What’s your 223/556 gas gun sub-MOA set-up?
- Thread starter LAV
- Start date
I can get sub-moa with my CORE15. Here are the details.
Ammo:
-Hornady 68gr BTHP bullet
-24gr IMR4895
-Federal brass
-CCI small rifle primer
-OAL 2.25 (fits in the magazine)
RIFLE:
-Core15 TAC M4
-16" chrome lined M4 profile barrel
-free float quad rail and some harris clone bipod
-internals are all stock (trigger, bcg)
OPTIC
-Bushnell Elite Tactical 10x40 mounted on a Burris PEPR mount
I was able to produce a little less than .75 MOA at 100m, very close to .5 MOA while developping a load for the rifle and able to stay MOA up to 300m if I do my part that day.
Ammo:
-Hornady 68gr BTHP bullet
-24gr IMR4895
-Federal brass
-CCI small rifle primer
-OAL 2.25 (fits in the magazine)
RIFLE:
-Core15 TAC M4
-16" chrome lined M4 profile barrel
-free float quad rail and some harris clone bipod
-internals are all stock (trigger, bcg)
OPTIC
-Bushnell Elite Tactical 10x40 mounted on a Burris PEPR mount
I was able to produce a little less than .75 MOA at 100m, very close to .5 MOA while developping a load for the rifle and able to stay MOA up to 300m if I do my part that day.
I can get my stag 3g to shoot sub-moa, on average, sometimes. Sometimes the groups open up to 1 to 1.25 moa; other times, I am getting .5 moa. The loads are handloaded 69gr SMK's with about 5% less varget than a max load. The barrel is a match barrel with no chrome lining. My BCL 102 is about the same. Some groups are really tight in the .5 to .75 range, then the next go, they're about 1.25 to 1.5. I put on an aftermarket barrel (match?) in 6.5cm and triggertech trigger. I haven't completely figured out the voodoo behind a good semi. JP Enterprises sells bolts that are headspaced and matched to your barrel, I think that would help. Some say it's the play between the upper and lower; others say that is stupid. Some say it's the upper and the tightness of the barrel extension in the receiver; others say that also is stupid. I don't think either are stupid, as the process in getting a bolt-action to shoot makes sure that everything is tight and square.
Bolt gun voodoo is a no-brainer. My bolt gun will shoot .25 to .5 inch 3 to 5 shot groups, while a 10 shot group can open to about .75 or so. If it's in some sort of aluminum bedding block or chassis, get the thing torqued tight; if conventional stock, glass-bed. Make sure your action is square and the barrel threads are square. Then make sure you have a good barrel that is also square. Straight forward, but lots of skill required. And of course, in both, free-float the barrel.
For the stag, I've used winchester brass. I've also used range brass. I couldn't tell the difference between the two when shooting. I could tell the difference when loading as I hate swaging range/military brass primer pockets...
Bolt gun voodoo is a no-brainer. My bolt gun will shoot .25 to .5 inch 3 to 5 shot groups, while a 10 shot group can open to about .75 or so. If it's in some sort of aluminum bedding block or chassis, get the thing torqued tight; if conventional stock, glass-bed. Make sure your action is square and the barrel threads are square. Then make sure you have a good barrel that is also square. Straight forward, but lots of skill required. And of course, in both, free-float the barrel.
For the stag, I've used winchester brass. I've also used range brass. I couldn't tell the difference between the two when shooting. I could tell the difference when loading as I hate swaging range/military brass primer pockets...
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Norc M4 with a few changes to the recoil buffer and spring... adjustable gas block... and furniture. The BCG and lower parts are factory.
Most important part McGowen match barrel.
Completed the CGN AR sub MOA challenge a couple of years back... There was another target with 4 more 5rds groups under 0.75".. I think the 9 group (45rds) average was sub 0.7". used handloads with Berger 73gr bullets.
Again, another McGowen match barrel swapped into a BCL with pretty much all factory parts except for the adjustable gas block. handloaded 6.5 Creedmoor.
Barrels and chambers matter a whole lot more then the various bolts and innards of the upper and lower. Feed these proper ammo and the AR's can shoot.
Jerry
Attachments
With AR-15s, you also need to consider POI shift. With a heavy barrel, a light upper and a long handguard, you may experience a POI shift when you move the bipod from the front of the handguard to the rear (or shoot off of a barricade).
Honest question, Kris, why is that? If the barrel is freefloated, what causes the POI shift?
Torque. The barrel and the handguard are connected at the same place. Put torque on either of them and it affects the POI with a standard light walled receivers a lot. The heavier the setup and the longer the handguard, the more it is noticed. That is why a lot of guy run the thick walled DPMS uppers, Seekins IRMT or monolithic uppers. I think Vltor also makes a heavy walled upper that people use.
Try some experiments with it and you will see. I only have Seekins IRMT at the moment, but even with those, I have to be careful how I load the rifle on barricades. It will shift if I put downwards pressure on the front as I like to do on my MPA chassis on boltguns. With my buddy's thin walled uppers and a 15" handguard, the shift happens just moving the bipod to the rear. I'm using Sawtooth Rifles ARCA rails and an MPA RAT mount, so it's an easy test to run.
https://www.precisionrifle.shop/store/p32/Sawtooth_Rifles_Forend_Rail:_Seekins_15"_SP3R_.html
Try some experiments with it and you will see. I only have Seekins IRMT at the moment, but even with those, I have to be careful how I load the rifle on barricades. It will shift if I put downwards pressure on the front as I like to do on my MPA chassis on boltguns. With my buddy's thin walled uppers and a 15" handguard, the shift happens just moving the bipod to the rear. I'm using Sawtooth Rifles ARCA rails and an MPA RAT mount, so it's an easy test to run.
https://www.precisionrifle.shop/store/p32/Sawtooth_Rifles_Forend_Rail:_Seekins_15"_SP3R_.html
Robert Whitely alludes to it in this article: http://bulletin.accurateshooter.com/2015/05/what-makes-an-ar-accurate-whitley-offers-answers/
Rifles with thin walled regular receivers can still shoot tight groups, but those groups may shift all over the place if you're loading the rifle in different ways the way you would in a PRS Gas Gun match. You will probably never notice it if you're always just shooting the same way off the bipod prone or from a bench with the bipod always in the same spot.
Rifles with thin walled regular receivers can still shoot tight groups, but those groups may shift all over the place if you're loading the rifle in different ways the way you would in a PRS Gas Gun match. You will probably never notice it if you're always just shooting the same way off the bipod prone or from a bench with the bipod always in the same spot.
My AR can run consistent sub MOA with handloads for it as well. Is not a cheap set up but runs like a clock.
It’s a JP Enterprises factory build, 22” factory cryogenically treated heavy barrel, adjustable gas block which I run as low as possible, just barely enough to let it cycle, silent capture spring, Magpul PRS Gen 3 stock, Triggertech lightweight trigger, LRA F-Class bipod, Ergo grip, with a Zeiss V6 scope. Likes 77 Smks and Berger Fullbores, both loaded long. Single feed at these lengths. Easy to do with a Magpul Bad lever installed.
The JP also comes with the LMOS bolt, (low mass operating system), which is tunable with the silent capture spring, to reduce reciprocating mass and lesson the impulses going thru the rifle. Every little bit helps with overall accuracy.
It’s a JP Enterprises factory build, 22” factory cryogenically treated heavy barrel, adjustable gas block which I run as low as possible, just barely enough to let it cycle, silent capture spring, Magpul PRS Gen 3 stock, Triggertech lightweight trigger, LRA F-Class bipod, Ergo grip, with a Zeiss V6 scope. Likes 77 Smks and Berger Fullbores, both loaded long. Single feed at these lengths. Easy to do with a Magpul Bad lever installed.
The JP also comes with the LMOS bolt, (low mass operating system), which is tunable with the silent capture spring, to reduce reciprocating mass and lesson the impulses going thru the rifle. Every little bit helps with overall accuracy.
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Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Was either a JP or a Yankee hill... again, doesn't matter as it is a very crude device that just reduces the gas flow to the BCG. If the gas block you have is wide enough, just drill and tap for a bolt to cover the port... that's it.
An AR looks all modern but operation is really very simple and that is exactly why current ARs can run and run and run. And can also be made to shoot very accurately not far off bolt rifles.
In any type of competition shooting, the 3 B's matter - Barrels, Bullets and Bedding... an AR is one of the few semi autos where you can focus on these three areas for success.
As k has indicated, a typical "thin" AR lower will flex if you hang a honking big varmint or match barrel 26" off the front... it was never designed for that load. But your typical mod HBAR or HBAR contour that finishes around 20" isn't going to cause any grief.
The upper has a very nice "egg" shape to it so it can handle a far amount of bending load... just don't get carried away and hang 10lbs of barrel and accessories off it.
As for bending in positional shooting, no clue but that would be one heck of a lean into the barricade to cause anything of quality to flex. I certainly haven't seen those issues in horsing around with my Norc... but anything can flex if pushed hard enough.
Been following the AR "precision" side for several years and in Canada, the approach is way off vs what is happening in the US. They take quality sub MOA AR's for match competition as a given... no big deal.
Shilen and Krieger have been making barrels that win at the highest levels of US AND Cdn competition for several years. McGowen is coming on strong over the last couple and offering great shooting barrels for not much more then other "match" barrels. IBI is working on a Cdn alternative
For those serious about AR and accuracy, forget about the bling and spend the money on quality match barrels with the right chambers and twists. Learn to reload at a precision shooting level and tune the AR accordingly.
USGI spec AR parts are dimensionally very similar... at least they should be. Materials are similar if they are going to function at any level. Gold plated doesn't help
I have had a surge of interest in the barrels I can offer since the NR AR's have come on strong... many are super interested in the type of accuracy my projects have delivered but shy away when they can get a "match" barrel for quite a bit less money. Unfortunately, not many are reporting consistent accuracy even with handloads.
Barrels, bullets and bedding... they matter. The least expensive options are rarely the best choices
YMMV.
Jerry
Cool, thanks for that. I'd never really looked into anything to do with those integrated handguards, not had I though about receiver flex. I hadn't thought much about precision ARs simply because we're stuck taking them to the range. With the new NR options coming out though, especially something like that new Stag 10, I'm kinda itching to do a precision build in 6.5, haha. Oh and Matt at Sawtooth makes great stuff, those guys are "local" to us in the PNW.
Great thread on the topic of receiver flex over on the hide as well:
http://forum.snipershide.com/threads/accuracy-and-upper-receivers.6888138/
I'm wondering what, if any, effect a full length swan rail like the MK12 had would have on the flex. I'm assuming it would help dramatically if it is a well-made part.
http://forum.snipershide.com/threads/accuracy-and-upper-receivers.6888138/
I'm wondering what, if any, effect a full length swan rail like the MK12 had would have on the flex. I'm assuming it would help dramatically if it is a well-made part.
morganlamprecht's post #43 shows it well.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Now how much is due to rifle flex vs POI shift due to change in recoil?
you can easily move your group around when using a Harris and bolt rifle by how you load into the bipod. Definitely no rifle flex there. Why they need so much finese to shoot them well... and why I am not in a hurry to get spiked feet on mine.
Not saying the AR isn't flexing but if you lean 200lbs hard into a rifle, the recoil impulse of the rifle is WAY different then a light shoulder hold and that changes barrel harmonics which change POI regardless of rifle flex. Not sure why you would need to lean that hard regardless????
I appreciate that leaning into the rifle can add some stability but inconsistent pressure on the buttstock affects the recoil follow through and that leads to shots going somewhere else. I would learn to be consistent regardless.. and push just "enough" to get the job done... anything more just opens me to trouble.
Spend a bit of time with a rimfire and you can do that just by how hard you grip the stock.
Jerry
I know my MV is not an AR but it's close enough to be relevant to the discussion.
I completely agree with what you say about NOT "loading" down on the rifle. When I first got it I shot it with my right hand on the grip and trigger and my left hand on the handguard pushing downward and pulling rearward. My thoughts were to keep the rifle from moving as much as possible. Needless to say I wasn't impressed with how it shot. Plus I noticed flyers due to gas block contacting the handguard during recoil. It was good but I still believed it should be able to do better. And it did do better once I learned how that rifle likes being shot.
The following are two 5 round groups and 1 ten round group shot from 1 box of ammo at 200 yards. The 3 targets weren't cherry picked from the best of the day. It was 20 shots from 1 complete box of ammo. Shot from prone with the rifle in line with my body, right hand on the grip and trigger and the left hand under the buttock for stability. There was NO downward pressure put on the rifle and the only rearward pressure was done by pulling into my shoulder with my shooting hand. So basically just enough rearward pressure to stabilize my shot. Plus no more flyers from gas block contact.
View attachment 189387
View attachment 189388
View attachment 189389
The 10 shot group opened up to approx 1 moa due to the pencil barrel.
If I keep my shooting position consistent and the little rearward pressure that I do apply consistent AND I basically let the rifle free recoil it will do this every time. Start "loading" pressure to the rifle and there is no doubt that groups start to open up compared to this. I don't usually takes pictures of groups but I did this time just to show what I could do with 1 box.
And yes, if you noticed, that is factory ammo. At 200 yards. Near perfect day with less than 5 mp/h cross wind. Flame away if anyone wishes but once you learn how a rifle likes to be shot you will see it's true potential.
EDIT: I've found that off the shelf so called "match" grade barrels seldom if ever perform as well as a top of the line barrel that costs you actual money. A top quality barrel combined with the shooting technique that your rifle likes will provide you with the best results
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