Rimfire Scope on a Centerfire Rifle... is Parallax really a problem inside 150 yards?

[Bearcat1982]

Here's the possible combo...
-Leupold Rimfire 4x28 on a Ruger 44 mag carbine or M77/44...

I have a leupold rimfire arriving today for a 22mag m77/22... But Im thinking about putting it on the 44 carbine. Practical range for the 44 is probably 150 yards anyhow.

Any thoughts?

 

[gotboostvr]

Well, considering a 44mag and a 22lr, despite being opposite ends of the power spectrum, have a similar range/trajectory I think it might be a strangely good fit.

If it was a cheaper scope, I might worry about the durability, but being a quality Leupold, I'd think it'd hold up well. If not, they'll fix it up and you can resign it to an actual rimfire.

 

[Bearcat1982]

Well, considering a 44mag and a 22lr, despite being opposite ends of the power spectrum, have a similar range/trajectory I think it might be a strangely good fit.

If it was a cheaper scope, I might worry about the durability, but being a quality Leupold, I'd think it'd hold up well. If not, they'll fix it up and you can resign it to an actual rimfire.

their websites and everything I've read is their and other quality scope manufactures make their rimfire line to the same standard... durability shouldn't be an issue I don't think as well. That gun doesn't recoil much at all anyhow.

 

[Bill M.]

If you have enough eye relief.

 

[someguy2800]

Won't be an issue in this case

 

[Bearcat1982]

If you have enough eye relief.

plenty I have one on my squirrel gun. It would look right at home as well... The carbine looks just like a 10/22. In fact in the field I doubt anyone would know the difference until I hit the bang switch.

 

[Bearcat1982]

Leupold Shotgun scopes parallax is set at 75 yards, aren't they?

 

[CraigC]

Shouldn't be an issue at all.

Where I've seen parallax become a serious issue is with centerfire scopes on rimfires.

 

[Varminterror]

Parallax ONLY cares about the objective diameter and the relative distances for the field distance vs. the parallax focused distance.

Maximum Parallax Error potential in millimeters = 1/2 ((Objective diameter in millimeters) * absolute value of (Field distance - Parallax focused distance)) / (parallax focused distance)

**Note "absolute value" means the non-negative value, so if you have a 50mm focused scope and you're shooting at 25yrds, that value would be negative, but then you'd have a negative value for the distance, so it's simply 25, instead of -25

What this means:

Let's start with a 40mm rimfire scope focused at 50yrds, shot at 100yrds. 1/2 * 40 * abs(100-50) / 50 = 20mm of maximum potential error.

Comparatively, a 40mm centerfire scope focused at 100yrds, shot at 50yrds. 1/2 *40 * abs(50-100) / 100 = 10mm of maximum potential error.

Because we divide by the focus distance, as long as the difference between firing distance and focus distance is smaller than the focus distance, we end up with a factor less than 1 - so that favors that we get LESS parallax error with longer parallax settings than we would get by shooting the same offset in distance with a scope with a shorter fixed parallax.

**Also note - this formula dictates the MAXIMUM POTENTIAL parallax error. Meaning you'd have to have your head SO FAR OUT OF POSITION that you're obviously seeing shadowing and flashing in the FoV to warn you that you're out of line from the optic. AND because errors are not additive, we know we'd only ever expect to experience significantly less than that maximum - in general, I've seen most errors in ballistics tend to shrink by 75-85% in application, only contributing 1/8-1/4 of their gross opportunity to the actual results.

 

[Bearcat1982]

Parallax ONLY cares about the objective diameter and the relative distances for the field distance vs. the parallax focused distance.

Maximum Parallax Error potential in millimeters = 1/2 ((Objective diameter in millimeters) * absolute value of (Field distance - Parallax focused distance)) / (parallax focused distance)

**Note "absolute value" means the non-negative value, so if you have a 50mm focused scope and you're shooting at 25yrds, that value would be negative, but then you'd have a negative value for the distance, so it's simply 25, instead of -25

What this means:

Let's start with a 40mm rimfire scope focused at 50yrds, shot at 100yrds. 1/2 * 40 * abs(100-50) / 50 = 20mm of maximum potential error.

Comparatively, a 40mm centerfire scope focused at 100yrds, shot at 50yrds. 1/2 *40 * abs(50-100) / 100 = 10mm of maximum potential error.

Because we divide by the focus distance, as long as the difference between firing distance and focus distance is smaller than the focus distance, we end up with a factor less than 1 - so that favors that we get LESS parallax error with longer parallax settings than we would get by shooting the same offset in distance with a scope with a shorter fixed parallax.

**Also note - this formula dictates the MAXIMUM POTENTIAL parallax error. Meaning you'd have to have your head SO FAR OUT OF POSITION that you're obviously seeing shadowing and flashing in the FoV to warn you that you're out of line from the optic. AND because errors are not additive, we know we'd only ever expect to experience significantly less than that maximum - in general, I've seen most errors in ballistics tend to shrink by 75-85% in application, only contributing 1/8-1/4 of their gross opportunity to the actual results.

so what your saying is at deer vital size target we're not going to have a big problem. And inside 75 yards not a problem at all

 

[jmr40]

Parallax is how far your bullet will impact away from where the crosshairs are pointed if you don't get your eye directly in line with the scope. For most shooters, shooting most big game hunting rifles neither the rifle, nor shooter is good enough for it to be an issue. It could be enough error to cause a miss on small varmints at long range or for target shooters.

But as long as the shooter is using proper form and gets directly behind the scope it will never be an issue.

My only concern here is the ability of a rimfire scope to handle centerfire recoil. And I just don't know.

 

[Bearcat1982]

Parallax is how far your bullet will impact away from where the crosshairs are pointed if you don't get your eye directly in line with the scope. For most shooters, shooting most big game hunting rifles neither the rifle, nor shooter is good enough for it to be an issue. It could be enough error to cause a miss on small varmints at long range or for target shooters.

But as long as the shooter is using proper form and gets directly behind the scope it will never be an issue.

My only concern here is the ability of a rimfire scope to handle centerfire recoil. And I just don't know.

Leupold says their rimfire line is made to the same standards so does vortex in regards to recoil, and I would guess the others do as well. The ruger 44 carbine has very little felt recoil regardless. The 44 being pretty mild in a rifle to begin with, after cycling the bolt its pretty tame.
My rimfire rifles all had centerfire scopes until recently and i never gave it a thought. But this leupold rimfire scope that arrived today is my second.

 

[Varminterror]

so what your saying is at deer vital size target we're not going to have a big problem. And inside 75 yards not a problem at all

I’d probably be more comfortable to say - what I’m saying is that blaming a gutshot deer at 75-150 yards on parallax would seem like a pretty lame excuse to me.

I’m working on an update of this, a video with additional exploration and evidences, but here’s an infographic I put together about 11-12 years ago. The red dot at low right is a laser boresighter, present to reference that the rifle remains fixed and the point of aim isn’t moving - BUT - you can see I’m able to push the reticle around on target just by moving the camera side to side. I was able to push the reticle side to side about an inch, and using the above formula, the maximum error should be around 20mm, about .8”…

 

[DMW1116]

I put a fixed 4x Simmons rimfire scope on my 30-30 for testing cast loads and haven’t been able to talk myself into taking it off yet. These are reduced loads and match a Velocitor type 22 load for muzzle velocity. Accuracy is very good out to 100, but I can’t comment on recoil. These are greatly reduced loads from factory power 30-30.

 

[PapaG]

I think it is and anyone shooting BR50 or any other precision 22 competition would agree. For plinking or just poking at things far away, I don't have an opinion.

 

[Varminterror]

I think it is and anyone shooting BR50 or any other precision 22 competition would agree.

How many competitive rimfire shooters, in your opinion, use fixed parallax scopes?

How many competitive rimfire shooters, in your opinion, are using any "rimfire" scope?

 

[dranrab]

This is an easy to use parallax calculator.

Parallax Error Calculator - Leland-West Insurance

This quick calculator shows the amount of parallax error that may occur using a fixed-parallax scope to sight onto an object placed at a known distance.

www.lelandwest.com

 

[Oldschool shooter]

I was always under the impression that rimfire scopes couldn't hold up to the recoil of centerfire rifles. Am I the only one that didn't get the memo? Being built to the same standards may mean quality standards, but does this mean they will hold up to CF recoil?

 

[Varminterror]

This is an easy to use parallax calculator.

Parallax Error Calculator - Leland-West Insurance

This quick calculator shows the amount of parallax error that may occur using a fixed-parallax scope to sight onto an object placed at a known distance.

www.lelandwest.com

Those guys are really interesting - they've had that calculator on their site for a LONG time, and have updated it within the last several years when they changed their website so their calculator offers the table now instead of just a discrete value output. But they're a collector/luxury car insurance company... I called their office one time just to ask - why do you guys have a rifleshooting parallax calculator on your website? The answer was as pure as it gets - our ownership likes shooting, so they put it on their site a long time ago, and people seem to use it, so we keep it going.

 

[Bearcat1982]

I was always under the impression that rimfire scopes couldn't hold up to the recoil of centerfire rifles. Am I the only one that didn't get the memo? Being built to the same standards may mean quality standards, but does this mean they will hold up to CF recoil?

Leupold and vortex clearly state they will with stand the same recoil as their centerfire counterparts

 

[Bearcat1982]

I’d probably be more comfortable to say - what I’m saying is that blaming a gutshot deer at 75-150 yards on parallax would seem like a pretty lame excuse to me.

I’m working on an update of this, a video with additional exploration and evidences, but here’s an infographic I put together about 11-12 years ago. The red dot at low right is a laser boresighter, present to reference that the rifle remains fixed and the point of aim isn’t moving - BUT - you can see I’m able to push the reticle around on target just by moving the camera side to side. I was able to push the reticle side to side about an inch, and using the above formula, the maximum error should be around 20mm, about .8”…

View attachment 1188929

Very interesting and similar to what I've noticed when messing around shooting and holding my sight picture intentionally askew

 

[someguy2800]

I was always under the impression that rimfire scopes couldn't hold up to the recoil of centerfire rifles. Am I the only one that didn't get the memo? Being built to the same standards may mean quality standards, but does this mean they will hold up to CF recoil?

I’ve seen more issues with cheap centerfire scopes on rimfires than the other way around. Specifically semi auto 22’s. The bolt clacking against the front of the receiver will find the weak points

 

[DMW1116]

I’ve seen more issues with cheap centerfire scopes on rimfires than the other way around. Specifically semi auto 22’s. The bolt clacking against the front of the receiver will find the weak points

I’ll second that. It’s mostly been the rings for me. The bolt moving forward against the barrel would walk the scope off the back of the rail on my Marlin 60.

 

[lysanderxiii]

.44 would scramble the internals of a .22 scope.

.22 scopes are only made to withstand .22 recoil, even good ones.

 

[CraigC]

.44 would scramble the internals of a .22 scope.

.22 scopes are only made to withstand .22 recoil, even good ones.

That's just not true. A .44 rifle isn't that punishing but I'd put the Leupold rimfire scopes on anything.