S&W MP10 Accuracy trouble

[JDC215]

I have had a Smith and wesson mp10 with the 18" 1:10 twist 5R barrel for a few years now. aside from putting a 4-12 leupold VX2 CDS scope on it and a magpul moe fixed carbine stock i really haven't done anything to it. for all intents and purposes its in stock form.

ive never been able to get a group tighter than 1.5" @ 100 yds. Ive tried Hornady interlock 150, 165 and 180, speer BTSP 180, Hornady ELDX 178 and i think i tried some Hornady 165 SST that i have in my crate of .308 bullets and nothing seems to work tighten that up. ive shot these bullets mostly with varget and cfe223 but this last ladder I switched to Ramshot Big game and i wasnt real excied about 2" groups. some times i wonder if its just me but then i have a relitively lightweight .223 rifle that i can shoot 3/4" groups with.

my goal is to be able to consistently hit a 1/2 d28 at 500 yds preferably with a bullet that would still be able to perform on a deer at those ranges.

all of my loads have been at the upper end of the load data. im begining to wonder if this semiautomatic action would be a bit happier with something closer to the middle of the spectrum, but that's just a guess. i also spoke to a local long range competitor who recommended the sierra 17t5 SMK. as many of you are aware reloading components are real hard to come by at the moment but i do have some varget, cfe 223 and biggame as well as a few hundred primers Remington, cci and Winchester and i would prefer to stick to a relatively economical bullet because i would like to shoot a lot of them over the next several years!

i hope I'm not too long winded but I am trying to be specific and provide plenty of information and thank you in advance for any help.

 

[Tortuga]

Have you tried replacing the trigger?

A funny thing I've noticed is that a lot of shooters don't actually know how pull a trigger. I sincerely feel my ability to get 2 MOA out of my SKS with steel ammo is simply because of my control on the trigger (I have pics to prove it!).

Not saying that's you, but working on trigger pull or even replacing a trigger can do wonders for accuracy.

 

[gotboostvr]

Normally, I'd suggest running a box of both 168gr and 175gr Federal Gold Medal Match through it and see if it shoots well with that. If it does, more load development is in order, if it dosen't, something on the gun itself needs addressed. But things being the way they are with ammo availability not sure of that's in the cards.

 

[JDC215]

Have you tried replacing the trigger?

A funny thing I've noticed is that a lot of shooters don't actually know how pull a trigger. I sincerely feel my ability to get 2 MOA out of my SKS with steel ammo is simply because of my control on the trigger (I have pics to prove it!).

Not saying that's you, but working on trigger pull or even replacing a trigger can do wonders for accuracy.

i have replaced the trigger with a velocity 3.5 lb drop in trigger. im a pretty good pistol shooter andive done hours upon hours of dryfiring with those but im not srue that translates over 100%

 

[Thomasss]

4064 is an excellent powder for your rifle. Can you give any more information on primers and bullet seating depth? Have you ever measured the throat of your gun?

 

[JDC215]

if i come across any 4064 ill be sure to pick it up. ive been shooting remington large rifle non-magnum primers and my seating deapths are around the max length i can manage and still fit into an SR25 pattern magazine. i normally leave the tips 10 to 20 thousandths fron the front of the mag.

the last two loads i tried were 5 shot groups of speer 180 spbt over 49 and 50 grains of ramshot biggame, remington large rifle primers, seated to 2.80 which barely fit the mag but did not drag. cartridges were trimmed to length before the previous loading.

 

[army_eod]

That is probably expected groupings with that piece.

 

[FL-NC]

1 MOA or less with any AR10 can be difficult/pricey to come by- even with a good trigger, scope, ammo, and properly applying the basics. I can do it with my Larue OBR with Horus Falcon 5-20x and M118 LR. I also have a slight advantage over some people due to lots of practice- but there is a whole lot of $ in that rifle setup. And I can't do it with my DPMS AR10 carbine with a Larue trigger and an identical scope and the same ammo- we're looking at 1- 2 MOA, so....

 

[mshootnit]

I have had a Smith and wesson mp10 with the 18" 1:10 twist 5R barrel for a few years now. aside from putting a 4-12 leupold VX2 CDS scope on it and a magpul moe fixed carbine stock i really haven't done anything to it. for all intents and purposes its in stock form.

ive never been able to get a group tighter than 1.5" @ 100 yds. Ive tried Hornady interlock 150, 165 and 180, speer BTSP 180, Hornady ELDX 178 and i think i tried some Hornady 165 SST that i have in my crate of .308 bullets and nothing seems to work tighten that up. ive shot these bullets mostly with varget and cfe223 but this last ladder I switched to Ramshot Big game and i wasnt real excied about 2" groups. some times i wonder if its just me but then i have a relitively lightweight .223 rifle that i can shoot 3/4" groups with.

my goal is to be able to consistently hit a 1/2 d28 at 500 yds preferably with a bullet that would still be able to perform on a deer at those ranges.

all of my loads have been at the upper end of the load data. im begining to wonder if this semiautomatic action would be a bit happier with something closer to the middle of the spectrum, but that's just a guess. i also spoke to a local long range competitor who recommended the sierra 17t5 SMK. as many of you are aware reloading components are real hard to come by at the moment but i do have some varget, cfe 223 and biggame as well as a few hundred primers Remington, cci and Winchester and i would prefer to stick to a relatively economical bullet because i would like to shoot a lot of them over the next several years!

i hope I'm not too long winded but I am trying to be specific and provide plenty of information and thank you in advance for any help.

I have had a couple MP 10 rifles that were very accurate. Sub 2.5" groups at 200 yds for 3-4 shots were routine. One liked pretty much any 150 gr. SST load and the other , for some weird reason, loves PMC XTAC Match ammo.
I think I was also using a crimp on the cannelure. I think that helped.
You are resting the forend on a bag (not the barrel) and no sling pressure, right?
An MP10 with a trigger upgrade should do 4 shots under 1.5" at 100 yds.

 

[C-grunt]

Is this a rifle with a free floated barrel?

In reality, 1.5 MOA with a run of the mil AR10 is decent shooting.

Also if you are used to precision rifle shooting with a bolt gun you need to really focus on follow through with the AR10. The lock time is longer on an AR than with a bolt gun.

 

[Thomasss]

Have you ever tried something less than maximum length when seating bullets. There are several sweet spots in reloading without going to maximum length and I have never found maximum length to be that great. Look at Hornady's recommended seating length for a given size bullet, then extended the bullet out by another .040 and shoot a few to see how they group. I found this to better a good starting point. It is also a safe starting point so one doesn't have to worry about cartridges coming apart in the chamber or bullets getting stuck in the rifling, etc.

 

[JDC215]

Is this a rifle with a free floated barrel?

In reality, 1.5 MOA with a run of the mil AR10 is decent shooting.

Also if you are used to precision rifle shooting with a bolt gun you need to really focus on follow through with the AR10. The lock time is longer on an AR than with a bolt gun.

No it is not. I do understand that that should improve accuracy, but have you any ides how much it might actually improve accuracy? I realize every gun is an individual but im just looking for some ball park numbers.

 

[The Glockodile]

IMR 3031, 4064, 8208 XBR, Hodgdon Varget with 168 / 175 / 177 / 185 grain bullets are usually a good combo...

 

[C-grunt]

No it is not. I do understand that that should improve accuracy, but have you any ides how much it might actually improve accuracy? I realize every gun is an individual but im just looking for some ball park numbers.

I definitely wouldn't be surprised if your rifle dropped closer to or at 1 MOA when free floated. But like you said every rifle is different. Really accurate AR10s are not easy to build. That's why the ones that are known for good accuracy all cost a few thousand dollars.

 

[bfoosh006]

Free floating the barrel will he

No it is not. I do understand that that should improve accuracy, but have you any ides how much it might actually improve accuracy? I realize every gun is an individual but im just looking for some ball park numbers.

Free Floating the barrel will help with consistency for sure. It is very hard to attach a ball park figure to the improvement possible. Basically to many variables involved.
You do want the firearm's moving parts to return to the same position as much as possible.
So taking any pressure off of the barrel ( Free floating it ) will help eliminate that variable.

I would suggest a thorough barrel cleaning. Some of my best groups have ( grudgingly ) been fired from a clean barrel.
Triple check your scope is tightly mounted and in good condition. ( I had a scope that wore out and would start to throw fliers after about 15rds )

Try some Fed. Gold Medal Match 168gr... shoot the whole box of 20, in 5rd groups. IMHO , consider the first 5rds as throw away.
How are you shooting ? Off a bench I assume, but are you using a front bag ? Rear squeeze bag ? I shoot better off of a pair of bags then I do off of a bipod.

And , IMHO, firing a Large Frame AR , off the bench, requires a whole different approach then any other rifle.
I tend to hold the trigger back , way after the discharge, don't fidget in the slightest at the bench, lock your body one position, and don't move anything until you have fired your group. I don't care if my group is off my POA... I just stay focused on that one spot. And frankly, I don't want to shoot out my targets POA.

Make sure you put the cross hairs on a repeatable POA... I use the top, 12 o'clock position, of whatever dot I am aiming at.
Given your recticle , I would try to use a corner POA on the crosshairs while shooting for accuracy. ( If possible, I don't know how old your eyes are )

Is the rest of the M&P10 in stock form ? How is the recoil impulse ? Are the fired brass rims abused after firing ?
A heavier buffer and recoil spring might help slow the cyclic speed slightly.

 

[mshootnit]

Mine likes 150 gr. SST with a crimp on the cannelure. I forget the powder charge but I am thinking Hodgdon 4895, or IMR4895

 

[JDC215]

Free floating the barrel will he


Free Floating the barrel will help with consistency for sure. It is very hard to attach a ball park figure to the improvement possible. Basically to many variables involved.
You do want the firearm's moving parts to return to the same position as much as possible.
So taking any pressure off of the barrel ( Free floating it ) will help eliminate that variable.

I would suggest a thorough barrel cleaning. Some of my best groups have ( grudgingly ) been fired from a clean barrel.
Triple check your scope is tightly mounted and in good condition. ( I had a scope that wore out and would start to throw fliers after about 15rds )

Try some Fed. Gold Medal Match 168gr... shoot the whole box of 20, in 5rd groups. IMHO , consider the first 5rds as throw away.
How are you shooting ? Off a bench I assume, but are you using a front bag ? Rear squeeze bag ? I shoot better off of a pair of bags then I do off of a bipod.

And , IMHO, firing a Large Frame AR , off the bench, requires a whole different approach then any other rifle.
I tend to hold the trigger back , way after the discharge, don't fidget in the slightest at the bench, lock your body one position, and don't move anything until you have fired your group. I don't care if my group is off my POA... I just stay focused on that one spot. And frankly, I don't want to shoot out my targets POA.

Make sure you put the cross hairs on a repeatable POA... I use the top, 12 o'clock position, of whatever dot I am aiming at.
Given your recticle , I would try to use a corner POA on the crosshairs while shooting for accuracy. ( If possible, I don't know how old your eyes are )

Is the rest of the M&P10 in stock form ? How is the recoil impulse ? Are the fired brass rims abused after firing ?
A heavier buffer and recoil spring might help slow the cyclic speed slightly.

lots of questions here, but ill answer what i can.

I have been shooting off of a concrete bench with sand bags stacked in front and a small bag in the rear and the seat as low as i can comfortably go. I like the idea of shooting at the corner of a square or 12:00 on a circle that may be helpful. The rest of the gun is stock. I dont think the scope is the issue, its a Leupold VX-2 4-12x40 cds. its not the most expensive but its not a wal-mart special either. im not sure about the recoil impulse, it seems like i could be a bit softer for a .308 but i have not shot too many ar-10s so i dont have much to compare it to. with the heavier loads the brass has come out fairly abused. I wonder if that might be the biggest issue, maybe the cycling needs to be slowed down a bit.

 

[d2wing]

Many things can affect accuracy. Is the bolt and BCG operating smoothly? I had a PSA that the bolt and BCG were binding slightly. It wouldn't shoot until I replaced both. Does everything fir correctly. Maybe you need to take it apart and upgrade parts. Most of my most accurate loads were under maximum.