Ceratac AR308

[sluggo1987`]

Has anyone on here had any luck with Ceratac's AR308 kit?

Ceratac 308

I want to build a .308 for hunting and target shooting, no high-precision super-long-range sniping need be done. However, it appears to be the Armalite configuration, which from what I've read may be problematic. Would it be a problem? It seems hard to beat for the price, but if I'd end up spending out the wazoo for repairs and upgrades, maybe a DPMS would be better.

[edgecrusher]

This is the first I’ve seen it posted. Just a few things I’d be concerned with.

To many references to Mil spec and Gi parts for my liking. 308AR’s have no standard, and many ar15 parts simply may not work.

It has an Armalite cut on the receiver but accepts pmags, so it could be modeled after the A model. No big deal there. Not sure what you read that makes Armalite problematic, if I was looking to buy a complete rifle for under $1000 that would be my first place to start followed by Aero Precision.

Do you have the tools to finish the lower? Have done them before?

 

Also remember you get what you pay for,  a quality 308 AR is not going to be cheap. Ask the guys struggling with PSA rifles......

 

?

[sluggo1987`]

Thanks  for the reply.

I've done an AR15 build, so I have the tools and the ability to put together a lower. For the price I figured that even if it absolutely sucks, I could upgrade the barrel and trigger group and still come out way ahead, but that was before I learned about the platform differences. What I meant by problematic is that from what I've read, it seems like there's no interchangeability between DPMS and Armalite, it might be hard/expensive to get Armalite parts or to upgrade it to any degree beyond the base quality, and of course if Armalite goes out of business or switches to DPMS, the Armalite platform might end up being unsupported. If that's not a problem, then I'd be willing to give it a shot, but if I'd end up having to spend a ton of money I'd rather just start with Aero or another DPMS brand off the bat.

[edgecrusher]

I would try to contact them with your specific questions. They do not specify any specific parts so it may be their receiver cut of choice.

 So you know, you can use an Armalite barrel and bcg in a DPMS frame. Or vise versa. What you can’t do is mix. Armalite and DPMS also use different thread patterns for hand guards. The Armalite recoil system is the most proven out of the box for a collapsible stock (DPMS will work too but many weird mix and match combos for generic vendors) and will work on both. Hope this clarifies some. My guess is you’ll spend 200 plus to make this kit work on top of initial purchase. That’s before you do the trigger or barrel upgrade. Is it worth the time and effort? That’s on you...

[98Z5V]

28 minutes ago, edgecrusher said:

 So you know, you can use an Armalite barrel and bcg in a DPMS frame. Or vise versa.

Yes, you certainly can. 

[shepp]

On 8/15/2018 at 9:35 PM, sluggo1987` said:

Thanks  for the reply.

I've done an AR15 build, so I have the tools and the ability to put together a lower. For the price I figured that even if it absolutely sucks, I could upgrade the barrel and trigger group and still come out way ahead, but that was before I learned about the platform differences. What I meant by problematic is that from what I've read, it seems like there's no interchangeability between DPMS and Armalite, it might be hard/expensive to get Armalite parts or to upgrade it to any degree beyond the base quality, and of course if Armalite goes out of business or switches to DPMS, the Armalite platform might end up being unsupported. If that's not a problem, then I'd be willing to give it a shot, but if I'd end up having to spend a ton of money I'd rather just start with Aero or another DPMS brand off the bat.

Welcome to the forum feel free to tell us about yourself in the intro section

[Lane]

I thought I should throw my hat in the ring here. I had been eyeballing the Ceratac kit as well until I asked them about the machining. I have built their AR-15 kits without a jig; simply following blueprints. Unfortunately the response I got in regards to the 308 kit is that it's not like anything else, and they won't provide measurements. 

All that said; they have been on sale this weekend, so I ended up buying one anyway. I DID NOT buy their jig plates (Conversion Kit) since I don't have a 5d tactical jig to attach them to. My thought was that given it comes with their upper, I should be able to measure everything very carefully to determine where the FCG should be located. The trigger has to fit under the selector and be tight in Safe, and the hammer has to hit the firing pin. Doesn't seem like rocket science to me. Furthermore; the selector detent usually runs straight up into the center of the selector hole, and the other two pins locations are referenced off of that.

I do have measurements/blueprints for DPMS and AR-10 lowers; but if what Ceratac says is really true they won't be too much help? Has anyone actually seen or built one of these? Are any of my suppositions totally off base about how the location of the FCG can be determined? I'm not entirely opposed to buying the conversion kit to get a helping hand if I really need it. But quite frankly, I think they should provide the measurements and don't want to encourage that kind of behavior on their part. Is there really a concern that some other manufacturer is going to copy the design, or did they copy something they didn't have permission for?

Any insights or further discussion would be appreciated. I honestly didn't even think to ask what type of magazines were compatible so I'll have to get in touch with them again later this week.

[98Z5V]

4 hours ago, Lane said:

the selector detent usually runs straight up into the center of the selector hole, and the other two pins locations are referenced off of that.

 Are any of my suppositions totally off base about how the location of the FCG can be determined?

That'll work, well. 

[Lane]

I appreciate the vote of confidence on that method. 

While trying to find more information about it I stumbled across a page on the 5d tactical website in regards to their jig working with the Ceratac lower. They refer to the lower as a Cerro Forge - Ruger SR-762. I assume that means if I can find an SR-762 to measure against; that would actually allow me to do a real comparison with other 308 FCG layouts.

I saw a measurement comparison between three different 308 platform "standards" in a recent thread on AR15.com while searching around. It was in reference to the reliability of 80% AR-10 builds. I don't see a reason to copy the image here since I don't know if any match up with the Ceratac kit.

Still not sure exactly when my kit will show up given it is a holiday weekend. I will be sure to report back my findings when it does. In the mean time I'll see what else I can find out about this. I haven't found a review or mention of anyone else building this particular kit; should be interesting.

[jtallen83]

8 minutes ago, Lane said:

They refer to the lower as a Cerro Forge - Ruger SR-762. I assume that means if I can find an SR-762 to measure against; that would actually allow me to do a real comparison with other 308 FCG layouts.

Early Matrix Aerospace sets were the same as Ruger SR-762's, Matrix made them for Ruger. I have one but not accurate enough tools to take the measurements. I can tell you they are their own animal. Shaped like an Armalite in the receiver cuts but not compatible at all.

[Lane]

Thanks! I found some pictures of a Matrix Aerospace SR-762 that appears to match the physical features shown in images of the Ceratac kit. No specific blueprints yet but I'm a lot less worried about that now. The pocket looks normal enough and I simply need to worry about placement of the FCG inside of it.

From what I can tell, the only variations in position are based on the distance between the pivot pin, and the selector; both of which come "finished" in the 80% lower (selector location being indicated by the detent pin hole). I should be home free if all that is in fact true. I'll be sure to take my time with this and measure everything repeatedly before I get started.

[Lane]

I have been trying to find more information about the SR-762 and found some forum discussions elsewhere dating back to 5+ years. Between all of those posts I compiled a list of what people said were compatible uppers for the real SR-762. Unfortunately I have no way to verify at the moment, but here is that list: Armalite AR10A, Larue Tactical, KAC (Knight's), LMT, Matrix Arms (they make the Ruger receivers), Genesis CNC.

Does anyone else around here have a way to check any of these? Is that really true that an AR-10A upper fits on a SR-762?  I found that listed more than once as being compatible, or maybe they only mean the distance between takedown lugs and hole size?

I actually found a crappy blueprint JPEG for the AR-10 lower when I was researching my first AR-15 build. Unfortunately I don't know for sure what version it is or anything else about it. It is very low resolution, and cutoff at the bottom where that technical information would have been found. One of the few things I can make out in the details is that it says "Proprietary and Commercial". I found it again just now with a simple Google image search for "ar10 lower receiver blueprint"; it is currently the 22nd image, 1116 x 675 pixels. While trying to finish this post I found a few .pdf files which are much more complete with the same measurements; this time for something called a KAD-10. I assume I shouldn't be posting pictures that are copyrighted or whatever.

After looking at comparison photos of AR-10A and AR-10B, I believe these prints are all for the AR-10A. Could this by why Ceratac says "it doesn't fit anything" and they won't release the measurements (because they are directly copying something proprietary)? Does anyone know if the 5d tactical jig is supposed to support the AR-10A layout, their website is very unclear? Should I be moving over to the 80% forum now or is this ok here?

My kit still hasn't shipped, though I'm not shocked since I ordered some other things too, and it seems like everyone is swamped today after the holiday weekend. I'm still expecting to see it later this week since all my other orders with them showed up in two days flat. First order of business will be comparing the lower to these blueprints. 

Quite frankly I simply don't know what I don't know. I haven't laid hands on a 308 build, much less compared all the variations. I guess I'm just talking to myself in public now... But really; thanks for all the help so far.

[98Z5V]

Several of us here have the early Matrix receiver sets.  I build mine into a .338 Federal "Pig Puncher."  That info should be in the Matrix Section. I think we talked about those receivers NOT working with an Armalite upper, but you'd have to research that section to be sure.  I can't remember the direct specifics.

At the Fall Shoot in another month-ish, I can try to mate an Armalite upper to the Matrix lower, if you can wait for that.  We'll try to shoot it, and see if it functions.  

The early Matrix receiver sets ARE the Ruger SR-762 sets.  They ARE.  Matrix changed what they offer now to the public, and they're DPMS-based now.  The original Matrix sets were 'M-762" sets, and the engraving in them was identical to the stuff you see on the "Ruger SR-762" receivers - they didn't even change the font.  Mirror image, minus the naming.

[Lane]

That all sounds good. I ordered this because, like sluggo1987; I want a very personal hunting gun. Season doesn't open for well over a month so the Fall Shoot might not be too far away. I wanted a 308 because I love the AR-15 platform, and just need some bigger bullets; AK-47s aren't quite enough either. I also just love to build, and can't seem to stop anymore.

From what I can tell; without having the kit in hand yet, it is a true SR-762 80% lower in cut. The AR-15 kits from Ceratac are also Cerro Forge 80% lowers, and pristine quality I might add. I simply don't know enough about the 308 uppers to know what else might be going on here. For all I know they actually made their own upper, and aren't lying about the fit and function of other brands. At the moment I simply don't know what to ask them specifically; since they didn't want to release their measurements or specs for the FCG layout the first time I inquired. They do say, "just ask" about compatibility, so I am trying to get a handle on all those measurements beforehand. I'd rather not be have to ask 20 questions and seem like a prick to them. So far they have been very cordial with me.

I will try to find the Matrix section you are referring to. I have been reading as much as possible here, and around the web. I really loved reading that chicken contest thread the other day. I got about half way through and though it might still be up in the air; but then you had a very worthy contender show up at the table. This place is awesome, and very specific to these builds; I hope I can hold my own one day. You are welcome to poke fun at my cheapskate mentality buying this Ceratac kit. Wait until you see my milling equipment... The finished product on the other hand. I guess you'll have to wait and see if I have the skills.

I had already figured out that the new Matrix stuff isn't the same. I didn't find many pictures of the old ones around; but one really good set was enough to compare visually. jtallen83 mentioned early Matrix; so I was watching out. Anyone have a clue when the changed over? I just found that Matrix forum area; and see 2013 posts with the old style. Seems like it wasn't all that long ago.

I still have a few more days to study up on this before the exam. I'll do my best. Thank you sir.

[98Z5V]

https://forum.308ar.com/forum/126-matrix-aerospace/

 

Hit it...

[Lane]

11 minutes ago, Lane said:

I just found that Matrix forum area; and see 2013 posts with the old style. Seems like it wasn't all that long ago.

That's what I said. I already did HIT IT. So I guess I was wrong about the year, 2015 shows the old style so far as I can tell. Still a lot of reading to do. You are all over this poop though, and I'm glad you care. Do you actually want me to post those files I have? I haven't actually read all the rules here yet. I'm more interested in the content; but so many threads... I'm not sure I will live long enough to read them all...

[survivalshop]

Seems they kinda have a " Gotcha " on that Jig system .

 

[jtallen83]

9 hours ago, Lane said:

Anyone have a clue when the changed over?

Roughly one year that I know of for sure. I can say without a doubt my AR-10B is not interchangeable, neither is my Sig 716. Fulton's 308 did not match up either. I should have my Aero M-5 set back in hand soon and will check that.

[98Z5V]

21 hours ago, Lane said:

 Do you actually want me to post those files I have?

Hell yeah - this place is all about technical information.  We get astray often, and off-track easily - but the tech data is what we're all here for. You won't violate any rules here posting any of that stuff, at all.  

[Lane]

I do believe they "think" they have me bent over a barrel on that jig system. Unfortunately for them I know how to use a ruler and will be happy to share my findings. 

I watched an Armalite YouTube video today comparing the AR-10A and AR-10B and they stated that the uppers are not compatible between the two. I also had no idea that the AR-10A version didn't come out until 2012 which leads me to some further confusion. One of these sets of blueprints is dated 2004, and another 1981. Does that mean that both are absolutely for the AR-10B style or was someone else making 308 clones that became compatible with the new AR-10A after the fact?

I would be curious to know how these prints compare to any of the listed SR-762 compatible units. I will again post below this with some unrelated prints which show comparisons between other variations. 

AR_10-1.pdf

AR_10-2.pdf

[Lane]

Here are some of the various 308 drawings I've found

308Lower.pdf

[98Z5V]

Don't get wrapped around the axle on AR-10A and AR-10B here, not with this platform. The early Matrix M-762 set are the perfect example (as are the Ruger SR-762, which is the same identical thing).  It's got the "AR-10 Cut" on the receivers, but just about nothing is "Armalite AR-10" about it.

The early Matrix (and Ruger SR-762) had a weird bolt catch, if I remember correctly, and it had weird takedown and pivot pins.  Other than that, is was straight-up DPMS-patterned.  Completely.  

Don't chase this ghost based on Armalite AR-10A and AR-10B, man. That's probably not the answer here.

BTW - those are some badass prints!!!  

[Lane]

Thanks. I tried to go back and edit that last post but it didn't work. I realized I had indeed made a few errors as I was piecing together from something I started writing last night.

That 1981 print does appear to be the real AR-10B? The other ones in the first post all seem to match some new style AR-10A cut, but beyond that I don't know what they are specifically. My burning question there is if they match the SR-762 / Matrix Aerospace old version, etc. Those two PDFs (AR_10-1 & AR_10-2) match the other image shown and have a date of 2004 if that helps narrow anything down.

Looks like my Ceratac 308 kit won't be here this week since it still hasn't shipped yet. I think I'm going to try to use one of the prints to make some plates to help hold the lower in the vise while I'm waiting. Here a shot of the set I use for AR-15s. I'll just modify the template I have to match since it doesn't seem like anyone else has published one yet. Simple, easy to make, and soft enough to give a little if things go horribly awry during the milling process while not marring the lower. It's just plywood with a paper template glued on, then ripped with an end mill to depth.

[98Z5V]

47 minutes ago, Lane said:

Thanks. I tried to go back and edit that last post but it didn't work. I realized I had indeed made a few errors as I was piecing together from something I started writing last night.

That 1981 print does appear to be the real AR-10B? That was the only "AR-10" available then, so it is indeed the B model.

The other ones in the first post all seem to match some new style AR-10A cut, but beyond that I don't know what they are specifically. My burning question there is if they match the SR-762 / Matrix Aerospace old version, etc.  They will NOT match the SR-762/Matrix pattern.

 

Those two PDFs (AR_10-1 & AR_10-2) match the other image shown and have a date of 2004 if that helps narrow anything down. The Armalite AR-10A Series wasn't introduced until 2012, so anything prior to that won't have an impact on the difference between the two.  The BASIC difference between the two is the cut of the upper receiver on the A-Series, to accomodate modern magazines.  There were a few other changes, but that's the big one.

Looks like my Ceratac 308 kit won't be here this week since it still hasn't shipped yet. I think I'm going to try to use one of the prints to make some plates to help hold the lower in the vise while I'm waiting. Here a shot of the set I use for AR-15s. I'll just modify the template I have to match since it doesn't seem like anyone else has published one yet. Simple, easy to make, and soft enough to give a little if things go horribly awry during the milling process while not marring the lower. It's just plywood with a paper template glued on, then ripped with an end mill to depth.

The fire control group pocket that you need to mill - the large-frame 308s and the small-frame AR15s, they use the exact same trigger, safety...  that basic milling will be identical to what you find on AR15 prints.  Identical.  One major difference you'll run into will be the rear takedown pin - the spring hole. On alot of the large-frames, it comes in from the bottom.  on the AR15, it comes in from the back. Otherwise, the fire control group pocket will be identical tothe milling of an AR15 80% lower.  The bolt catch area will be different, because the large-frame bolt catch is bigger, by a significant amount.

 

 

Edited September 6, 2018 by 98Z5V

[98Z5V]

Is this Ceratac kit an 80% lower, or do you have to mill EVERYTHING in it?...