New AR/Fighting with 77grn SMKs

[jlamb]

All, I just had a new AR built. It will shoot one .250" group and the next will be 1" then back to .250. Most of the 1" groups are 2 good shots + one flyer. I thought is was me but I can shoot .25" groups all day with my varmiter and the AR's "inconsistancy" is too consistant...

The rifle-
20" Yankee Hill w/1 in 7" twist
VLTOR Upper
New Frontier Lower (fitted to upper)
Leupold MK AR 6-18 Mil dot scope

COAL touching lands is 2.410" giving a .150" jump when loaded to 2.260".

I've tried the following loads:

77SMK w/CFE223;
21.5
22.0
22.5
23.0
23.5

77SMK w/H4895;
21.5
22.0
22.5
23.0
23.5

77SMK w/H335;
21.0
21.4
21.8
22.2
22.6

77SMK w/TAC;
22.0
22.7
23.4
24.1
24.8

I have also tried Nosler Custom Competition 77 grs;

77grn Nos CC w/CFE223;
22.5
23.0
23.5
24.0
24.3

77grn Nos CC w/Varget;
21.5
22.0
22.5
23.0
23.5

This one is a head scratcher. Any tricks to improve consistancy appreciated. I can post pics of targets later.

J

 

[Graham]

Re: New AR/Fighting with 77grn SMKs

Is your 'flyer' always on the last shot?

 

[kraigWY]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> 2 good shots + one flyer</div></div>


I don't see how a "true" group can be determined with 3 shots.

Try 10 shots and see what groups you get.

 

[Graham]

Re: New AR/Fighting with 77grn SMKs

Better yet, shoot some strings of five dots.

 

[Outsydlooknin75]

Re: New AR/Fighting with 77grn SMKs

I'm betting the flyer is the first round out of the mag .......

 

[Beef82]

Re: New AR/Fighting with 77grn SMKs

While I generally have no problem with three shot groups if the results are proving inconsistent there is a good change its being caused by a lack of data points. If the same shot number is always the flyer this may not be the case however. Also does the rifle have the same trigger, optic height, and furniture as your varminter? If not the comparison is not neccesarily valid.

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

First off I would just stick 24gr of Re15 behind the 77s at 2.28" and don't try anything else, if it doesn't shoot with that load something is wrong.
On trigger control with a AR you must hold the trigger back until the bullet hits the target. Do not allow the trigger to reset while the bullet is in the bore. An ARs lock time is much slower than a bolt gun.
driving a light AR is different than a bolt gun. Watch the front end,if you get a lot of muzzle rise you may need to use a little more front end control so the muzzle isn't coming up while the bullet is in the bore. Watch Tubbs use a sling.

 

[Graham]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">On trigger control with a AR you must hold the trigger back until the bullet hits the target. </div></div>What if the bullet misses the target?

Can you clear-up when I can let go of the trigger, and why?

 

[TonyAngel]

Re: New AR/Fighting with 77grn SMKs

As mentioned, try some Reloader 15 or Varget with those 77s.

With those OALs, I'll assume that you are single loading using a sled, right?

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">On trigger control with a AR you must hold the trigger back until the bullet hits the target. </div></div>What if the bullet misses the target?

Can you clear-up when I can let go of the trigger, and why? </div></div>
If you allow the trigger to reset or any movement of your finger or anything else while the bullet is in the bore it will hurt accuracy. AR triggers have a very slow locktime compared to a Rem 700. Trigger follow through is important with any firearm.
If you wait til the bullet contacts you know it's not in the bore.

 

[seanhagerty]

Re: New AR/Fighting with 77grn SMKs

I would try 24gr of Varget with those 77 SMK's loaded to mag length. Get that load over some Rem 7 1/2 primers and go to town. I found I could shoot 1/4" groups with any brass I gave it.

 

[Graham]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">If you allow the trigger to reset or any movement of your finger or anything else while the bullet is in the bore it will hurt accuracy. AR triggers have a very slow locktime compared to a Rem 700. </div></div>It makes sense that if the rifle moves when the bullet is in the bore the POI will deviate from what the POA was when the rifle was fired.

But...

AR Trigger lock time: 16 Ms.
Bullet in bore: 1.24 Ms.
Can you perform a trigger reset within 18 milliseconds?

My thinking is that there's more to it with regard to why one holds the trigger back on an AR.

Because the rifle moves anyway:
http://www.the-long-family.com/OBT_paper.htm

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

Thanks everybody, all great advice.

Bustin - I'll try RL-15 and see were it get's me. What primer are you using? I've been loading everything with CC1 BR-4's.

Per the flyer - It's pretty random. I'll move to 5 and 10 shot groups next.

I should also have noted that I can very consistantly shoot .75" groups all day with an off the shelf Bushmaster A2 w/a 4 x scope. My point was to say that can tell when I pull and I'll be the first to admid it. No use blaming the rifle or load if I want to be a better shooter.

See my groups below -

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlamb</div><div class="ubbcode-body">Thanks everybody, all great advice.

Bustin - I'll try RL-15 and see were it get's me. What primer are you using? I've been loading everything with CC1 BR-4's.

Per the flyer - It's pretty random. I'll move to 5 and 10 shot groups next.

I should also have noted that I can very consistantly shoot .75" groups all day with an off the shelf Bushmaster A2 w/a 4 x scope. My point was to say that can tell when I pull and I'll be the first to admid it. No use blaming the rifle or load if I want to be a better shooter.

See my groups below -

</div></div>
CCI 450s or 41s usually.
Nothing wrong with BR4s I just like the hotter spark of the 450s, produces apx 40-50 fps more.

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">If you allow the trigger to reset or any movement of your finger or anything else while the bullet is in the bore it will hurt accuracy. AR triggers have a very slow locktime compared to a Rem 700. </div></div>It makes sense that if the rifle moves when the bullet is in the bore the POI will deviate from what the POA was when the rifle was fired.

But...

AR Trigger lock time: 16 Ms.
Bullet in bore: 1.24 Ms.
Can you perform a trigger reset within 18 milliseconds?

My thinking is that there's more to it with regard to why one holds the trigger back on an AR.

Because the rifle moves anyway:
http://www.the-long-family.com/OBT_paper.htm </div></div>
You can shoot how ever you want, it's not going to effect my shooting.

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

Per the trigger, I definetly focus on a slow squeeze, pull straight back into the trigger and keep it held for quite some time after the shot. On my AR's of usually let it out when I reset to the target (3 to 4 seconds).

 

[Temp9]

Re: New AR/Fighting with 77grn SMKs

Holding the trigger back helps with follow-through. You can't reset the trigger in 18ms, but you can vary the pressure and direction of your trigger squeeze in the milliseconds before the shot and during lock time. I used to have a nasty flinch when shooting handguns. Most people, me included, couldn't see the muzzle dip right before the shot, but I would hit 2 feet low at 15 yards. Point is, your brain can anticipate the moment right before the shot with extreme accuracy. If you bounce off the trigger, you will often start the decrease pressure on the trigger before it breaks, not after. And as such, you can pull the shot and the recoil will cover up the movement.

By the way, I've shot .25" 3 shot groups with 55gr Wolf. My usual groups look more like 7-8". Ditch the 3 shot group thing, IMO.

 

[Graham]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">You can shoot how ever you want, it's not going to effect my shooting. </div></div>Any thoughts on how an AR recoils and the moving mass inside the rifle?

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Temp9</div><div class="ubbcode-body">Holding the trigger back helps with follow-through. You can't reset the trigger in 18ms, but you can vary the pressure and direction of your trigger squeeze in the milliseconds before the shot and during lock time. I used to have a nasty flinch when shooting handguns. Most people, me included, couldn't see the muzzle dip right before the shot, but I would hit 2 feet low at 15 yards. Point is, your brain can anticipate the moment right before the shot with extreme accuracy. If you bounce off the trigger, you will often start the decrease pressure on the trigger before it breaks, not after. And as such, you can pull the shot and the recoil will cover up the movement.

I'll be trying 5 shot groups until I narrow down a load. More info next week.

By the way, I've shot .25" 3 shot groups with 55gr Wolf. My usual groups look more like 7-8". Ditch the 3 shot group thing, IMO. </div></div>

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">You can shoot how ever you want, it's not going to effect my shooting. </div></div>Any thoughts on how an AR recoils and the moving mass inside the rifle? </div></div>
If your carrier is moving while the bullet is in the bore you have an over-gassed rifle.

 

[Graham]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">You can shoot how ever you want, it's not going to effect my shooting. </div></div>Any thoughts on how an AR recoils and the moving mass inside the rifle? </div></div>If your carrier is moving while the bullet is in the bore you have an over-gassed rifle. </div></div>http://www.snipershide.com/forum/ubbthre...808#Post2846808

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

That's what I mean there is no moving mass while the bullet is in the bore. After the bullet exits the carrier moving, flinching, jerking or letting the trigger reset does not matter.
Light weight ARs can recoil or have more muzzle rise than a heavier bolt gun or heavier barrel AR. Some require more front end control to get better accuracy from them especially with some of the other calibers like the 6.8 and 6.5.

 

[InfiniteGrim]

Re: New AR/Fighting with 77grn SMKs

77gr loaded to 2.255" COAL
24.0gr Varget
CCI 41
brass was trimmed, and had the flashhole deburred.

I pulled the last shot, including the 10th shot it would still be .7moa

 

[gnhowell1]

Re: New AR/Fighting with 77grn SMKs

Try some 75 gr Hornady hpbt's. They seem to work a little better than the 77's for me.

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

from 6mmBR.com's 223 page.I've been using the Re15 load for 69s and 77s for close to 15 years.

VV N540 26.2 CCI 400 69 Lapua Scenar 3179 fps Vihtavuori's MAX load for BOLT GUN. Start at 24.2.
AA 2520 26.0 Rem 7.5 69 Sierra MK 3000 fps AR-friendly load. Very Accurate. Watch for powder lot variations though.
H4895 24.5 Rem 7.5 75 JLK VLD 2905 fps Hodgdon MAX load for BOLT GUN. Too hot for AR15.
Reloader
15 24.1 Rem 7.5 77 Sierra MK 2600 fps Close to a "standard" load for AR15 long range matches. You can substitute 23.9 Varget.
VV N140 23.5 Rem 7.5 80 Sierra MK 2550 fps Sierra MAX "Accuracy Load" for AR15s. RL15 is good for 2600+

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

InfiniteGrim - nice group. That's what I'm hoping for!

Bustin - getting some RL15 tomorrow. I'll let you know how it goes.

 

[Sowastrong Industries]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">from 6mmBR.com's 223 page.I've been using the Re15 load for 69s and 77s for close to 15 years.

VV N540 26.2 CCI 400 69 Lapua Scenar 3179 fps Vihtavuori's MAX load for BOLT GUN. Start at 24.2.
AA 2520 26.0 Rem 7.5 69 Sierra MK 3000 fps AR-friendly load. Very Accurate. Watch for powder lot variations though.
H4895 24.5 Rem 7.5 75 JLK VLD 2905 fps Hodgdon MAX load for BOLT GUN. Too hot for AR15.
Reloader
15 24.1 Rem 7.5 77 Sierra MK 2600 fps Close to a "standard" load for AR15 long range matches. You can substitute 23.9 Varget.
VV N140 23.5 Rem 7.5 80 Sierra MK 2550 fps Sierra MAX "Accuracy Load" for AR15s. RL15 is good for 2600+
</div></div>
Bustin,
I'm curious why you mentioned the H4895 load was too hot for AR-15. A 5.56 chamber rated to higher pressure than .223?

Matt

 

[USACS]

Re: New AR/Fighting with 77grn SMKs

I load 2.260" to fit in a magazine with 24.1gr of RL15, and I'm pulling .460 MOA. As has been stated, reduce your load COAL and see what it gets you.

 

[InfiniteGrim]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gnhowell1</div><div class="ubbcode-body">Try some 75 gr Hornady hpbt's. They seem to work a little better than the 77's for me. </div></div>

What kind of accuracy you getting with them. I personally have had problems with horrible consistency. I have shot .4moa 5 shot groups, but then the next will be 1.5-2moa.

 

[redirt78]

Re: New AR/Fighting with 77grn SMKs

Posting to watch this thread

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: msowa</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">from 6mmBR.com's 223 page.I've been using the Re15 load for 69s and 77s for close to 15 years.

VV N540 26.2 CCI 400 69 Lapua Scenar 3179 fps Vihtavuori's MAX load for BOLT GUN. Start at 24.2.
AA 2520 26.0 Rem 7.5 69 Sierra MK 3000 fps AR-friendly load. Very Accurate. Watch for powder lot variations though.
H4895 24.5 Rem 7.5 75 JLK VLD 2905 fps Hodgdon MAX load for BOLT GUN. Too hot for AR15.
Reloader
15 24.1 Rem 7.5 77 Sierra MK 2600 fps Close to a "standard" load for AR15 long range matches. You can substitute 23.9 Varget.
VV N140 23.5 Rem 7.5 80 Sierra MK 2550 fps Sierra MAX "Accuracy Load" for AR15s. RL15 is good for 2600+
</div></div>
Bustin,
I'm curious why you mentioned the H4895 load was too hot for AR-15. A 5.56 chamber rated to higher pressure than .223?

Matt </div></div>
That is a copy and pasted chart on 6mmBR.com
The notes were made by the competitors using that load so I would say that guy's custom competition bolt gun has a Wylde or similar chamber.
6mmbr.com -.223 page
That load of Re15 is used by a lot of highpower shooters, some use Varget but RE15 will usually produce more velocity.
I have never seen a barrel that was in spec (7- 8 twist only)not shoot that load well.
If a barrel will not shoot light short bullets well try 69s or 77s. 1/2-28 thread can make the muzzle swell and let the bullets wobble as they exit the muzzle. If you can insert a .219 inspection pin in the muzzle but it stops apx 3/4" in then the muzzle is swelled due to relieving too much metal to cut the 1/2-28 threads. The 69 and 77 Sierras have a longer body and are a true .224 bullet so they will shoot better out of a barrel that has a swelled muzzle.

 

[65nut]

Re: New AR/Fighting with 77grn SMKs

Tag

 

[Sowastrong Industries]

Re: New AR/Fighting with 77grn SMKs

I understand now, thank you for explaining Bustin. .223 wylde chambered AR, understood. Matt

To the OP, apologies for the interjection. Personally I like
Nosler 69gr hpbt
25.5gr H4895
Mixed brass
CCI 41
Trimmed with Lee .223 trimmer
2.260-mag length

I've got some 77's been wanting to try but haven't seen any reason to change.

 

[BCP]

Re: New AR/Fighting with 77grn SMKs

Infinite, the 75 hornadys group well but are picky about seating depth. They didn't start grouping for me until I seated them deeper usually 2.245 COAL. Plus side is they feed great from all my mags.

 

[Greg Langelius *]

Re: New AR/Fighting with 77grn SMKs

Load a single magazine to full capacity, and shoot groups of 5 with that magazine until you're 'E' several times. If the flyer corresponds to the first or last cartridge in the magazine, try the same with each of your other magazines.

Flyers that correspond to a cartridge's position in the magazine (except maybe the first cartridge on top) are almost always an indication of a magazine related issue.

When the flyer is the first one, and/or is related to a full/not full magazine difference, the issue could be a magazine, or it could be related to bolt lubrication and/or buffer spring functioning.

Often a new magazine will 'wear in', and that can be helped by polishing off any excess finish roughness from the inside/underside of the magazine lipe with fine steel wool or sandpaper.

The buffer spring may benefit from a light application of grease. I use automotive 'White Spray Grease' sparingly on the buffer/spring, and on the bolt carrier and T-handle's underside. A little grease can eliminate that weird Matty Mattel 'Boing' which often accompanies the AR's cycling sound heard through the hearing protection.

Sometimes it can be as simple as changing from loading with an open bolt and releasing the bolt, to loading with a closed bolt and pulling the charging handle fully rearward and releasing it. Try both. I use the bolt assist knob pretty regularly.

Greg

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

Greg,

Thanks for the advice. I'll try it all. I hope to have this AR issue solved this weekend.

 

[Joel45]

Re: New AR/Fighting with 77grn SMKs

Reading this with interest. I am fighting the very same thing. I had a Douglas barrel turned by CLE and it will not shoot 77 grain SMKs. Can't get decent groups with 60 grain v-max's either. I have tried the barrel in a Vltor monolithic upper, as well as a Larue upper / DD rail with no luck. I have swapped bolts, carriers and anything I can think of to eliminate an equipment problem. I did, however, have CLE cut the chamber for my bolt.

One interesting fact worth mentioning is that when I install my Ops Inc 12th model can, I get a full mil of poi shift. I have never had more than an inch of poi shift with either of my Ops Inc cans on any of my rifles. I have tried three different Ops breaks thinking I had a non-concentric brake. No luck. I eventually pulled the brake off completely to eliminate that variable.

I am going to give it one more run and then it is...back to CLE to see if they can shed some light on this...or the garbage. I have spent way too much ammo and time on this thing. Ain't fun no more.

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Joel45</div><div class="ubbcode-body">Reading this with interest. I am fighting the very same thing. I had a Douglas barrel turned by CLE and it will not shoot 77 grain SMKs. Can't get decent groups with 60 grain v-max's either. I have tried the barrel in a Vltor monolithic upper, as well as a Larue upper / DD rail with no luck. I have swapped bolts, carriers and anything I can think of to eliminate an equipment problem. I did, however, have CLE cut the chamber for my bolt.

One interesting fact worth mentioning is that when I install my Ops Inc 12th model can, I get a full mil of poi shift. I have never had more than an inch of poi shift with either of my Ops Inc cans on any of my rifles. I have tried three different Ops breaks thinking I had a non-concentric brake. No luck. I eventually pulled the brake off completely to eliminate that variable.

I am going to give it one more run and then it is...back to CLE to see if they can shed some light on this...or the garbage. I have spent way too much ammo and time on this thing. Ain't fun no more. </div></div>
If the barrel shoots other bullets well there is nothing wrong with the barrel. If it was a bad crown or chamber then the other bullets wouldn't shoot well either.

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

Joel,

I have seen many cans shift the POI on very precision made rifles. If you're altering the "turbulance" caused by the gases after the bullet leaves the barrel it stands to reason that the POI could change. I guess the question is "After the POI shift, is the grouping still consistant?"

I'm going to step up to 5 shot groups today and verify if my flyers are a magazine issue. I don't think that this is the case because I hand fed the cartridges and found the same issue.

One the I did find was that the 77SMK has a .150" jump to the lands. This is great if you want your rifle to work with any type of ammo but really bad if you want to set it up for one caliber. After owning several custom bolt actions, I'm wondering if I need to get a custom chanmbered barrel made what will give me .020" jump at magazine length load.

 

[bustin]

Re: New AR/Fighting with 77grn SMKs

I can load out to 2.28 in a metal mag.
PRI 6.8 mags allow 2.295, if they make 556 mags they may help.

 

[ssatt68]

Re: New AR/Fighting with 77grn SMKs

Jlamb,
What trigger do you have in the lower? Triggers and barrels are the heart and soul of the AR. You could have the best barrel on the planet and if you are running a box stock mil-spec trigger your results will vary. JP rifles, Timney and Geissele make outstanding triggers. I hope I am not beating a dead horse but trigger pull and reset are enormous for proper follow through. The AR platform demands impeccable fundamentals; a bolt gun is far more forgiving. Next time you head to the range dry fire a bunch before you settle in to shoot your next string and look for a barely noticeable jump in your sight picture. If this occurs you’ll need to grip the weapon with a firmer hand. Looking at your groups it is possible that you are pushing the trigger slightly from right to left. There are many different ways to mount the trigger some guys like to use the pad of their firing finger, some guys like to mount the trigger in the crease of their first knuckle, and both have merits. I try to visualize the trigger extending from the bore all the way to butt stock and squeeze the trigger down the imaginary line formed. Additionally, anything ¾ or better out of a gas gun is great.
I went from a box stock Rock River trigger set up in my HP rig to a Geissele and added 22 points to my avaerage HP score overnight. Guys with JP LRP-07s and GAP 10s shoot sub .5 moa groups all the time and it has a lot to do with the trigger set up. Crisp single stage triggers. Just my 2 cents and I hope this helps.

 

[sic65stang]

Re: New AR/Fighting with 77grn SMKs

I think the others are right about follow through with the trigger, removing my finger from the trigger is the last component of a shot for me. I think if you are getting random flyers maybe you should check your scope tightness? It may just be moving a bit every once in a while? Also, why not move to a little lighter bullet, 69 GN? Shot this today with 69 SMK, 25gn Varget, loaded to mag legnth. Thats the combo best for me, try it out.

*EDIT* The flyer was called. Unfortunately it was a 5 shot group so I guess I have to count it. lol.

 

[Greg Langelius *]

Re: New AR/Fighting with 77grn SMKs

Shooting my AR off a bipod/bench (with rear bag) yesterday, I noticed some small but clear crosshair jump whan the rifle firing adjacent to my bench would go off. My bench is wood, but it's also rather sturdily constructed and exhibits neither wobble nor rock. The most likely conclusion I can draw is that I'm doing something subliminal to make this happen; and I'll be danged if I can figure out how to manage this matter.

The symptoms appeared as horizontal strings at several well defined and relatively close levels across the bull. While it was all in there at the 2MOA level at 250yd, it still made a mockery of my score.

When shooting from a rest with my bolt gun under identical conditions during alternating relays, this issue did not arise. I'm guessing there might be some contribution to this coming from the bipod, but again, as to how and why, I'm clueless. I intend to apply my sling and bipod technique to see if there's some help to be found there.

I take heed to the representations above about how the AR is unforgiving. While there is probably still some load development refinement called for, and it is undergoing; I will be primarily concentrating on technique and consistency. My best guess is that it's me, and not the gun, that is at the root of all this. It's a new gun and I'm still learning about how it prefers to be shot.

The scope is utterly solid. It's a Weaver T-24 with Weaver dual top strap see-thru rings mounts directly to the flattop and really solidly tightened. The mount system is as simple, direct, and rugged as I can visualize at the current moment. Optical axis height is not lavish, but I can get a decent cheekweld on the A2 stock without any image shadowing.

I also suspect may still be a cheek weld issue despite my confidence otherwise, and I'm going to try something from left field, based on a ,to see if that helps.

Greg

 

[eracer]

Re: New AR/Fighting with 77grn SMKs

I believe that POI shift with a suppressor is far more due to the added weight at the end of the barrel affecting harmonic vibration than the effect of muzzle gas perturbations.

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

Well took the AR up yesterday and tried 10 different load with 2 different powders. I've settled on 77SMK w/24grains of CFE223. I shot 5 round groups vs the 3 I was shooting before. There was no correlation between flyers and magazine/load positio.

One thing I noticed is that most of the flyers were from me. I'm going to have to get to know this rifle a little better. I caught myself jerking the trigger very deep into the pull. It seems like it takes forever to finally let go. Must different than all my bolt guns. I guess I didn't realize how much I have programed myself to the feel of a Remington 700.

 

[BBJones13]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: InfiniteGrim</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gnhowell1</div><div class="ubbcode-body">Try some 75 gr Hornady hpbt's. They seem to work a little better than the 77's for me. </div></div>

What kind of accuracy you getting with them. I personally have had problems with horrible consistency. I have shot .4moa 5 shot groups, but then the next will be 1.5-2moa. </div></div>

I find 77SMK's and 77 Noslers to be superior to 75 Hornady's. Not sure if the Hornady's I had were bad but the bullet weights varied far more than Noslers and SMKs and I think they are less concentrically weighted (that is just a guess). That said all are pretty good bullets to try.

 

[BBJones13]

Re: New AR/Fighting with 77grn SMKs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlamb</div><div class="ubbcode-body">Well took the AR up yesterday and tried 10 different load with 2 different powders. I've settled on 77SMK w/24grains of CFE223. I shot 5 round groups vs the 3 I was shooting before. There was no correlation between flyers and magazine/load positio.

One thing I noticed is that most of the flyers were from me. I'm going to have to get to know this rifle a little better. I caught myself jerking the trigger very deep into the pull. It seems like it takes forever to finally let go. Must different than all my bolt guns. I guess I didn't realize how much I have programed myself to the feel of a Remington 700. </div></div>

what trigger do you have in your AR?

 

[mrhog]

Re: New AR/Fighting with 77grn SMKs

It seems to me that maybe everyone is overthinking the problem here. The issue might be as simple as the rifle just doesn't like the 77gr. bullets.
Maybe you should try 75smk or another brand of match projectiles. Is there some reason that you are hell bent to use the 77gr.?
Anytime you can K.I.S.S.

 

[ssatt68]

Re: New AR/Fighting with 77grn SMKs

Here you go
http://www.jprifles.com/1.4.8.1_ezt.php

 

[jlamb]

Re: New AR/Fighting with 77grn SMKs

Trigger is s custom. I'm just not used to it. I need to dry fire at home for a bit.

I do have a Timney on my AR-10 that I quite like. I could swap, we'll have to see.

Mr. Hog, I've tried the 77gr Nosler Custom Competitions, 69 gr SMKs, 55 gr Sierra BlitzKings, and will try HDY 75 HPBT next weekend. Something has to work right?

Below is where I'm at with CFE223 -

Below is where I'm at with RL15 -