Best M4 Lower Receiver

[zollen]

Am I correct that the major function of M4 lower receivers are for regulating the firing mode (i.e. safe, semi, full..etc), nothing more. M4 receivers are the least important part of an AR. M4 uppers (the most important part) regulate the power of shots and the qualities of the shots.

[Hmac]

If you consider the core of the rifle to be lower, upper, and barrel, then there's some truth to that, but I wouldn't take that to imply that one could universally pick up any old receiver. Price variations are often closely related to the degree of quality assurance applied before a rifle mfgr lets it out the door. Some companies are more rigid in the adherence to the specs than others, and as you'd expect the more receivers they throw away because they don't pass muster, the more expensive are the ones they DO sell. An out of spec lower might result in magazines not dropping easily, problems with the bolt catch function, issues with FC pins, clean fit with an upper, etc.

I had a conversation with Greg Sullivan (http://www.slr15rifles.com/Default.asp) about this this past summer. He had some very interesting experiences to relate regarding his struggles over the years to get consistently good quality receivers in building his rifles - largely related to accuracy of the CNC program files that many of the companies use (he machines his own, now). I came away from that conversation with the belief that all lower receivers are most definitely NOT created equal.

[TehLlama]

They can cause some rather beguiling issues if they're out of spec, but given the large number of quality forged examples - focus on one of those that comes with a quality LPK, and work from there. There are quite a few parts that have to meet a rather exact spec in order for the rifle to work as designed, so it actually has quite a few functions, but that's not to say that paying twice as much for some buys you a whole lot more (*unless you're a lefty looking at an SR15 IWS or something)

[zollen]

I am planning to get the BCM lower receiver. They are pretty good I think.

[Quentin]

BCM is a great choice for a lower. And of course for the upper as well.

To appreciate how important it is for a lower to be "in spec" buy an 80% lower and try to finish that last 20%. Not so easy, and you can see how important it is to buy a good lower. (Yeah, I have one and still haven't finished it. [:D])

[zollen]

BCM is a great choice for a lower. And of course for the upper as well.

To appreciate how important it is for a lower to be "in spec" buy an 80% lower and try to finish that last 20%. Not so easy, and you can see how important it is to buy a good lower. (Yeah, I have one and still haven't finished it. [:D])


Here is my plan: BCM Lower, Noveske QD Plate, Geissele SSA-E trigger.

[TehLlama]

Better plan: BCM Blemished Lower, Noveske QD Plate, and Geissele SSA (or SSA-E). Works great, and for the life of me I can't find the blemish on mine. Matches my SR15 upper's finish quite well.

[rob_s]

I had a conversation with Greg Sullivan (http://www.slr15rifles.com/Default.asp) about this this past summer. He had some very interesting experiences to relate regarding his struggles over the years to get consistently good quality receivers in building his rifles - largely related to accuracy of the CNC program files that many of the companies use (he machines his own, now). I came away from that conversation with the belief that all lower receivers are most definitely NOT created equal.

Sample of one and all that...

I bought one of those lowers based on what I thought was a very good explanation from Sully. I liked what I saw, and his logic made sense. It sat for a long time in a box while I accumulated the other parts, and once I had them I built up the gun. The problem I have is that it doesn't drop even current-production Pmags free with regularity. I need to play with it some more, but I was very disappointed after all that time to finally get it together and then have the mags stick.

This isn't to say anything negative about Sully, his lowers, or anything else, but is meant simply to point out that there are no guarantees. For anyone reading this that's planning on SBRing a lower I STRONGLY suggest building it up with all of your parts first, sticking a non-NFA upper on it, and getting some testfire with it before you send off the paperwork and engrave it.

[John Hwang]

Out of all the Lowers Rainier Arms sells & builds on (which is a lot), MEGA Arms is the nicest from our experience in terms of fit and finish. That was why Rainier chose MEGA to build our own lowers.

[zollen]

Better plan: BCM Blemished Lower, Noveske QD Plate, and Geissele SSA (or SSA-E). Works great, and for the life of me I can't find the blemish on mine. Matches my SR15 upper's finish quite well.


Blemished lower would mean a used lower. Why would you prefer a used lower?

[Hatter]

Zollen,

Blemished means just that, blemished. Usually during the manufacturing process the metal or finish may obtain a slight cosmetic irregularity. This irregularity makes the part a blemished part and they are typically sold at a reduced price. The blemish is purely cosmetic. If it sacrificed the integrity of the part at all from a mechanical use or safety point the part would be scrapped without question.

It is not a used part at all. Consider it factory seconds.

[Stickman]

Blemished lower would mean a used lower. Why would you prefer a used lower?


No it doesn't.

[freebug]

If you can find one, the Magpul China Doll lower.

I'd pay for one if I could find one. That one is a keeper!

[Stickman]

If you can find one, the Magpul China Doll lower.

I'd pay for one if I could find one. That one is a keeper!

That is not a realistic option for people.

[Army Chief]

OK, I'll bite: what is it about a Magpul China Doll lower that you find so compelling?

Given all of the recent developments we've seen on the market, these old Magpul billet lowers (MPLA, MPLC) have really been outclassed, and short of the fanboy appeal, I can't think of any reason why it would make sense to opt for one of them over what is currently available.

AC

[zollen]

Agree. It seems to me these china doll lowers are nothing more than collector items.


OK, I'll bite: what is it about a Magpul China Doll lower that you find so compelling?

Given all of the recent developments we've seen on the market, these old Magpul billet lowers (MPLA, MPLC) have really been outclassed, and short of the fanboy appeal, I can't think of any reason why it would make sense to opt for one of them over what is currently available.

AC

[freebug]

The Magpul China Doll because it is what it is. It like the white Rhino. It just another Rhino, but slightly different.

I'm sure the new lowers are all much better but still.

I find it funny.

[Bob Reed]

Hello,

Being on a budget, I need to get it right the first time, so I just stick with COLT. You know, the brand that All the others are judged against.

[zollen]

Hello,

Being on a budget, I need to get it right the first time, so I just stick with COLT. You know, the brand that All the others are judged against.

How much did you pay for the Colt lower?

[Bob Reed]

Hello,

I haven't bought any lowers by their self (only complete COLT Rifles & Carbines) but if/when I do, I'll get one from Ken.

And since I'd only be satisfied with it having all Genuine COLT Parts, I'd get this one.
http://www.specializedarmament.com/products/LE6920_Lower_Receiver_Group_Complete-879-274.html

[zollen]

$599 for just a lower? That's too expensive. I could get a DSA ZM4 Upper + PCF composite Lower with less than $599


Hello,

I haven't bought any lowers by their self (only complete COLT Rifles & Carbines) but if/when I do, I'll get one from Ken.

And since I'd only be satisfied with it having all Genuine COLT Parts, I'd get this one.
http://www.specializedarmament.com/products/LE6920_Lower_Receiver_Group_Complete-879-274.html

[Bob Reed]

Hello Zollen,

After doing a quick read of your other threads & posts, I'm NOT at all surprized by your reply.

Try to find a copy of "The Chart" somewhere, and stay as close to the left-side as possible.

Happy Easter and take care.

[Stickman]

$599 for just a lower? That's too expensive. I could get a DSA ZM4 Upper + PCF composite Lower with less than $599


Your composite lower is utter garbage, you need to figure out if you want the lowest level piece of equipment or not. There are plenty of other lower receivers available on the market that are decent that are cheaper than $600. You can pick up a complete LMT lower receiver group for $330.

[Mr.Goodtimes]

$599 for just a lower? That's too expensive. I could get a DSA ZM4 Upper + PCF composite Lower with less than $599

Any you will have wasted $599 on a complete piece of shit.

[Eric]

$599 for just a lower? That's too expensive. I could get a DSA ZM4 Upper + PCF composite Lower with less than $599
You really need to pay attention to those knowledgeable folks who have already pointed out that your preferred lower is unacceptable. Stop recommending it.

[Quentin]

zollen, you were talking about a BCM lower a while back and now consider a Plumcrazy?

May I remind you of the title of your thread? ...Best M4 Lower Receiver

[zollen]

zollen, you were talking about a BCM lower a while back and now consider a Plumcrazy?

May I remind you of the title of your thread? ...Best M4 Lower Receiver

You are correct. I love BCM lowers. It was my first choice, but they are currently having a hugh backlog and stop accepting new orders temporary. I have no choice but to look elsewhere.

[zollen]

You really need to pay attention to those knowledgeable folks who have already pointed out that your preferred lower is unacceptable. Stop recommending it.

I do. I do. I realize I have a lot to learn.

[Stickman]

I do. I do. I realize I have a lot to learn.

As long as you know that, I think its great that you are asking questions. You aren't being a smartass or anything, and I don't think anyone here wants to see you spend money on junk that we know would come back to bite you down the road.

What complete lower receiver groups do you like, and what is a realistic price for you to spend?

[zollen]

As long as you know that, I think its great that you are asking questions. You aren't being a smartass or anything, and I don't think anyone here wants to see you spend money on junk that we know would come back to bite you down the road.

What complete lower receiver groups do you like, and what is a realistic price for you to spend?

hopefully below $300

[Bob Reed]

You are correct. I love BCM lowers. It was my first choice, but they are currently having a hugh backlog and stop accepting new orders temporary. I have no choice but to look elsewhere.
Zollen - BCM's website say's they'll start taking orders again in Early May, heck man, your only looking at a 2-3 weeks wait time!

Why not just hold off and get the lower that you really want?

[TripleBravo]

I agree with the above, Zollen. Order the BCM and live happily-ever-after.[:)]

[TripleBravo]

AND...if you're looking for a decent deal on a quality lower receiver, check this out: http://www.rainierarms.com/?page=shop/detail&product_id=1462

Then talk to Rainier Arms about building the lower up for you so that it's complete. I bet you can come in close to or under your $300 mark.

[exedotbat]

While I don't have extensive experience with the AR Platform, I have built 3 AR's from stripped lowers. Based on what I have read it seems you are in the market for a built lower, but I think you might be better off getting a stripped lower. Since you are new, the process of putting one together will help you understand how this weapon platform works. That being said I think there a many options for quality lowers out there that are readily available. For the price riflegear.com usually have spikes tactical lowers on sale for around 99.00, however I would also check out rainierarms.com and look at their own lower which is manufactured by mega arms for rainier. I have used both, and they have produced great final products. This will also give you the ability to change out lower components without having to buy twice. If you do some smart shopping, you can build up a lower for just under 300.00, and have exactly what you want.

If you plan on spending a little more for something like a two stage trigger, I would suggest the JP lower parts kit (without trigger assembly), and a rock river 2 stage trigger. This combo is my favorite without breaking the bank. (You can get this combo for the best price at riflegear.com)

The following is a list of my go to sites for obtaining parts.
www.rainierarms.com
www.riflegear.com
www.bravocompanyusa.com
www.pkfirearms.com
www.stagarms.com

[UrbanPioneer]

Zollen, I'll share two pieces of useful information with you:

1 - Palmetto State Armory sells a complete lower for 299 << http://palmettostatearmory.com/1619.php >> It has magpul furniture already installed on it, is put together right, and includes a PMag. This will likely need to be shipped to a local gun store for you to pick it up from. There are instructions on PSA's website regarding what is required to get the firearm shipped to a gun store.

2 - Lurk More.

[freebug]

@Zollen.

One thing to keep in mind is that your local FFL/Gunstore will charge you a fee for bringing in the lower receiver. It could be up to $100 or a hefty % of the cost of the part/gun.

In my experience, the local gun stores rip you off on any FFL transfer because they don't want you to buy from someone else. If anyone knows of a N. Cal/SF Bay area FFL that doesn't try to screw you, let me know. It sucks when you see lowers on-line for $99 and then the FFL fee from the store is $100. Of course they do sell the Spike's for $124........ But its not what you wanted. Needless to say anything more.

Anyway, the cheapest route maybe to:
1 - Purchase the stripped lower at your local gun store
2 - Source all parts from Palmetto / Brownell's, etc...

This is what I did for my 2nd build. Some of the stores here refuse to carry AR parts and others jack up all the prices by more than $20. So, for me, I got the lower locally and everything else on line.

I found Palmetto to have great deals on Magpul grip + Lower parts kit.

Another place is CalsSportingArmory (http://www.calssportingarmory.com/). They have the Magpul CTR for $77 compared to $96 at other places. They do charge a small handling fee but it ends up cheaper than anywhere else online.

The great thing is it ends up feeling like Christmas because every day another box comes. :o

[Hmac]

@Zollen.

One thing to keep in mind is that your local FFL/Gunstore will charge you a fee for bringing in the lower receiver.

IIRC, Zollen is from Canada.

[Stickman]

IIRC, Zollen is from Canada.


In that case, life just got ugly for him, and he does not enjoy the same choices most of us do.

[223nbecker45]

Freebug check out golden state tactical. He's in sac and transfers for real cheap. Great guy.

[TehLlama]

If you plan on spending a little more for something like a two stage trigger, I would suggest the JP lower parts kit (without trigger assembly), and a rock river 2 stage trigger. This combo is my favorite without breaking the bank. (You can get this combo for the best price at riflegear.com)


I would disagree on this - going with a different LPK such as the G&R (saves money omitting a trigger and pistol grip) is enough of a margin to get a quality two stage trigger (a use GSSA) over a junk trigger like the RRA NM2 unit. The RRA is great for varmint shooting, but if trying to make a rifle that will see some high round count, the RRA won't be adequate.

[zollen]

Removed by Eric.

[freebug]

@223nbecker45. Hey, many thanks! Golden State Tactical looks like a winner. I'll be giving them a call to verify. But their Spike's lower is already such a great deal. The only bad part, $50 in savings on the receiver is spent on GAS up to order and to pickup. So, I'll have to save up and do it all at once!