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Old 12-17-2010, 17:38   #1
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AR-15 tune for accuracy

I'm not into tacticool. No problems with it, just don't feel the need to trick out my rifle with every new gadget that comes along. The question I have is this, has anybody else found that their AR (not free floated) shoots better off a sandbag rest without the handguard? Just out of curiosity I fired mine without them the other day, tucking the sandbag just in front of the mag well. Suddenly Federal bulk ammo (55gr FMJ) went from 3 inches w/ to around 1 1/4 w/o. Will installing a free float handguard give me the same sort of benefits?
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Old 12-17-2010, 18:26   #2
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Don't know!If your barrel/chamber was resting on the sand bag then what you did was effectively to change your barrel harmonics-specifically dampening the barrel with the sand bag.One question tho-did your 1+1/4" group start to string upward?
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Old 12-17-2010, 21:13   #3
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No stringing. Just round to slightly oval from 9 - 3 o'clock. The barrel was cryo'ed so I rarely get vertical strings unless I screw up or my loads aren't consistent. Even then the stringing doesn't show much till I get out past 100 yards. Shouldn't be getting too much dampening with the the majority of the barrel hanging out in front. I should have been clearer. I'm using a rest supporting a small sand bag - which the supports the rifle. The bag didn't extend out past the chamber area by much - Hard to tell, it's a heavy barrel with no taper there.


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Old 12-18-2010, 14:43   #4
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Another question about tuning an AR for Accuracy - I know how to dress up a bolt gun's lugs to get full contact. Do you do an AR the same way (multiplied) or does it even affect AR accuracy? I want to get mine shooting consistently sub-MOA.
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Old 12-18-2010, 15:12   #5
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To answer your question, yes, free floating improves accuracy. Relieving any force off the barrel can help. Unless you have a skinny barrel the cyro treatment is very questionable. I can't say that I have heard of many AR operators that do it.
I haven't heard of any bolt tricks. A good barrel and ammo gives the AR15 very good accuracy.
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Old 12-18-2010, 16:05   #6
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My 16" barrel is heavy under the hand guards and is reduced to standard from there forward with an A2 front sight and birdcage flash hider. I felt it might benefit from cryo because it was strings shots vertically as the barrel heated. When it came back, this tendency was gone.
Dressing the bolt lugs isn't really a trick, it just gets even engagement on all the lugs, preventing the bolt from flexing during the shot. This does help accuracy with bolt guns and service rifles like the M1, M14, as well as the Mini 14. It's not real noticable until your gun is shooting decent groups anyway, but it's just one more variable to eliminate.

Dave
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Old 12-19-2010, 16:08   #7
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briflemn,

Pretty interesting stuff here. You're the first guy I've ever known that tried to shoot without the handguard to see how accuracy would be without it. The general consensus is that free-float handguards increase accuracy so if that's what you're after, go for it. It's a bit of gunsmithing and $$$ to do it, but it may be a walk in the park for you.

Also, you need your lower and upper to fit TIGHT if you want more accuracy. By tight I mean that you will need to use a hammer and punch to pop out your takedown pin. This can be done with "accuwedges"-- which can be purchased and replaced as they wear out-- or by using epoxy compound to glass bed your contact points between the upper and lower to form a precise, tight fit.

Lastly, what kind of trigger are you using? You didn't mention anything about your trigger so I thought I'd ask. Again, interesting stuff here and I look forward to hearing more.

MDJ

Good luck and keep us posted.
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Last edited by MadDogJohn; 12-19-2010 at 16:11.
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Old 12-19-2010, 19:08   #8
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I'm using a Bushmaster lower with a DCM match trigger that I've polished till I got a 3.5 lb pull. I do have an accu-wedge installed and have been considering bedding the upper and lower together. I haven't decided whether something like accuglass or a steel bedding compound like Brownell's sells or even JB weld would work best. Any tips?
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Old 12-20-2010, 19:29   #9
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briflemn,

There's an article in Shotgun News from last spring called "Ultimate Warriors Rifle" by Phil Arrington. Good stuff there for what you're looking at doing with yours.

You might do better, but this was all I could find. No pics, but the part about the glass bedding begins about halfway down.

Warrior's rifle? When a sniper off to the wilds of Afghanistan asked for an exceptionally accurate and reliable rifle, this Arizona gunsmith chose the Colt LE 6940 as a starting point. - Free Online Library

Hope this helps.
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Old 12-20-2010, 19:51   #10
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Thanks. I'll give it a look.
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Old 12-20-2010, 21:23   #11
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Originally Posted by briflemn View Post
Thanks. I'll give it a look.
Good info there and I may try it here soon. Have your ever tried one of those tensioning rear pins from Bushmast or JP Enterprises?

Dave
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Old 12-21-2010, 22:11   #12
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Originally Posted by briflemn View Post
Good info there and I may try it here soon. Have your ever tried one of those tensioning rear pins from Bushmast or JP Enterprises?

Dave
I'm glad you brought those up. I kind of forgot about them but I've heard good things about them. I just finished a varmint build and the upper/lower fit is tight enough that I have to use a punch to knock it out. Eventually, that'll wear out and I'll need to fix it.

I have another completed lower with the standard A2 stock that I want to finish off with a 20" DCM/NM upper with iron sights. That will be a good candidate to maybe try the rear tensioning pin.
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Old 12-22-2010, 06:50   #13
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I think I'm going to try one of those before I bed it. It seems to me that would be a better option for a lower I may switch out uppers on - unless I were to put the bedding materiel on the upper instead of the lower. Seems that may be a little more complicated.

Dave
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Old 12-22-2010, 06:58   #14
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A tight upper to lower fit will NOT produce a more accurate AR15!
It's a BS myth, completly incorrect info.

It's all about barrel, bolt, receiver face squareness & ammo that the rifle likes.
A good trigger, proper cheek weld & good sights and/or optics helps as well.
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Old 12-22-2010, 11:08   #15
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Originally Posted by faawrenchbndr View Post
A tight upper to lower fit will NOT produce a more accurate AR15!
It's a BS myth, completly incorrect info.

It's all about barrel, bolt, receiver face squareness & ammo that the rifle likes.
A good trigger, proper cheek weld & good sights and/or optics helps as well.
Where the problem comes in is when you have a very loose fit. I have seen rifles where there is enough play between the upper and lower and you can move the front sight around and change point of impact. The AR180 suffers from sloopy fit. For most AR's I can't see it being a problem and glass bedding doesn't seem all that practical. You can correct the problem with different pins or simply adding an accuwedge
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Old 12-22-2010, 15:40   #16
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briflemn,

With regards to your original question about a free-float handguard giving you the same benefits as removing your handguards, the answer is that, yes, it should (as Carbine85 has already stated). In fact, free-floating the barrel would be one of the first upgrades I would consider for your rifle.

You may also want to consider getting your rifle's barrel cryogenically treated (aka: "cryoed"). This acts as an additional "tempering" process for the metal in the barrel. As a result, at the composition level, the steel will be enhanced by converting residual austenite (which is brittle) into the stronger martensite. Here's a decent reference that explains it more thoroughly:

Click here

There are a few good places that offer Cryogenic Tempering. I use CryoPro myself; David H. is a great guy to work with. There is also 300Below, and despite not using them myself, I have read positive comments about them.

Aside from getting a free-float handguard installed, and getting your barrel cryoed, I would also install a really nice match trigger. Rock River Arms makes a very good one for a reasonable price, but there are others out there...which will cost you a pretty penny (e.g. Chip McCormick and Geissele).

Of course, consistency equals accuracy. And, this is where getting yourself a stock that is comfortable and that you like to shoot with is important. I prefer an A1/A2 style AR-15 stock for both accuracy and bench shooting, as it provides a nice check weld for me. (YMMV)

I won't touch on optics, as personal preferences play heavily into the equation. Besides, there are a TON of options and products to choose from. If you're going with good 'ol fashioned iron sights, a good National Match front and rear sight set would probably be in order for your rifle. However, if you're looking for sub-MOA accuracy, I'd say an optic is in order.

With regards to upper and lower receiver "slop", the rear tensioning pin from J.P. Enterprises seems to be a good idea. However, as a simpler solution, many AR-15 shooters use the Accu-wedge. The bedding idea sounds interesting, but from what I've read about it, it appears that once you do that the upper and lower half are sort of "married" together. In other words, swapping out uppers probably won't work well.

BTW, I too have also read that the "fit" of AR-15 upper and lower receivers is not as crucial as some may believe. Alternatively, I think you'll get more noticeable gains in accuracy with addressing the items that are mentioned here. (Just an opinion of course.)

That said, if the "slop" is noticeable and it is driving you nuts (as it would for me), try the Accuwedge first, as they're fairly inexpensive. If that doesn't work, try the rear tensioning pin next. Frankly, I'd leave bedding to the last resort, but that's me.

Anyway, I'd say start with free-floating the barrel. Of course, it sort of goes without saying, but ensure you have a good barrel start with. Next, consider cryo-ing the barrel; the science behind it does add up. Next, get a good match trigger. Next, find a stock that offers a comfortable and consistent check weld. And, finally, make sure to get plenty of range time to shoot your rifle.

Do all this...and I'm betting you'll get your rifle to where you want it to be. If not, it'll be darn close!

OK...Probably more than you needed, but what the heck...that's why we're here.

Happy Holidays!
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Old 12-23-2010, 13:44   #17
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alaj70

Darn fine post,............good info.
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Old 12-23-2010, 17:15   #18
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Alaj, you are one wicked smart guy! Great information as always!
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Old 12-24-2010, 01:30   #19
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Originally Posted by faawrenchbndr View Post
A tight upper to lower fit will NOT produce a more accurate AR15!
It's a BS myth, completly incorrect info.

It's all about barrel, bolt, receiver face squareness & ammo that the rifle likes.
A good trigger, proper cheek weld & good sights and/or optics helps as well.
When I saw this reply I thought What the hell?!

I've been led to believe the fit between the upper and lower was very important to accuracy-- or precision. All the serious civilian competition shooters and the military competition teams swore by their accuwedges and bedded upper & lowers. I took it as gospel. And reading good articles like the one Phil Arrington(an experienced and highly regarded gunsmith) did for Shotgun News just re-inforced my opinion.

But faawrenchbndr's response was fair game. Hey, that's what makes PU a great forum. We might get our feathers "singed" every now and then, but most of the time we end up finding some truth and learning something along the way. Or we at least try to agree to disagree and move on. (unless it's and AR vs. Mini thread.

So I did some searching and asking around about this issue and I will say I have been re-opinion-ated. Yeh, I know.... I pulled a "Bush" and made up a new word.

Here's a quote from the USAMU website:

Q: I would like to know if bedding or an Accu-Wedge is necessary for the service rifle (M16)?
Thanks You
Bob

A: Bob,

The use of bedding compound or an Accu-Wedge is not necessary for an M-16. We have fired the rifles with and without these products and have noticed no effect on accuracy. Most of us choose to use an Accu-Wedge simply because we don't like the movement between the upper and lower receivers, even though it does not affect the accuracy of the weapon.

I do not recommend the use of a bedding compound. If you are like a lot of shooters, you may have multiple upper receivers and only one or two lower receivers. You may find with the use of bedding compound in the lower receiver, not all of your uppers will be compatible with that lower anymore. Our shop formerly used bedding compound and later realized that not all of our uppers could be put on all of our lowers anymore. The Accu-Wedge will tighten up the slop between the two receivers, but remains pliable enough that it can be used with any upper and lower receiver combination.

SFC Kyle Ward

http://www.odcmp.com/USAMU/Equipment_Ammo.htm

And I talked to a Marine vet friend and he said he used to shoot "smiley faces" on the range targets with his well-worn, rattletrap M16A2 when he was serving twenty years ago. He said he always qualified with that rifle and it never let him down. But he did say that having a tight upper and lower did have a "psycholgical" advantage for some guys because they were used to, and grew up with, solid-feeling bolt action rifles and shotguns.

That makes a lot of sense. I can see how having a tight upper/lower will have little to no mechanical advantage for a more accurate AR, but might give an edge in the "headgame" for some shooters-- and that's fine. Whatever helps. Me? I think I'm not going to worry so much about the fit between the upper and lower anymore. But I'll understand why it works for some shooters who swear by it.

Good thread.
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Old 12-24-2010, 04:03   #20
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Great post MadDogJohn,.......

Remember, I'm just a regular Joe when I post. I try to be courteous & resectful.
And,.......I like a good debate!

I compleately agree with, "but might give an edge in the "headgame" for some shooters"

Very good insight,......it a tighter fit make you a more confident shooter, then the small part was worth it.
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Old 12-24-2010, 05:31   #21
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Originally Posted by faawrenchbndr View Post
Great post MadDogJohn,.......
What he said.

I've been reading this thread and trying to figure out how bedding an AR would be a plus, considering how it all goes together. I now have my answer. Thanks, MadDogJohn.
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Old 12-24-2010, 06:41   #22
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Originally Posted by faawrenchbndr View Post
A tight upper to lower fit will NOT produce a more accurate AR15!
It's a BS myth, completly incorrect info.

It's all about barrel, bolt, receiver face squareness & ammo that the rifle likes.
A good trigger, proper cheek weld & good sights and/or optics helps as well.
+1

I've seen guys (and gals) constantly shoot excellent groups while qualifying with service M16a2s that were literally falling apart.

A tight rifle with a nice trigger helps, but consistent technique is the way to get the bullet repeatably onto the target, IMHO.
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Old 12-24-2010, 08:03   #23
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Originally Posted by kenl View Post
+1

I've seen guys (and gals) constantly shoot excellent groups while qualifying with service M16a2s that were literally falling apart......
We mostly had the M16A1 & a few Carbines, all were very loose. I qualified expert in '86
Finally got to shoot an A2 in the mid nineties. They were quite a bit tighter, but no where near
as tight as most of the AR15's are today.
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Old 12-24-2010, 11:42   #24
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A good trigger will also go a very long way in shrinking those groups. It would be the first change I made. YMMV.
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Old 12-24-2010, 13:02   #25
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Hey guys - thanks for all the input. The barrel has already been cryo'ed to fix a vertical stringing issue. I've been shooting with an accuwedge for years - more of a psych thing than anything else. I cut my teeth on M-1's and M-14's. I was on the Air Force team years ago, but retired before the switchover from M-14;s to M-16 took place. In fact, the first time I qualified with an M-16, all the weird sounds in the stock made me call a malfunction. Boy, did I feel dumb when I found out it was normal.

Anyway, The first thing I'm going to do is free float the barrel. It seems pretty decent although I'm not sure who made it. I may also hone the tight spots out. There's a pretty bad spot where the taper pins are pressed in.

Dave
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