Does glass size matter if the optic is mounted forward in the rifle?

[matto6]

I'm trying to choose an optic for my Ruger PC Carbine. I see a lot of folks recommend the Holosun 510c for its large glass which improves field of view.

However I'll be mounting the optic on the rear of the barrel because that's where it sits the lowest. In this position the optic is around 11" from my eye.

Does the glass size even matter when the optic is that far forward? Most of my field of view will be around the optic, not through it, right? Will a 510c have any advantage over a 507c or 403c when mounted that far forward?

I would think the most important thing would be to have a thin border with as few things getting in the way as possible? I see rifle optics with knobs and battery components sticking out all over the place won't these become more of an issue as the optic is moved further forward?

 

[JFrank]

If this is what your talking about ? The optic mounts to the picatinney rail not the barrel.

 

[matto6]

If this is what your talking about ? The optic mounts to the picatinney rail not the barrel.

No, I have a different version of the rifle. I mean this.
https://createdbycay.com/products/ruger-pc-carbine-pcc-barrel-mounted-optic-rail-free-shipping

But how it's mounted is immaterial to my question. I'm asking about fact that it's 11" forward of my eye, and how this impacts the qualities of an optic that are important.

 

[Varminterror]

Moving the optic forward shrinks the FOV proportionately. Stick a smaller piece of glass farther forward, you’ll see less through it than you would see through it if closer, OR if it were a larger piece of glass. The farther forward the optic, the larger the glass needs to be to be able to maintain a favorable FOV.

 

[keyzard]

FWIW, I have the same model as the OP. I have my optic mounted to the top of the receiver and it has never lost "zero" after numerous take-down/re-assemblies.

I understand the desire to mount to the barrel to achieve maximum precision, but with the barrel tension adjustment (not sure of the correct term) set properly I don't see how the barrel could be attached with much, if any, variance.

Just my 2 cents.....

 

[Varminterror]

with the barrel tension adjustment (not sure of the correct term) set properly I don't see how the barrel could be attached with much, if any, variance.

The same way we’ve seen zero shift and drift with similar take-down designs for generations.

 

[MtnHiker]

Well it's not like a 9mm carbine is a long range shooter and the sights you refer too have a 2moa center dot. So this is not a precision gun or sighting system. Personally I would use the larger sight mounted to the reciver.

 

[Varminterror]

Well it's not like a 9mm carbine is a long range shooter and the sights you refer too have a 2moa center dot. So this is not a precision gun or sighting system.

Shifts smaller than the individual user’s standard for tolerance are still shifts, and not all shooters will have the same minimum standard for maximum error tolerance.

Personally I would use the larger sight mounted to the reciver.

Yeah, it’s ok, we’re just not compatible.

 

[MtnHiker]

Varminator,
My comments were not just about accuracy and or return to zero. I agree barrel mounted is better for return to zero. That said you do realize the OP is describing a 9mm carbine with a zero magnification non paralax reflex sight with a 2moa dot and or a +-30 to 65 moa ring. The general use of the holosun sights is quick target aquistion minute of bad guy at 10 feet to maybe 75 yards with a rig as described. The pc9s that my two buddies have are 3-5 moa shooters at 75 yards with 1-4 scopes. Additionally he will subject the sight to the heating and cooling of the barrel and these are battery operated electronic optics. Also if I understand which version he has he is talking about removing the rear sight, adding a short aluminum pic rail and mounting the reflex in it place which leaves him no backup iron sights. If he really needs better accuracy he should get a lower moa scope.

The good news is he can test it both ways as the rail is on the reciever on all models.

 

[benEzra]

I’m just a casual shooter (some local USPSA style matches, etc.) but I have become rather enamored of the little Sig Sauer ROMEO 5X optic. I wasn’t sure at first how I’d like the small 20mm lens, but I just replaced a 30mm Aimpoint knockoff with the 20mm Sig optic and I really like it. Yes, you see less field of view through the lens, but the body of the optic blocks so much less of the target and its surroundings that at least for me, overall visibility is improved. (The ROMEO 5X has a very thin body and the battery housing is underneath it rather than sticking out to the side, and the elevation and windage adjustments are flush with the body, so very little sticks out). Your results may vary, though, so if you can manage to try one on somebody else’s rifle before you buy, that’d probably be good.

If you do decide you like large glass, you absolutely can’t beat an Eotech for the view through the lens, btw. But they are pricey, and obviously the big lens makes the optic bulkier than the small-lens options.

 

[TonyAngel]

There's way too much thought going into this. We're talking about putting a red dot on top of a PCC, right? Mount it as far forward as you can on the pic rail of the receiver. I'd avoid putting it on the handguard above the barrel, unless the handguard and receiver are a one piece unit. Shoot with both eyes open. FOV through the red dot is irrelevant.

 

[Shawn Dodson]

I installed a Holosun 508T green dot onto my Ruger 9mm PCC. It's as far forward on the receiver's picatinny rail as possible. It's awesome!

The forward position of the sight gives me a wide field of view downrange. Also, it sits low so I get a proper cheek weld on the buttstock. It's natural and quick to acquire the dot.

I like smaller glass on a reflex sight. Less area for the dot to wander around.