Gf wants a light ar, I don't want to break the bank :p

ColoradoMinuteMan said:

The most common break point for polymer lowers is between the takedown pin and the back of the grip. I'd be interested to see how this resolved with the one piece lower because I don't know that having the stock integrated into the lower would actually make that particular break point any stronger.

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The GWACS lowers are much more massive than the polymer lowers that are the same dimensions as aluminum. The threaded portion where the receiver extension/buffer tube threads into a lower is too weak when made of polymer. I have seen several pictures of broken 'plum crazy' lowers.

Of course if you are building a 22lr plinker the polymer stuff is fine. I generally like a little more heft in my stock, so I don't own one, but I would not worry about breaking a GWACS lower.

hq said:

A properly installed and torqued, free floated quality barrel doesn't lose its accuracy or change POI when it gets hot. It might when it's glowing orange, but that takes at least a couple of C-mags' worth of sustained full auto fire even with a pencil profile barrel. I can't really see anything like that happening in semi auto, regardless of the discipline or intensity of competition or stage. Some low and medium quality barrels string like there's no tomorrow at moderate (150-300°F) temperature changes, especially when they're supporting the handguard and the shooter changes the way he holds the gun and consequently the tension on the barrel.

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Sorry, that's simply not true.

High end manufacturers go to great lengths to avoid or alleviate stress in their barrel steel, but all of them will tell you that a more rigid barrel will exhibit less dispersion when you get it hot. And it doesn't have to be glowing orange to witness it either.

Pencil barrels will also cause more heat mirage coming from the barrel and effecting your view through the scope. If the target is dancing around, which one do you shoot at?

ontarget said:

I still recommend checking out the OMNI by ATI. Poly receivers have come a long way. According to my LGS the parts are all interchangeable with standard AR receivers.

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A receiver is the last place that I would cut weight. The weight that feels 'heavy' on an AR is the weight of the barrel, and to a lesser extent the optic.

The contour of the 16" barrels that Palmetto calls A2, really doesn't seem as thick as an A2 to me. I don't have a 20" A2 barrel here to compare, but I do I have a 16" Palmetto barrel and it balances nicely for me. I will go hand it to my wife and see what she thinks of it.


That's not to say that I don't like GWACS lowers. They are fine and I would consider one myself if I were doing an ultralight build. That is probably the only polymer lower I would consider.

bhhacker said:

I'd really love to get something relatively light weight so she's into shooting it more. She gets tired and has terrible groups with my heavier guns. What are you guys thinking? I'm not looking for the lightest one in the world, just lighter than usual if that makes sense. Limit of 6 or 700 without sight/optic but ideally less would be nice.

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Very timely question. I have been working on a parts list to also build a lighter weight AR. It can get expensive for shaving a few grams in weight.

First I have choose to stay with a metal lower receiver as I want the extra strength and durability even though it weighs a more than polymer one.

The four main parts to save weight I have choose so far are;

1. Mission First Tactical Minimalist Stock - weight 6.0 ounces

2. *MOE-SL Carbine Length Handguard - weight 6.7 ounces

3. 16" pencil profile barrel to be determined.

4. Slickside Upper Receiver (no forward assist and no dust cover) - weight 6.88 ounces with brass deflector.

*Still reviewing handguards. I really like how Magpul feels.

At the moment I don't see the need for titanium small parts as I don't feel the weight saving is worth the extra cost.

Parts weights are based on information from manufacturers and venders

IndianaBoy said:

Sorry, that's simply not true.

High end manufacturers go to great lengths to avoid or alleviate stress in their barrel steel, but all of them will tell you that a more rigid barrel will exhibit less dispersion when you get it hot. And it doesn't have to be glowing orange to witness it either.

Pencil barrels will also cause more heat mirage coming from the barrel and effecting your view through the scope. If the target is dancing around, which one do you shoot at?

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Oh yes it is. The combination is a sum of a number of factors. The more rigid the barrel the less its resonation behavior is dependent on the properties of ammo and the less deviation from static bore line there will be when the bullet travels through it. On the other hand that doesn't necessarily matter providing that harmonic resonation is uniform and at the same phase when the bullet exits. The combination of solidifying environment in casting phase of billet and machining operations performed to form a barrel, especially any forming that's done to the steel in low temperatures, create tension in the crystal structure which leads to non-uniform expansion in function of temperature. There are a number of ways to relieve the stress by temperature cycling of finalized product, based on recrystallizing the structure. Cryogenic cycling is an effective but a very costly method to achieve uniform, low-stress crystallization and used mainly on higher end barrels.

In short, moderate temperature changes have very little effect on the accuracy of high quality barrels, even most slim profiled ones. Of course they heat up faster (doh...) and have less tensile strength to resist stress- and heat-induced distortion so it's imperative that all steps are taken to have crystal structure stresses eliminated. Very accurate and temperature-insensitive pencil barrels do exist but they're rare and few manufacturers bother to test fire and hand-pick the exceptional ones or cryo their finished products. It's just so much easier to make a bull barrel and rely on sheer mass an rigidity to counter the likely, almost inevitable defects in the steel.

The ATI upper and lower receivers are definitely now steel reinforced at all stress points.

ColoradoMinuteMan said:

The most common break point for polymer lowers is between the takedown pin and the back of the grip. I'd be interested to see how this resolved with the one piece lower because I don't know that having the stock integrated into the lower would actually make that particular break point any stronger.

Click to expand...

Just from the outside perspective, the GWACs has more support in that area. Another thing is that a polymer lower that replicates a metal lower doesn't have the grip as part of the structure like the GWACs lower receiver does.

View attachment 774868

If you haven't already decided, this upper paired with the lower, BCG, and charging handle of your choice would make a good basic lightweight rifle for easily under 500.

http://palmettostatearmory.com/psa-...ecision-m-lok-freedom-upper-no-bcg-or-ch.html

bhhacker said:

My gf is taking some interest in shooting and would like to have a rifle just in case. With the price of ar parts being pretty darn low I figures I'd help her out. I'm an Ak guy though normally and do not know a lot about what's on the market currently. I know I can do a complete upper and lower from psa for pretty cheap but I'd really love to get something relatively light weight so she's into shooting it more. She gets tired and has terrible groups with my heavier guns. What are you guys thinking? I'm not looking for the lightest one in the world, just lighter than usual if that makes sense. Limit of 6 or 700 without sight/optic but ideally less would be nice. Thank you for your time.

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It has already been said, but I think a Faxon Pencil Barrel would be a good choice to save a lot of weight right off of the bat. You can also save significant weight in the hand guards without much investment... I run an ALG Defense aluminum modular rail on one of my guns and it is pretty darn light for the price (naturally you can spend $300 or so for a hand guard and get a much lighter carbon fiber one, but you'll pay a LOT more to save that weight).

You should note that you play a game of diminishing returns when you jump into building an ultralight rifle. You can save some pounds up front pretty cheaply by going to a shorter barrel with a thinner profile, and things like that. But, when you start trying to save every conceivable ounce, the price can skyrocket pretty quickly.

I'm slowly parting together a rifle for my wife, who also doesn't like heavy rifles. So far I have a Faxon pencil barrel in the mix, and a Brigand Arms Edge hand guard. The barrel wasn't obscenely expensive, and certainly no more so than a regular profile barrel. As such, I saved a pound or so for virtually no cost there. But, the hand guard retails for around $300. It saved a good amount of weight (6 ounces less than the lightweight one it replaced), but it was relatively expensive to do so.

Similarly, when you start getting into ultralight bolt carrier groups and things like that you can certainly save a couple of additional ounces, but it might cost you a couple of hundred dollars to do so. You may also start to experience some reliability issues with these kinds of modifications.

So, how far should you go? That's really up to you! I'm striving for a sub-3.75 pound gun with my current build, and it will be costly to get there. But, it would be a lot less costly if I just decided to stay under 5 pounds, or 4.5 pounds.

ColoradoMinuteMan said:

Building or buying is going to determine your options. Your standard off the shelf AR15 with carbine gas system is going to weigh in at 6.5 lbs with iron sights. A mid-length gas system will add a couple of ounces. The weight is mostly in the barrel and a pencil profiled barrel will save you about 3/4 lbs and about 1/2 lbs with polymer receivers. The polymer receivers seem like the benefit outweighs the risks for me. Others obviously disagree and to each their own.

If the issue is groups opening up from fatigue it sounds like maybe a focus on shooting positions would help. The reality is that 1/2-3/4 of a pound really isn't going to make a tremendous difference in fatigue. My daughter has been shooting an off the shelf since she was 11 years old and she's not even close to being in athletic shape. Through training and the learning of different shooting positions and techniques, just about anyone should be able to go hours of shooting with an off the shelf AR15 before fatigue becomes a real factor.

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hq said:

Oh yes it is. The combination is a sum of a number of factors. The more rigid the barrel the less its resonation behavior is dependent on the properties of ammo and the less deviation from static bore line there will be when the bullet travels through it. On the other hand that doesn't necessarily matter providing that harmonic resonation is uniform and at the same phase when the bullet exits. The combination of solidifying environment in casting phase of billet and machining operations performed to form a barrel, especially any forming that's done to the steel in low temperatures, create tension in the crystal structure which leads to non-uniform expansion in function of temperature. There are a number of ways to relieve the stress by temperature cycling of finalized product, based on recrystallizing the structure. Cryogenic cycling is an effective but a very costly method to achieve uniform, low-stress crystallization and used mainly on higher end barrels.

In short, moderate temperature changes have very little effect on the accuracy of high quality barrels, even most slim profiled ones. Of course they heat up faster (doh...) and have less tensile strength to resist stress- and heat-induced distortion so it's imperative that all steps are taken to have crystal structure stresses eliminated. Very accurate and temperature-insensitive pencil barrels do exist but they're rare and few manufacturers bother to test fire and hand-pick the exceptional ones or cryo their finished products. It's just so much easier to make a bull barrel and rely on sheer mass an rigidity to counter the likely, almost inevitable defects in the steel.

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Thank you for making my point. It is almost impossible to make a pencil weight barrel that will shoot as well as a heavy weight barrel, unless you pick through many examples until you find the rare one that has all stress eliminated.


In the process of trying to disagree with me, you proved my point. Also thanks for pointing out that this mythical pencil barrel would by necessity be very expensive. I'm sure we will start to see these barrels on the line at matches, exactly never.


Thanks again.

chicharrones said:

Just from the outside perspective, the GWACs has more support in that area. Another thing is that a polymer lower that replicates a metal lower doesn't have the grip as part of the structure like the GWACs lower receiver does.

View attachment 774868

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Thats a pretty good illustration. It definitely makes it interesting. I don't have any interest in polymer, but if I did, I think would be a better option.

IndianaBoy said:

Thank you for making my point. It is almost impossible to make a pencil weight barrel that will shoot as well as a heavy weight barrel, unless you pick through many examples until you find the rare one that has all stress eliminated.


In the process of trying to disagree with me, you proved my point. Also thanks for pointing out that this mythical pencil barrel would by necessity be very expensive. I'm sure we will start to see these barrels on the line at matches, exactly never.


Thanks again.

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Not really sure what this has to do with my post, but ok!

The cav15 saves a ton of weigh two ways. One by being polymer and two by eliminating a whole slew of individual parts from a grip screw to the buffer tube and castle nut.

As pictured above it’s vastly stronger than other poly lowers that try to take standard grips and stocks

IndianaBoy said:

Thank you for making my point. It is almost impossible to make a pencil weight barrel that will shoot as well as a heavy weight barrel, unless you pick through many examples until you find the rare one that has all stress eliminated.


In the process of trying to disagree with me, you proved my point. Also thanks for pointing out that this mythical pencil barrel would by necessity be very expensive. I'm sure we will start to see these barrels on the line at matches, exactly never.


Thanks again.

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Not quite, so don't mention it. However, contrary to how you seem to have perceived this, extremely accurate slim profile barrels can certainly be manufactured intentionally. Upper echelon of hunting rifles is a prime example of this, with fluted pencil profile barrels that even carry accuracy guarantees. Weatherby Mark V and RC series, Sako Finnlight/Carbonlight, American Precision Arms TCG, Jarrett Signature and Long Ranger to name a few. Price range is quite a bit beyond anything a typical modern sporting rifle buyer is willing to shell out for a very accurate lightweight rifle, but on the other hand nothing prevents having a complete, finished barrel cryo-relieved ($50-100) and hand-lapped ($200 on up or straightforward DIY for pennies) for considerable improvements in initial precision as well as eliminating most if not all heat-induced stringing tendencies.

Slightly more elaborate than just whipping out a credit card and ordering a cheap bull barrel, but well worth it providing that you'll ever carry the gun more than a few miles in the field, tracking game etc. Of the dozens of AR15:s, M16:s and M4:s in my collection I've gotten lucky once; with a lowly run of the mill pencil profile AR15A1 with a late 1970's mfg date that shoots consistent sub 1" groups at 110yd with a variety of ammo from a steady rest as long as the pressure/grip on forend is uniform. Bore scope hasn't revealed anything out of the ordinary inside the barrel or in the chamber, it just seems to have received a barrel from an exceptionally good batch. It has never been subjected to full auto fire either and I got it in late 90's NIB so nothing has been done to it by the previous owner. A bit of an anomaly compared to the norm but not unheard of.

Accurate pencil barrels aren't anything mythical nor necessarily prohibitively expensive. They're out there and if you really want one, having your own made from a commonly available barrel isn't rocket surgery. If I wanted to make sure, I'd have one turned from a Krieger, Lothar-Walther or Lilja blank, chambered as tight as I'd dare, hand-lap it to an absolute mirror and have it cryo-cycled at least once, but my current go-to carbine (11" suppressed XM177-clone) can already deliver the combination of 2½" groups at 330yd, reasonable overall weight and compact size for carrying strapped on a backpack for snow/black/wood grouse hunting as well as varminting.

A while ago I mentioned my preference of results that can't be duplicated with any kid with a credit card and hand tools, but this falls into a category of being close enough; mainly because most kids so equipped never come across the thought of doing it this way.

hq said:

Accurate pencil barrels aren't anything mythical nor necessarily prohibitively expensive. They're out there and if you really want one, having your own made from a commonly available barrel isn't rocket surgery. If I wanted to make sure, I'd have one turned from a Krieger, Lothar-Walther or Lilja blank, chambered as tight as I'd dare, hand-lap it to an absolute mirror and have it cryo-cycled at least once, but my current go-to carbine (11" suppressed XM177-clone) can already deliver the combination of 2½" groups at 330yd, reasonable overall weight and compact size for carrying strapped on a backpack for snow/black/wood grouse hunting as well as varminting.

A while ago I mentioned my preference of results that can't be duplicated with any kid with a credit card and hand tools, but this falls into a category of being close enough; mainly because most kids so equipped never come across the thought of doing it this way.

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You should let the guys on the PRS circuit know. I'm sure they would love to be clued in.

What is interesting is although there were more people running Medium Palma barrels than any other, only 15% of those ended up in the top 20. Compare that with the fact that 67% (6 of 9) of the shooters running an MTU barrel ended up in the top 20! Heavy Palma also had a good representation, with 50% (6 of 12) of the shooters running a Heavy Palma ending up in the top 20.

There is certainly a question about whether that is correlation or causation, which essentially is just saying did those shooters place higher because they were using heavier barrels … or did the best shooters happen to be using heavier barrels. You’d likely need random sampling and a larger sample size to be able to answer that definitively, so I’ll leave it up to you guys to debate. Regardless of how much it impacted the results, one thing is undeniable: in 2014 the best precision rifle shooters in the country are choosing Heavy Palma and MTU barrels.

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ColoradoMinuteMan said:

Not really sure what this has to do with my post, but ok!

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Sorry, not trying to derail your thread. I posted links to two barrels that I think would fit your application well and not break the bank back on page 2.

I just don't like seeing misinformation spread.



For your purposes I think a pencil barrel will be an excellent choice. They are just a bit harder to find. Another thing to consider when she is shooting, give her a 20 round mag instead of a 30, and don't go too heavy on the optic. Red dots are nice and light. There are some light 1-4x scopes out there and there are some low powered scopes that are really dang heavy. I have one of them. I like it, but my wife wouldn't.

Another thing to consider on lightweight parts.

Low mass bolt carriers were not developed to shave weight off the overall rifle. They were developed to reduce reciprocating mass and secondary recoil in race guns. They do that very well but they must be paired with either a custom gas port (small) or an adjustable gas block. The mass of the carrier and the buffer paired with the amount of gas fed into the system must be balanced properly.


Low mass carriers have applications but if you plan to use one to shave weight, I would recommend penciling in an adjustable gas block or you may start seeing issues related to early unlocking.

IndianaBoy said:

You should let the guys on the PRS circuit know. I'm sure they would love to be clued in.

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Last I checked the PRS guys rarely carry their competition rifles dozens of miles in difficult terrain before firing a shot or two.
In reality pretty much all serious competition shooters of any precision discipline are already intimately familiar with the fairly trivial and well-known metallurgical principles I just explained to you. They're nothing new or out of the ordinary, just very basic common knowledge. Unless you already knew that and are pulling my leg? Just checking...

Looks like the OP has plenty of information about light weight ARs.