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I have only built, or had my hands on enough parts for 6 AR's. Not all have been Grendels but the last one was,and the next two will be a .300 AAC and and another Grendel if I can get my hands on a true match grade barrel from Shilen, Saturn, or CSS (I was warned on this forum CSS would promise delivery for months, that is exactly what is happening!) I'll wait as long as needed for the Saturn and need to stop by Shilen's shop next time I go to Dallas.
Here is what I have learned for all the new builders out there, JMO, but I think many guys would probably like to know about this kind of stuff if they're like me and expect quality, and thought all parts are the same, naive that way I guess.
There is a huge difference in the quality of bolt carriers. The last one I used from a well known on-line shop was "mil-spec". The material was soft and had numerous tooling marks on the bottom which caused a noticeable lack of smoothness when cycling and firing the gun. It became apparent the material was galling even when well lubricated. The bore (hard chromed of course) for the bolt was several thousandths oversized and kept the gun from functioning reliably. Sent an email, I hope they will give me a store credit or refund, I don't want another one from them or another place that had the same problem with rough machining and soft material and poor finish.
On the other hand the BCM carrier I've had, and reluctantly parted with to fix a friends gun had no such marks and a super hard, slick surface. I'll gladly pay the extra $125.00 dollars for the next one I buy from BCM. Does anyone know what they plate/coat their BCG with?
Most may work just fine, but this kind of stuff makes me crazy on parts that should last a lifetime on a lightly used gun.
The 2 Young Manufacturing NM hard chromed carriers are also exemplary in fit and function. I'm not worried that the key is not staked, they're on hunting rifles that only see 100 rounds a year or so.
There is also much disparity in stripped uppers and lowers available from everyone it seems. The Aero precision versions I have been using are hit and miss, especially the lowers. Two of the 4 I have would not allow me to use a Timney trigger (great trigger by the way) because the pin spacing is probably off by 1000th. Some have great finishes and some show up with thin spots or bare spots on the inside. They all have less than appealing machine work at the front of the mag well, the forging line looks like it's cleaned off with a belt sander, not machined. The rear forging line is also not completely machined off, so all my lowers have grips that extend up the receiver.
They function just fine other than that so I live with it.
The uppers are generally good except for two very annoying things. The forward assist roll pin hole has a slightly off center step on the top side, everyone I have exhibits this so it much be in something with the machine code that makes them that way. Using a roll pin instead of a spring pin makes a clean install next to impossible because there is no radius for the pin to start in. A spring pin makes this job much easier (more on that in a minute.)
On the left side of Aero upper receivers where the charging handle slides over the ramp, it's not machined all the way to the end, leaving a small step on top of the ramp causing an immediate galling of metal until it finally wears down. I'll try to take a picture to show what i'm talking about on both of the issues.
The RED X upper is much better, but does not fit nearly as flush on the AERO lowers.
Barrels are no different, I'm not sure if it's the barrel extensions or the upper receivers that are the culprit, but some barrels slide in too easily and require bedding the barrels with the green loctite to make me feel better, others fit perfectly and bedding would be a waste of time. I'm going to start keeping track and measuring. The uppers and extensions are probably at extreme ends of the tolerance range to make them work with everything.
I've had exactly zero barrel nuts index properly without more torque than I like (still within spec, but 70 to 80 foot pounds is a lot.) I started using shims since I don't have access to barrel nuts machined to compensate.
All have been square and sighted in with very little windage or elevation adjustment and so far I've been lucky to have them all shoot really well for hunting type rifles.
We all know this from being on this forum, I really think it's BS barrel makers seem to have a problem cutting true Grendel chambered barrels!
The last issue with receivers is why I always try to buy uppers and lowers from the same manufacturer. Take down pin hole spacing and sizing is all over the place. You can imagine what kind of problems this causes. Some just won't play together and would not work at all unless I was willing to ream the holes, which I have never done.
The next upper and lower I invest in will be from Les Baer if available, from the info I've found they are the only ones machining the take down pin holes while the upper and lower are held together in a fixture, perfect fit every time. Anyone have experience with them?
LPK's are personal preference I suppose, but DPMS works, although pins always seem to be excessively tight.
RRA are great simply because they use spring pins which can be installed with light pressure, no chance of damaging the finish or parts.
White Oak Armory stuff is good also, and includes some spring pins.
They're all over priced for what you get! JMO ,lol.
The Noveske NSR rail is solid and the barrel nut is cool (finish on the nut sucks and the nut steel is soft, yes I used the correct size wrench) plus it's way overpriced. I'm going to try a Daniel Defense rail next or just go back to a round tube that uses a spanner type ring nut to lock in place. I really don't need a full length top rail and they are solid feeling also. The large diameter means you need to be careful opening the receiver up.
The Midwest industries SS-2 rail has first class fit and finish, but I'm not convinced a pinch type attachment will be very solid. If they made the barrel nut longer, and put some holes for hex screws to it keep is from moving, it would be perfect. I may mod mine to use at least 3 screws,
If you want a 1 hole target rifle, there's a reason they cost lots of dollars, tolerance stacking is what makes the difference between good and great, it takes time and money to spec parts that meet or exceed tiny tolerances required for the good stuff. Great Barrels are just expensive, and take a lot of time to make, no way around that.
Of course this is only my humble opinion and I welcome your experiences. Bored today so I thought I would rant some! LOL I'm by no means bashing any manufacturer mentioned, only sharing what I have experienced which is why I read these forums in the first place!
Here is what I have learned for all the new builders out there, JMO, but I think many guys would probably like to know about this kind of stuff if they're like me and expect quality, and thought all parts are the same, naive that way I guess.
There is a huge difference in the quality of bolt carriers. The last one I used from a well known on-line shop was "mil-spec". The material was soft and had numerous tooling marks on the bottom which caused a noticeable lack of smoothness when cycling and firing the gun. It became apparent the material was galling even when well lubricated. The bore (hard chromed of course) for the bolt was several thousandths oversized and kept the gun from functioning reliably. Sent an email, I hope they will give me a store credit or refund, I don't want another one from them or another place that had the same problem with rough machining and soft material and poor finish.
On the other hand the BCM carrier I've had, and reluctantly parted with to fix a friends gun had no such marks and a super hard, slick surface. I'll gladly pay the extra $125.00 dollars for the next one I buy from BCM. Does anyone know what they plate/coat their BCG with?
Most may work just fine, but this kind of stuff makes me crazy on parts that should last a lifetime on a lightly used gun.
The 2 Young Manufacturing NM hard chromed carriers are also exemplary in fit and function. I'm not worried that the key is not staked, they're on hunting rifles that only see 100 rounds a year or so.
There is also much disparity in stripped uppers and lowers available from everyone it seems. The Aero precision versions I have been using are hit and miss, especially the lowers. Two of the 4 I have would not allow me to use a Timney trigger (great trigger by the way) because the pin spacing is probably off by 1000th. Some have great finishes and some show up with thin spots or bare spots on the inside. They all have less than appealing machine work at the front of the mag well, the forging line looks like it's cleaned off with a belt sander, not machined. The rear forging line is also not completely machined off, so all my lowers have grips that extend up the receiver.
They function just fine other than that so I live with it.
The uppers are generally good except for two very annoying things. The forward assist roll pin hole has a slightly off center step on the top side, everyone I have exhibits this so it much be in something with the machine code that makes them that way. Using a roll pin instead of a spring pin makes a clean install next to impossible because there is no radius for the pin to start in. A spring pin makes this job much easier (more on that in a minute.)
On the left side of Aero upper receivers where the charging handle slides over the ramp, it's not machined all the way to the end, leaving a small step on top of the ramp causing an immediate galling of metal until it finally wears down. I'll try to take a picture to show what i'm talking about on both of the issues.
The RED X upper is much better, but does not fit nearly as flush on the AERO lowers.
Barrels are no different, I'm not sure if it's the barrel extensions or the upper receivers that are the culprit, but some barrels slide in too easily and require bedding the barrels with the green loctite to make me feel better, others fit perfectly and bedding would be a waste of time. I'm going to start keeping track and measuring. The uppers and extensions are probably at extreme ends of the tolerance range to make them work with everything.
I've had exactly zero barrel nuts index properly without more torque than I like (still within spec, but 70 to 80 foot pounds is a lot.) I started using shims since I don't have access to barrel nuts machined to compensate.
All have been square and sighted in with very little windage or elevation adjustment and so far I've been lucky to have them all shoot really well for hunting type rifles.
We all know this from being on this forum, I really think it's BS barrel makers seem to have a problem cutting true Grendel chambered barrels!
The last issue with receivers is why I always try to buy uppers and lowers from the same manufacturer. Take down pin hole spacing and sizing is all over the place. You can imagine what kind of problems this causes. Some just won't play together and would not work at all unless I was willing to ream the holes, which I have never done.
The next upper and lower I invest in will be from Les Baer if available, from the info I've found they are the only ones machining the take down pin holes while the upper and lower are held together in a fixture, perfect fit every time. Anyone have experience with them?
LPK's are personal preference I suppose, but DPMS works, although pins always seem to be excessively tight.
RRA are great simply because they use spring pins which can be installed with light pressure, no chance of damaging the finish or parts.
White Oak Armory stuff is good also, and includes some spring pins.
They're all over priced for what you get! JMO ,lol.
The Noveske NSR rail is solid and the barrel nut is cool (finish on the nut sucks and the nut steel is soft, yes I used the correct size wrench) plus it's way overpriced. I'm going to try a Daniel Defense rail next or just go back to a round tube that uses a spanner type ring nut to lock in place. I really don't need a full length top rail and they are solid feeling also. The large diameter means you need to be careful opening the receiver up.
The Midwest industries SS-2 rail has first class fit and finish, but I'm not convinced a pinch type attachment will be very solid. If they made the barrel nut longer, and put some holes for hex screws to it keep is from moving, it would be perfect. I may mod mine to use at least 3 screws,
If you want a 1 hole target rifle, there's a reason they cost lots of dollars, tolerance stacking is what makes the difference between good and great, it takes time and money to spec parts that meet or exceed tiny tolerances required for the good stuff. Great Barrels are just expensive, and take a lot of time to make, no way around that.
Of course this is only my humble opinion and I welcome your experiences. Bored today so I thought I would rant some! LOL I'm by no means bashing any manufacturer mentioned, only sharing what I have experienced which is why I read these forums in the first place!
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