mp sport 2 scoped shooting very low

[Newhouse]

OP, have you tried better ammo since you were using cheap tulammos. The tulammos group well at 50 yrds on my M&P15OR but looks like shot gun pattern at 100 yrds.
Bullet drop appear to be similar from subsonic 223/556 ammo,

 

[Magload]

The chamber.... funny.

Actually you can get 10 inches below line of sight at 100yds with a 40yd zero if shooting with a muzzle velocity of around 900fps instead of typical 5.56 velocity of around 3000fps. The first time the bullet would cross line of sight would be less than 30yds then cross again at 40yds. That's why I left open the possibility of the OP hand feeding goofy ammo. In any event, I think the OP made the right decision to send the rifle back. If nothing else it will give him time to think about it.

Yes i just run those figure and that would work but then I would suspect that the BCG would not lock back on the last round if it would even feed any rounds. My target AR is hand fed using a Bob Sled and when working up loads starting loads some times don't lock back. I do have the gas block adjusted so it just locks on standard loads. I think send the rifle back will answer OP questions and we will get a answer on what it was. Don

 

[Magload]

OP, have you tried better ammo since you were using cheap tulammos. The tulammos group well at 50 yrds on my M&P15OR but looks like shot gun pattern at 100 yrds.
Bullet drop appear to be similar from subsonic 223/556 ammo,

woot never thought about that they do sell subsonic 223. Don

 

[rodney winston]

tried iron sights sunday using peeps top of front post in center of rear peep ring at 40 yards put suprisenly good group 5 shots right at 1 inch but was about 8 inches over point of aim did not have tool to adjust front sight post.so could not try at longer ranges would have just been wasting ammo sent rifle off to s&w today will repost when it comes back.for the record 2 buddys bought ruger ar 15 dust cover would not latch has to return and another a ruger sr9c the trigger would not reset 1 to 2 times per clip and needs to be returned i guess all manufacturers can have issues

 

[cyphertext]

For future reference, use the tip of a round to adjust the front sight.

 

[rodney winston]

sorry on other posts

i was trying to get imput on barrel crown damage to see if its possible to cause this problem ive been shooting 35 years and this is just baffeling me because it seems impossible it only makes sense that is bad crown caused bullets to angle slightly down air pressure above and vacuum void under bullet would make bullet drop faster than gravity alone. by the way i own a s&w bodyguard and a mp40 i have no issue at all with s&w i would buy another mpsport over ruger the action just felt better to me and know this is just a 1 in a million problem.

 

[cyphertext]

Did you ever shoot at different ranges and notice if the round started keyholing? Keep us posted on the response from S&W... I'm betting that they replace your barrel.

 

[rodney winston]

yes all 3 times after 40 yard zero moved to 100 re zero from 8 ish inch low to on again then moved to 200 and was roughly 3 feet low did not hit paper at 200 but 100 yards did not have noticable keyholing and had 2 to 3 inch groups with pmc bronze tried for grouping first time out then next 2 times shooting i was not trying to group was just trying to see if issue changed with differant mounts scope ect

 

[ChattanoogaPhil]

yes all 3 times after 40 yard zero moved to 100 re zero from 8 ish inch low to on again then moved to 200 and was roughly 3 feet low did not hit paper at 200 but 100 yards did not have noticable keyholing and had 2 to 3 inch groups with pmc bronze tried for grouping first time out then next 2 times shooting i was not trying to group was just trying to see if issue changed with differant mounts scope ect

Let me get this straight.....

Groups are ok 2-3in.
No keyhole.
40yd zero = 8in low at 100yd
100yd zero = 3ft low at 200yd.

If all this is correct, this is the ballistics of a 62gr bullet with a muzzle velocity of around 900fps instead of typical 5.56 of 3000fps. Which begs the question... again... is the gun cycling or are you having to charge each round?

Are you actually shooting an M&P 15? Or perhaps a M&P 15-22? The ballistics you're describing also fit .22lr.

 

[rtquig]

Let me get this straight.....

Groups are ok 2-3in.
No keyhole.
40yd zero = 8in low at 100yd
100yd zero = 3ft low at 200yd.

If all this is correct, this is the ballistics of a 62gr bullet with a muzzle velocity of around 900fps instead of typical 5.56 of 3000fps. Which begs the question... again... is the gun cycling or are you having to charge each round?

Are you actually shooting an M&P 15? Or perhaps a M&P 15-22? The ballistics you're describing also fit .22lr.

Phil,
After re-reading his posts, he is using 55 and 62 grain, so its got to be a Sport as he first stated.
For a second, I thought you had the answer. I guess we will have to see what S&W discover.

 

[rodney winston]

ive shot 55 and 62 grain tula and first time initial sight in. when i got to 100 yard re sight in shot a box of pmc bronze 55 grain to try to get groups they were pushin 3 inch but no keyhole that was visible. after seeing how low it was at 200 i pulled that much hold over on a 225yard 2x3 steel plate the pings sounded same as normal ar 15 round strikes.that is why im seeing af anybody knows if a bullet can fly slightly canted down making aerodynamics off because only gravity and wind make bullets alter from thier origional straight line from barrel thus slight down angle the air would make bullet drop faster than the normal and loose velocity faster.hope when i get rifle back they can explain it to me instead of just saying they replaced barrel or reciever because this seems impossible.this fact i agree with everybody

 

[Newhouse]

Did you try other brands of ammo besides pmc and tula or at least from different lot?
Also did you remove the flash hider to inspect the condition of the crown?
Anyway, intersted to hear what S&W have done to your rifle when you get back.

 

[C J]

With even just 2 types of ammo it doesn't seem likely the problem is ammo related. The chances of two different types of ammo being off that much are pretty slim IMO. I don't think it's a scope mounting issue either. That's just too much of a difference at 100 yards compared to 40 yards. The OP has shot other firearms and apparently has enough knowledge to get those to work right. So user error doesn't seem very likely to me. If the rifle is hitting at 40 yards and 10" low at 100 yards there's something fishy going on IMO.

I'd have to guess that it's a barrel issue. And that's not good. Problems happen with all gun makers. My Sport is right on the money from 40 yards to 140 yards using the irons. Line of sight issues are the same with iron sights as they are with scopes. It could just be the bore was drilled badly. But I really wonder about that too since a badly drilled bore should cause erratic shooting in more ways than described.

Without being there to check out the rifle myself I can't hazard a guess that fits all the conditions. Sending the rifle back to S&W was the right idea IMO. You'll find out for sure if there's a problem. Just make sure they actually test the rifle while they have it. Sometimes companies will fire at a certain distance and if things are right there they send your rifle back saying it's OK. I've had that happen to me on a rifle that was keyholing badly. Apparently my problem was a nub in the crown because it stopped shooting keyholes all of a sudden like it never happened. I was about to send it back a second time when it started shooting right. It shoots great now. It must have knocked down a num with enough bullets hitting it to do the job.

You could have an issue like that. A barrel issue of some kind just seems likely to me.

 

[REM 3200]

Just to satisfy my poor old brain, where did the 40 yard zero come from? A 50 yard zero as the bullet is on it's way up will give a zero of just a little over 200 yards with a 5.56mm 55 gr. bullet. I don't think I have ever seen anyone zero at 40 yds. before. Just curious.

 

[Rastoff]

Just to satisfy my poor old brain, where did the 40 yard zero come from?

This was my question too. Then I remembered that many like to use 36 meters (39.4 yards) to zero their gun. Using this zero will give a decent hit range from very close all the way out to 300 meters.

I don't like this because the POI at 100 yards would be higher than I'd like. Still, it is a common zero distance these days.

 

[uncledoggle]

At one time there was a very good video on Youtube, since removed, that gave a excellent arguement for a 36 yd. zero. Short version: All hits between 25 and 300 yds. would be in the vitals. And at 400 yds. the bad guy becomes a soprano.

 

[Kadonny]

At one time there was a very good video on Youtube, since removed, that gave a excellent arguement for a 36 yd. zero. Short version: All hits between 25 and 300 yds. would be in the vitals. And at 400 yds. the bad guy becomes a soprano.

That's actually a great thought for a battle rifle. It's not about punching holes in a bullseye, it's about body mass hits and thoughtless aiming.

 

[rodney winston]

im normaly shooting hunting rifles with medium mounts scope 1 and 1/4 to 1 and 1/2 inch above barrel -center of scope to center of barrel- i use 25 yards for this. because of taller mounts just moved out a lil thought it would be closer to 100 yard 1 to 2 inch high. my main goal is to get on paper at 200 yards so i can get 200 yard zero so i can hit coyote size game from 10 to 300 yards with out too much guess work.

 

[mbliss57]

This is a very interesting problem..I am really hoping S&W gives an explanation of the problem not just a replaced barrel or something like that and noting explaining the issue. Please keep us posted when you hear from S&W. I have also learned something about a 40 yard zero. Something new to me..but it does make sense for hunting.

 

[Rastoff]

This is a very interesting problem..I am really hoping S&W gives an explanation of the problem not just a replaced barrel or something like that...

They won't. In fact, they'll most likely just replace the barrel without doing any troubleshooting.