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Posted: 8/17/2010 6:54:30 PM EDT
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I was really surprised this past weekend at the FT. Lauderdale gun show when comparing the Fit of the uppers and lowers from a few different makers of .223 AR's.
One group of guns made with Billet receivers and vy. hi-end pricing (well known brand) were not even close to one of the medium-priced Bushmasters with forged receivers? Does anybody have experience from handling many examples of many makes which set of upper-lowers would likely be tightest?. Still in research phase of first build, but I'm a real stickler for good fit and precision. Getting ready to drop about $1,700-$2,000 but I want it to be absolutely top-shelf when finished. 
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| RRA lowers have a reputation for being tighter than most. I just finished an RRA lower I purchased several years ago and it's EXTREMELY tight with my CAVARMS upper off my MKII carbine. I couldn't even shotgun the damn thing over my knee before putting better than 100rds through the combo this past weekend. I had to pull the front pin to get the receivers separated. It's starting to loosen up a bit after the range session, but is still a bitch to shotgun. |
| I just built two AR's w/aero precision upper and lowers. When pinned together there is abosultely no wiggle between the two; fit and finish are excellent! I think I paid $69 for a NIW lower and $59 NIW for the upper. Can't beat those prices in my books and since these guys actually supply these to name brand companies you know they're quality. |
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Quoted:
RRA lowers have a reputation for being tighter than most. I just finished an RRA lower I purchased several years ago and it's EXTREMELY tight with my CAVARMS upper off my MKII carbine. I couldn't even shotgun the damn thing over my knee before putting better than 100rds through the combo this past weekend. I had to pull the front pin to get the receivers separated. It's starting to loosen up a bit after the range session, but is still a bitch to shotgun. I like RRA. I won't say they are the best possible AR platform out there, but I will say I have not seen another brand that can beat the fit between the upper and lower. I like my fit tight, and that is just my preference. |
| When I put my gun together using an RRA lower and CMMG upper, there was a slight amount of play. I don't like loose guns, regardless of the name on the parts, and if it's the Flavor of the Month, or the perceived Tier rank. So I put in an accuwedge, and shimmed it up so it's tighter and got rid of the play. |
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A super tight fit is no indication of "top shelf." As far as stripped uppers and stripped lowers go, I don't really know what "top shelf" means. Seems like they are pretty much all GTG. If that is the case, then having a good fit between them is about all that is left that matters –– unless you want to add in color match. |
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A super tight fit is no indication of "top shelf." As far as stripped uppers and stripped lowers go, I don't really know what "top shelf" means. Seems like they are pretty much all GTG. If that is the case, then having a good fit between them is about all that is left that matters –– unless you want to add in color match. As long as they are in spec, that is all that matters. Tollerance range of the upper and lower would determine the fit. If you have an upper to one side of the range and a lower to the other you may get a tighter or looser fit. I hate tight uppers that need a hammer and punch to disassemble. Some people mistake this (and color match) as a sign of quality. |
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A super tight fit is no indication of "top shelf." As far as stripped uppers and stripped lowers go, I don't really know what "top shelf" means. Seems like they are pretty much all GTG. If that is the case, then having a good fit between them is about all that is left that matters –– unless you want to add in color match. As long as they are in spec, that is all that matters. Tollerance range of the upper and lower would determine the fit. If you have an upper to one side of the range and a lower to the other you may get a tighter or looser fit. I hate tight uppers that need a hammer and punch to disassemble. Some people mistake this (and color match) as a sign of quality. This ^^^ After years of being anal about upper/lower fit.......I've come to this conclusion.................."It doesnt matter. If they start out tight, they get loose "if" you use them........If they start out slightly loose, they still get looser........If they start out WAY loose, then somethings wrong (out of spec)..............Accuwedge is your friend !!.........In my case, Home Depot rubber bumpers from the drawers in the bolt isle, custom cut to fit 
Never thought I'd "ever" say this..............Better a little loose than too tight !! 
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Quoted:
RRA lowers have a reputation for being tighter than most. I just finished an RRA lower I purchased several years ago and it's EXTREMELY tight with my CAVARMS upper off my MKII carbine. I couldn't even shotgun the damn thing over my knee before putting better than 100rds through the combo this past weekend. I had to pull the front pin to get the receivers separated. It's starting to loosen up a bit after the range session, but is still a bitch to shotgun. RRA lower and Sabre Defense upper = very tight RRA lower and Stag upper = very tight Doublestar lower and almost any upper = loose Doublestar or RRA lowers with DPMS uppers (two I have tried thus far) = too tight to close. OP, If it concerns you, get the parts that are available and get an accu-wedge... or get a sun devil lower with the adjustable screw to tighten to about any upper. |
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Quoted:
I was really surprised this past weekend at the FT. Lauderdale gun show when comparing the Fit of the uppers and lowers from a few different makers of .223 AR's. One group of guns made with Billet receivers and vy. hi-end pricing (well known brand) were not even close to one of the medium-priced Bushmasters with forged receivers? Does anybody have experience from handling many examples of many makes which set of upper-lowers would likely be tightest?. Still in research phase of first build, but I'm a real stickler for good fit and precision. Getting ready to drop about $1,700-$2,000 but I want it to be absolutely top-shelf when finished. When talking about like materials, a machined-from-billet part will, at best, only be as strong as a good forging; never stronger. The tolerances will depend on the quality of the machining in both cases. There is nothing about "billet" that intrinsically makes it higher quality than forging. At best it will be as good as a forging, but there is a good chance it won't be as good as a forging in terms of strength. For example, a forged part will always have a grain structure that is forced along whichever axis of the part needs the most strength. A billet usually has a grain structure which is along the longest axis of the bar, but once it is cut up / machined, that grain structure may not follow the axis of the resulting part. Forging is the "milspec" way of making AR receivers BTW. |
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CMT (Continental Machine Tool) - mills for
Stag, *Rock River Arms*, High standard, Noveske, Century, Global tactical, CLE, S & W, MGI, Wilson Tactical, Grenadier Precision LAR- mills for LAR, Bushmaster, Ameetec, DPMS, CMMG, Double star, Fulton Armory, Spikes tactical, Grizzly JVP- mills for Double Star, LRB, Charles Daly Sabre Defense mills their own receivers I wonder who mills upper receivers for Model 1 Sales? Mine fits tight on all 9 of my various brand lowers. |
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CMT (Continental Machine Tool) - mills for Stag, *Rock River Arms*, High standard, Noveske, Century, Global tactical, CLE, S & W, MGI, Wilson Tactical, Grenadier Precision LAR- mills for LAR, Bushmaster, Ameetec, DPMS, CMMG, Double star, Fulton Armory, Spikes tactical, Grizzly JVP- mills for Double Star, LRB, Charles Daly Sabre Defense mills their own receivers I wonder who mills upper receivers for Model 1 Sales? Mine fits tight on all 9 of my various brand lowers. Do you know this info to be 100% true and 100% current as of this hour? |
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[://Wow Gents,
Lots of good information here. I didn't realize that there is not a significant increase in tolerances, strength, rigidity, etc. by going from a Forged receiver to a Machine-Cut Billet receiver. That list of who makes the different "branded" receivers was also eye-opening. I do want to get a lower that is Multi-Caliber in case I get a "Wild Hair" for a 6.5mm Grendel upper for some higher-powered variety. I guess I've learned what I needed to know from this thread. Thanks Everybody. Regarding Markham Park (for that freaky cross between the Tarantula and the Chip-Monk), I am up in Martin County (Stuart area) so I've got a couple of ranges that I can go to instead. |
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[://Wow Gents, Lots of good information here. I didn't realize that there is not a significant increase in tolerances, strength, rigidity, etc. by going from a Forged receiver to a Machine-Cut Billet receiver. That list of who makes the different "branded" receivers was also eye-opening. I do want to get a lower that is Multi-Caliber in case I get a "Wild Hair" for a 6.5mm Grendel upper for some higher-powered variety. I guess I've learned what I needed to know from this thread. Thanks Everybody. Regarding Markham Park (for that freaky cross between the Tarantula and the Chip-Monk), I am up in Martin County (Stuart area) so I've got a couple of ranges that I can go to instead. Unless it can actually be confirmed as up to date I would put to much stock into it. |
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Well can be assured Stag is milled by CMT and that LAR and Grizzly lowers are milled by LAR. It is a fact that JVP currently mills Doublestar and LRB. LAR has milled for Spikes Tactical in the past as did API. From what I hear they are milling their own lowers now.
If CMT doesn't mill RRA and S&W lowers any more, please enlighten us! I haven't heard whether Bushmaster, DPMS, CMMG or Fulton Armory have started milling their own receivers. Bring us up to date. "Lead, follow or step aside." |
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Well can be assured Stag is milled by CMT and that LAR and Grizzly lowers are milled by LAR. It is a fact that JVP currently mills Doublestar and LRB. LAR has milled for Spikes Tactical in the past as did API. From what I hear they are milling their own lowers now. If CMT doesn't mill RRA and S&W lowers any more, please enlighten us! I haven't heard whether Bushmaster, DPMS, CMMG or Fulton Armory have started milling their own receivers. Bring us up to date. "Lead, follow or step aside." Or say nothing if you don't actually know. There is nothing to "enlighten" you on. The point is most places have to sign NDAs and many places switch sources depending on certain factors. In short, most people have no way of knowing who does what for who and who buys what from where. A lot of the places that make a great deal of AR parts are small machine shops in CT and IL that you have never heard of. Stag/CMT is the obvious one as they are in the same building and the Son of the CMT owner is the Stag owner. |
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