nice groups with Sierra 60 gr hp #1375 and both Hornady and Sierra 68/69 gr match HPBT's. I have also had some good groups with Hornady 75 gr match HPBT (not with 75 gr A-Max though too long perhaps).

As far as the zero goes you will prob find that the diff bullets will print in places you might not expect. They might print high, low, left, or right independent of the weight (at 100 yds anyway). Find a bullet/load you like and zero with that. If you shoot something else reg just correct with your aim and leave the zero alone.
 
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