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AR Mounts- What am I missing here?

vinniedelpino

vinniedelpino

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    • Sep 27, 2020
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    First, let me start by saying I'm about 1/3 of the way through a bottle of Irish whiskey, so if I'm making an ass of myself blame the booze. I'm a lightweight now.

    I've never come across an AR mount that's low enough to get a good cheek weld with a 1-x optic. I'm always too low to get a good sight picture unless I butt the stock up against my jaw. Also, with the eye relief on most modern, decent quality scopes I don't get why there's so much offset in most mounts. I feel like I'd be better off with a lower height set of rings with maybe a tiny bit of offset on the front ring only. Does this exist?

    Is the bone structure in my face all jacked up? Or is this a common issue? My long range precision rig is perfect with low rings and a 56mm objective. I want the same thing on my semi's but I'm having a hard time figuring out what works. I'm thinking about buying a delta optical 1-6x on koshkin's recommendation and I want to get this issue squared away before I commit to another LPVO. Otherwise I'll opt for an aimpoint.

    Am I better off adding a riser to my stock or is there a better mounting solution out there? I'm a cheap SOB, but this is a big issue that I need to address, so I'm willing to drop some coin if there's a better solution to my problem.
     
    You're not wrong. On some of my ARs I've set up the scope with a 20 moa riser and a set of low rings; that works a little better for me.

    Of course some AR15 mounts are lower than others, but it can be hard to find the info. I did find a lower one at one point, but forget now what it was.

    As you pointed out, with certain scopes (and especially on longer 308 receivers) you can often get away with straight rings directly on the receiver with no need for a cantilever.
     
    They (.mil) standardized the sight radius at a high number like 1.5 IIRC

    [someone correct me if I'm wrong]
     
    vinniedelpino said:
    First, let me start by saying I'm about 1/3 of the way through a bottle of Irish whiskey, so if I'm making an ass of myself blame the booze. I'm a lightweight now.

    I've never come across an AR mount that's low enough to get a good cheek weld with a 1-x optic. I'm always too low to get a good sight picture unless I butt the stock up against my jaw. Also, with the eye relief on most modern, decent quality scopes I don't get why there's so much offset in most mounts. I feel like I'd be better off with a lower height set of rings with maybe a tiny bit of offset on the front ring only. Does this exist?

    Is the bone structure in my face all jacked up? Or is this a common issue? My long range precision rig is perfect with low rings and a 56mm objective. I want the same thing on my semi's but I'm having a hard time figuring out what works. I'm thinking about buying a delta optical 1-6x on koshkin's recommendation and I want to get this issue squared away before I commit to another LPVO. Otherwise I'll opt for an aimpoint.

    Am I better off adding a riser to my stock or is there a better mounting solution out there? I'm a cheap SOB, but this is a big issue that I need to address, so I'm willing to drop some coin if there's a better solution to my problem.
    Click to expand...

    I can’t help with the rings, but this is one of the two venders state side and he is only asking 625 with free shipping. I have also been thinking about ordering one.

     
    1.5" is indeed "the standard", and I agree that it's too high for my liking. Both Badger and Nightforce make one-piece mounts with lower height (30mm only in the case of NF, but Badger gives ya lower options in 34mm as well).

    bigjake83 said:
    Why not just get a adjustable stock?
    Click to expand...

    Because most of 'em suck - the front edge of the cheek riser sits way back to clear the charging handle (particularly in the case of large-frame ARs), so my face rests on an uncomfortable corner. Oh, and they tend to weigh a shit-ton. I've got a B5 stock that came with a used chassis that I purchased in the PX; it's collecting dust for the above reasons.
     
    I can’t help with the rings, but this is one of the two venders state side and he is only asking 625 with free shipping. I have also been thinking about ordering one.

    [/QUOTE]

    That's exactly where I'm planning on ordering from. The other US vendor is about $100 more, I believe.
     
    If you run a magpul CTR, you can buy various size risers that give you the right fit. A lot of guys use these with the high mounts
     
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    Warne XSkel and dnz I believe are a tad shorter than 1.5”
     
    Avonac said:
    If you run a magpul CTR, you can buy various size risers that give you the right fit. A lot of guys use these with the high mounts
    Click to expand...

    The Magpul CTR risers were made for AKs and shotguns, if you use them on an actual AR they block the travel of the charging handle and render the gun inoperable.

    The Larue RISR telescopes and works on an AR. I used two CTRs at my old job, one with a RISR for everyday use and one without if I had to wear a pro mask. They’re great.
     
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    Why cantilever mounts? Because there is still this crazy antiquated concept that your nose is supposed to touch the charging handle. To abide by this bit of tripe, and get proper eye relief with a modern optic, the optic has to be mounted way forward on the rifle.
     
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    It may be sacrilege, but look at the UTG Accu-Sync rings. For a 30mm tube they have 18/22mm heights. I think you will find they are an amazing value and built surprisingly well. I have a big 3-18x50 scope on one of my AR10s and -0- issues.
     
    I’ve got a Larue RISR. They’re great ok. They do give you about 1/2 inch of additional cheek height, but they are pretty heavy. If you run the gun with the stock all the way out, they do nothing and you might as well just use a Magpul cheek riser. If you do run the with the stock partially collapsed, you can use the charging handle with the RISR, but it adds a non trivial amount of resistance to the charging operation.

    With my PRS stock properly adjusted for length of pull, and my optic mounted for proper eye relief, my cheek rests neatly on the cheek riser of the stock. To save weight, look at the Luth AR MBA stocks. They have stocks for both rifle and carbine extensions.
     
    Because most of 'em suck - the front edge of the cheek riser sits way back to clear the charging handle (particularly in the case of large-frame ARs), so my face rests on an uncomfortable corner. Oh, and they tend to weigh a shit-ton. I've got a B5 stock that came with a used chassis that I purchased in the PX; it's collecting dust for the above reasons.
    Click to expand...

    You do realize that touching your nose to the charging handle was only taught to utilize the ACOG that has a 1.5" eye relief.

    And there is absolutely no reason to have your head that far forward on a scoped rifle.
     
    Last edited:
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    bigjake83 said:
    You do realize that touching your nose the charger anything was only taught to utilize the ACOG that has a 1.5" eye relief.

    And there is absolutely no reason to have your head that far forward on a scoped rifle.
    Click to expand...
    Not to stir the pot, but nose on the charging handle was taught to army grunts way back in the 90s when the acog wasn’t around. If not mistaken, it was used a quick reference to make sure the shooter had the same, or close to the same head placement on rifle.
     
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    Regardless of the reason which generation was taught to put their nose to the charging handle for whatever reason, it's still not how you properly set up a Scoped rifle.

    The A1 Stock is 12.75" LOP. The A2 is 13.5" which naturally allows you to have your head further forward than most. It's a generic one-size-fits-all Grunt Proof way of teaching a style of marksmanship utilizing the issued gear the best way you can.

    90% of the time when people bitch about adjustable stocks It's because they don't know how to set up their length of pull or proper eye relief. And the other 10% is usually fucked up individuals with giraffe necks and t-rex arms.

    A picture is worth a thousand words.........
    Placement-1.jpg
     
    Last edited:
    Just an option to consider...American Defense makes a variation of their Recon mounts in a SL (Super Low) configuration. I know, split rings are problematic, but on a LPVO it should be fine if you mount it carefully.

    Do you know what mounting height you’re trying to achieve? As you suggested you may be just as well to order a good set of rings at the proper height.
     
    IMHO, current mounts make sense in the context for which they were derived, but worth thinking about whether that applies to the OP...As far as I understand it, these are the origin of AR mount geometry.

    1) NV gear and later daylight optic has now been standardized on 1.5in sight axis
    2) The short LOP on AR means you are "face forward" when the butstock in in the shoulder pocket
    3) Face forward means optic forward
    4) Optic forward means off the receiver with trad rings

    If you don't need 1-4, because you have no NV requiremet, have no need for face forward b/c you have correct LOP and long eye relieve optic, etc, and/or have an optic which can be mounted without splitting the reciever/monolithic rail, etc...you can skip all of this discussion and use whatever you want :)

    If you are military/leo procurement and have to get a bunch of people using standarized gear, its maybe a different story.
     
    ma smith said:
    IMHO, current mounts make sense in the context for which they were derived, but worth thinking about whether that applies to the OP...As far as I understand it, these are the origin of AR mount geometry.

    1) NV gear and later daylight optic has now been standardized on 1.5in sight axis
    2) The short LOP on AR means you are "face forward" when the butstock in in the shoulder pocket
    3) Face forward means optic forward
    4) Optic forward means off the receiver with trad rings

    If you don't need 1-4, because you have no NV requiremet, have no need for face forward b/c you have correct LOP and long eye relieve optic, etc, and/or have an optic which can be mounted without splitting the reciever/monolithic rail, etc...you can skip all of this discussion and use whatever you want :)

    If you are military/leo procurement and have to get a bunch of people using standarized gear, its maybe a different story.
    Click to expand...

    I'm a CPA... something like Ben Affleck in "The Accountant" except my autism hasn't been formally diagnosed yet and I'm not nearly as badass. No NV stuff on the gun or LEO/Mil issues here. I just want to be able to shoulder to my rifle, establish my cheek weld like I would with my chassis rifle and have a perfect sight picture with a lpvo. My cheek weld is more like a chin weld and it's driving me nuts. I'd venture to guess that 95%+ of ARs sold to the public will never see night vision, and at least half of ARs with lpvo's don't fit the user correctly whether they realize it or not. I'm really not that OCD.

    I think I'm going to follow BigJake's lead and rig something up.
     
    vinniedelpino said:
    I've never come across an AR mount that's low enough to get a good cheek weld with a 1-x optic. I'm always too low to get a good sight picture unless I butt the stock up against my jaw.
    Click to expand...



    The M16/M16A1/M16A2/M16A4 were designed so that the average sized soldier would have a good stock-weld when shooting with the fixed buttstock and the standard front-sight tower with the appropriate front-sight post. When my 20” barreled AR-15s that have the standard A1/A2 front-sight tower are zeroed using an A2 front-sight post, the top of the A2 front-sight post is approximately 2.63” above the centerline of the bore.

    Having actually measured the height of the top of the picatinny rail of a flat-top upper receiver above the bore-line of the upper receiver (and hence the bore-line of the barrel) on quite a few flat-top upper receivers from companies such as Colt, Bravo Company and Larue, I’ve found this measurement to average approximately 1.212”. This means that the distance of the top of the front-sight post above the top of the picatinny rail on a flat-tup upper receiver is approximately 1.418”. The majority of scope mounts intended for use on flat-top AR-15s place the centerline of the optic at a height that is greater than 1.418”.

    Companies that manufacture mounts/rings for the flat-top AR-15 that are a true “absolute” co-witness will have mounts that place the centerline of the optic approximately 1.418” above the top of the picatinny rail of the flat-top receiver. One example is the Geissele absolute co-witness mount for the Aimpoint T1; it places the centerline of the optic 1.41” above the top of the picatinny rail. Another example is the Scalar Works absolute co-witness mount for the Aimpoint T2; it places the centerline of the optic 1.42” above the top of the picatinny rail.

    If you want a scope mount or rings that give you the same stock-weld as the fixed sights on an M16, you’ll need a mount (or rings with a riser) that place the centerline of the optic approximately 1.41” above the top of the picatinny rail of the flat-top receiver. I’ve used the GG&G picatinny riser in conjunction with low rings to put the centerline of the optic at approximately 1.41” above the top of the picatinny rail of the flat-top receiver.







    ....
     
    Last edited:
    ma smith said:
    They (.mil) standardized the sight radius at a high number like 1.5 IIRC

    [someone correct me if I'm wrong]
    Click to expand...


    I don’t think you understand the meaning of the term “sight radius.” The sight radius of an M16A2 is approximately 20”.

    ...
     
    hlee said:
    Why cantilever mounts? Because there is still this crazy antiquated concept that your nose is supposed to touch the charging handle. To abide by this bit of tripe, and get proper eye relief with a modern optic, the optic has to be mounted way forward on the rifle.
    Click to expand...

    So you have your scope sitting back where you have no top-access to the charging handle, and have to pull it from the side only? This is one of the problems I run into with non-cantilever mounts; I can't pull the handle effectively if the scope is blocking the path.

    Secondly, I don't shoot NTCH, my stock is fully extended. With proper eye relief on most scopes (3.5") this means the scope eyepiece is just above the back of the receiver. You can't do this without a cantilever mount in most optics on an AR15 if it's not a monolith rail model. You can't get a good cheek weld if you just drop your head at the back of the stock if you have a neck. I have a neck.

    Here's the setup I had prior to selling the Vortex; Any further back and 1) eye relief would be wrong and 2) charging handle access is blocked except from the side:

    IMG_2922.jpeg
     
    Molon said:
    I don’t think you understand the meaning of the term “sight radius.” ...
    Click to expand...

    An sight's radius above the pic rail is also the definiton of ring height. (y)

    [sorry for any confusion]
     
    @ormandj Everybody has the same problem with the scope, unless your scope has some crazy long eye relief. Buy a Ambi Charging handle, the Radian Weapons Raptor Ambidextrous Charging Handle works perfectly. Have you properly measured your Length of Pull?? It's the distance from the pad of your trigger finger to the crook of your arm, Set your LOP by applying that measurement from the trigger shoe to the rear of the stock.

    This is usually where the light bulb turns on for most people, they find out that once you properly measure and set your length of pull. You'll find out the charging handle usually has plenty of room to be pulled to the rear to lock the bolt back when using a stock with an adjustable cheek height.

    Measure and set your length of pull. Close your eyes, get behind the rifle and place the stock into the pocket of your shoulder. While keeping your eyes closed get your cheek weld on the stock in it's NATURAL AND COMFORTABLE RELAXED POSITION, You should not feel cramped or like you're straining your neck. Now open your eyes and slide the scope to the rear until you have a clear edge to edge sight picture, once you acquire this that is where your scope should live. Everybody's going to be slightly different.

    This is how far back my GEN2 Razor lives because of its 3.5" Eye Relief 14.5 LOP and I have no neck.


    IMG_20201029_232218090.jpg
     
    Last edited:
    On my latest gas gun build, I used (don't laugh) an ar stoner brand 1 piece mount from midway. 20 moa elevation built in, 1.43" mount height. Fits a scope with 30mm tube and 50mm objective perfectly. I've so far put 400+ rnds through the weapon with nary an issue.
     
    bigjake83 said:
    @ormandj Everybody has the same problem with the scope, unless your scope has some crazy long eye relief. Buy a Ambi Charging handle, the Radian Weapons Raptor Ambidextrous Charging Handle works perfectly. Have you properly measured your Length of Pull?? It's the distance from the pad of your trigger finger to the crook of your arm, Set your LOP by applying that measurement from the trigger shoe to the rear of the stock.

    This is usually where the light bulb turns on for most people, they find out that once you properly measure and set your length of pull. You'll find out the charging handle usually has plenty of room to be pulled to the rear to lock the bolt back when using a stock with an adjustable cheek height.

    Measure and set your length of pull. Close your eyes, get behind the rifle and place the stock into the pocket of your shoulder. While keeping your eyes closed get your cheek weld on the stock in it's NATURAL AND COMFORTABLE RELAXED POSITION, You should not feel cramped or like you're straining your neck. Now open your eyes and slide the scope to the rear until you have a clear edge to edge sight picture, once you acquire this that is where your scope should live. Everybody's going to be slightly different.

    This is how far back my GEN2 Razor lives because of its 3.5" Eye Relief 14.5 LOP and I have no neck.


    View attachment 7475838
    Click to expand...
    What you just wrote is exactly what was taught during the first day of my first rifle class. And I also run the Luth stock as well. Great info.
     
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    ormandj said:
    So you have your scope sitting back where you have no top-access to the charging handle, and have to pull it from the side only? This is one of the problems I run into with non-cantilever mounts; I can't pull the handle effectively if the scope is blocking the path.

    Secondly, I don't shoot NTCH, my stock is fully extended. With proper eye relief on most scopes (3.5") this means the scope eyepiece is just above the back of the receiver. You can't do this without a cantilever mount in most optics on an AR15 if it's not a monolith rail model. You can't get a good cheek weld if you just drop your head at the back of the stock if you have a neck. I have a neck.

    Here's the setup I had prior to selling the Vortex; Any further back and 1) eye relief would be wrong and 2) charging handle access is blocked except from the side:

    View attachment 7475762
    Click to expand...
    Yeah, my guns are set up as below- at least as far as scope position is concerned. For optimum length of pull first, then for eye relief. The scope sits where the scope sits. I’ve never had an issue with the charging handle, though I do have the benefit of being right handed. A BCM gunfighter with medium latch, or even better the BCM 3x3 ambi latch, makes charging from one side easy. As for neck, I give ET a run for his money...
    F78A87DE-D456-4A84-B091-D7112616FA5F.jpeg
     
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    bigjake83 said:
    @ormandj Everybody has the same problem with the scope, unless your scope has some crazy long eye relief. Buy a Ambi Charging handle, the Radian Weapons Raptor Ambidextrous Charging Handle works perfectly. Have you properly measured your Length of Pull?? It's the distance from the pad of your trigger finger to the crook of your arm, Set your LOP by applying that measurement from the trigger shoe to the rear of the stock.

    This is usually where the light bulb turns on for most people, they find out that once you properly measure and set your length of pull. You'll find out the charging handle usually has plenty of room to be pulled to the rear to lock the bolt back when using a stock with an adjustable cheek height.

    Measure and set your length of pull. Close your eyes, get behind the rifle and place the stock into the pocket of your shoulder. While keeping your eyes closed get your cheek weld on the stock in it's NATURAL AND COMFORTABLE RELAXED POSITION, You should not feel cramped or like you're straining your neck. Now open your eyes and slide the scope to the rear until you have a clear edge to edge sight picture, once you acquire this that is where your scope should live. Everybody's going to be slightly different.

    This is how far back my GEN2 Razor lives because of its 3.5" Eye Relief 14.5 LOP and I have no neck.


    View attachment 7475838
    Click to expand...

    You do realize you described exactly what I explained and what I have done. My LOP is set due to my arm length, and my scope is mounted for eye relief first and foremost. If I had no neck, as I mentioned, it would look exactly like yours, an inch or two back. My LOP and eye relief on my scope almost exactly match yours, except to get a proper cheek weld with my neck length my head sits a few inches forward. Most people have shorter arms than I or you do, 14.5 is a fairly long LOP for the average shooter, and thus for an average person with a neck and a more normal LOP, cantilever mounts are a must with modern higher eye relief optics on non-monolithic ar15s, as you don’t want to bridge the receiver to handguard junction with a mount.

    Also, I do have an ambidextrous Giessle handle on my rifle, you can probably see it if you zoom in. I still prefer to maintain top access to rack back with a full grip if needed, before going to pogo.
     
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    bigjake83 said:
    You do realize that touching your nose to the charging handle was only taught to utilize the ACOG that has a 1.5" eye relief.

    And there is absolutely no reason to have your head that far forward on a scoped rifle.
    Click to expand...

    Glad to hear that you can diagnose a complex ergonomics problem without so much as a single picture or set of basic measurements. That's impressive!

    :cautious:
     
    It sure looks and sounds like some of you are shooting with the rifle at an angle to your body, rather than squared up behind it. That makes more difference to scope position than the vast majority of body type differences, but nobody's mentioned it at all. (and maybe some of you don't realize you're at an angle to the rifle, that seems pretty common too.)

    I kind of chuckle at the LOP arguments; some guys here are way too serious about their way being the only way. It's not a bolt action with limited range of scope positioning, and setting the stock all the way back isn't the only workable method. Just get the scope adjusted right for the stock position you use; there's plenty of room on an AR. Personally I lock the stock down in the mid range, which gives me room to adjust it forward or back as needed for heavy clothing, different shooters, etc.

    Also - the complaints about only being able to grab the charging handle from the side are dumb. It works, so do it. You don't have to grab the charging handle from the top. Proper scope positioning is more important.
     
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    Here...mark 12 mod 0 with A1 butstock and using rings...
    illustrates every point being made in this thread

    Mk12_Mod0_Profile.jpg
     
    Notice the BUIS, the fwd optic, and the front ring placement bridging the receiver/handguard gap...
     
    bigjake83 said:
    And the only reason that's possible is because it's using a PRI Monolithic Top Rail Riser, and a A1 Stock....
    Click to expand...

    Exactly...so if somebody asks "why is this AR's optic mounted tall and forward"...the answer is... (y) (pic related)
     
    I found 3m rubber sticky pads on amazon for $5 that were 1/8" thick. I stuck two of them together, cut to shape and slapped them on the stock. I don't know what kind of mess it's going to make when I try to get them off, but they seam sticky enough that I'm not worry about them falling off and they're the perfect height for me.

    Slick enough not to pull at the beard either.
     
    hlee said:
    Yeah, my guns are set up as below- at least as far as scope position is concerned. For optimum length of pull first, then for eye relief. The scope sits where the scope sits. I’ve never had an issue with the charging handle, though I do have the benefit of being right handed. A BCM gunfighter with medium latch, or even better the BCM 3x3 ambi latch, makes charging from one side easy. As for neck, I give ET a run for his money...
    View attachment 7475892
    Click to expand...
    What stock are you running on this fine weapon?
     
    Majja said:
    What stock are you running on this fine weapon?
    Click to expand...
    It’s the factory stock from a Ruger precision rifle. I really didn’t like it and replaced it with a Magpul PRs on my RPR. But, waste not, want not, I threw it in a drawer. Being cheap, and having found a solution for my major gripe (razor sharp edges on the bottom-resolved with a 3D printed bag rider I found in the giant RPR thread), I put it on this new ar build. The jury is still out on whether it gets replaced with a PRS. But, the price was right so what the hell.
     
    Thanks I dig the reusing of stuff i already have to some extent. You might as well try it.
     
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