Rifle Scopes Are Scope settings comparable?

[WinJim1863]

I am relatively new to scopes but moving up in magnification (old eyes, cataracts etc. Bucket list item is shooting out to/past 1,000yds). Assuming the same load should my settings be comparable? Going from a Tract Toric 4-20X50 (which I like) to the NF 7-35X56. I will mount the NF today and Zero this coming week. I will start with the same settings but the closer the two scopes are the more it will speed my NF learning curve.
Part of the reason I ask is that I have not yet found a ballistics program that matches the performance of my handload. Hornady program at 600 yds says I should be at 13.8 MOA when in fact 12.0 MOA is just right. Programs are similarly off at 200 and 400 yrs. I have wondered whether it is the program or my scope (I think Tract is reasonably good brand; their own ballistics program, with my load, matches Hornady). For info, I am shooting Ruger PR 6.5 Creedmoor, 140 gn Hornady Match HPBT and 40.5 gn H-4350. Roughly 2630 FPS so it is not a hot load but I am almost 2 MOA less drop than predicted??
Another question re my settings vs ballistics programs- My Ruger PR has a pic rail at 20 MOA. I have assumed that since I zero at 100 yd and have entered that into the programs the 20 MOA would have no effect but thought I should ask the question. Assume the 20 MOA just gives me more room for adjustment for long range.

Will appreciate your help, experience and advice, JimB

 

[patriot07]

Did you accurately measure the scope height above bore? That can make a major difference in elevation correction at distance.

 

[Glassaholic]

Hi Jim, let me attempt to answer some of your questions. Also, I would be curious to hear your thoughts on how the Tract Toric 4-20 and the NF 7-35 compare within the comparable magnifications between the two. The NF 7-35 definitely represents one of the best long range scopes out there.

In regard to your question about are the "settings" comparable, well it depends on what settings you are talking about. If you're talking about the turrets and reticle then I have to ask, are both scopes in MOA (since you list MOA in your post I'm assuming that you have MOA reticles with MOA turrets)? Assuming that both are MOA, the next thing to identify is the click amount on your turrets, Nightforce uses true .25 MOA turret clicks instead of .25" @ 100y (I think more mfr's are using .25 MOA but was worth mentioning) , according to Tract's specs they appear to also be using true .25 MOA so the turrets should be comparable between the two scopes.

Next up is your finding that your ballistic program is showing 13.8 MOA at 600 yards but your DOPE shows 12.0 MOA is what your rifle/load is actually doing. Keep in mind that while ballistic programs have gotten better over the years they are not perfect and you absolutely must true your data to match what your DOPE is telling you. Here's the thing, I've seen some recommend that you true your velocity in order to come up with the proper corrections, but I agree with Frank (@Lowlight ) in that you should true your BC and not your velocity, so adjust your BC in the ballistic app until you get the results that match your DOPE; I would also recommend you do this at multiple distances. Also, make sure that you are entering in all your atmospherics correctly and ignore the Coriolis and spin drift settings as the margin of error won't matter at the distances you're shooting.

You are correct, even though you have a 20MOA rail cant, the program doesn't care, it only cares about your zero, the canted rail simply offers more elevation to dial within your scope. It would also be good for you to identify your scope height from center of bore to center of the scope, it doesn't have to be perfectly exact but pretty close, but if you used the default in your app and let's say it was 1.5 but your scope is actually 2" C-C then that also might make a difference.

Hope some of this helps.

 

[WinJim1863]

Did you accurately measure the scope height above bore? That can make a major difference in elevation correction at distance.

Yes, have measured it a couple of times. Caliper- center of split ring on 30mm tube down to centerline of action (There is a line running along the action which is pretty well aligned with the center of the bolt

 

[WinJim1863]

Yes, have measured it a couple of times. 2.25" with Caliper- center of split ring on 30mm tube down to centerline of action (There is a line running along the action which is pretty well aligned with the center of the bolt

 

[WinJim1863]

Hi Jim, let me attempt to answer some of your questions. Also, I would be curious to hear your thoughts on how the Tract Toric 4-20 and the NF 7-35 compare within the comparable magnifications between the two. The NF 7-35 definitely represents one of the best long range scopes out there.

Bill, thanks for the response. Comparison of the two scopes- Once I have used the NF for a while I will post my thoughts of the two. Thus far, in just mounting the scope and bore sighting in my basement it seems that the NF has a more flexible eye relief. Even at about 30X I seem to have over 1/2" front to back. The Toric seems significantly less, maybe 1/8" (??) at 20X (again, not a big deal and I really like the Toric). Both have simple BDC reticles (FFP) which I like. I am shooting F Class so known distances; I twist dials and only use the BDC for wind holds (which I never guess right thus far).

In regard to your question about are the "settings" comparable, well it depends on what settings you are talking about. If you're talking about the turrets and reticle then I have to ask, are both scopes in MOA (since you list MOA in your post I'm assuming that you have MOA reticles with MOA turrets)? Assuming that both are MOA, the next thing to identify is the click amount on your turrets, Nightforce uses true .25 MOA turret clicks instead of .25" @ 100y (I think more mfr's are using .25 MOA but was worth mentioning) , according to Tract's specs they appear to also be using true .25 MOA so the turrets should be comparable between the two scopes.

You are right in saying that both scopes are MOA/MOA- turrets and reticles and turret clicks are .25

Next up is your finding that your ballistic program is showing 13.8 MOA at 600 yards but your DOPE shows 12.0 MOA is what your rifle/load is actually doing. Keep in mind that while ballistic programs have gotten better over the years they are not perfect and you absolutely must true your data to match what your DOPE is telling you. Here's the thing, I've seen some recommend that you true your velocity in order to come up with the proper corrections, but I agree with Frank (@Lowlight ) in that you should true your BC and not your velocity, so adjust your BC in the ballistic app until you get the results that match your DOPE; I would also recommend you do this at multiple distances. Also, make sure that you are entering in all your atmospherics correctly and ignore the Coriolis and spin drift settings as the margin of error won't matter at the distances you're shooting.

My workaround has been to up my FPS- While I measure 2,630 avg I input 2,800 in the programs and the results are about right. I am not into it enough to know why adjusting BCs is better than velocity but will try that too.

Bill thanks again, very helpful, JimB

You are correct, even though you have a 20MOA rail cant, the program doesn't care, it only cares about your zero, the canted rail simply offers more elevation to dial within your scope. It would also be good for you to identify your scope height from center of bore to center of the scope, it doesn't have to be perfectly exact but pretty close, but if you used the default in your app and let's say it was 1.5 but your scope is actually 2" C-C then that also might make a difference.

Hope some of this helps.

 

[WinJim1863]

Sorry, I apparently am not responding correctly and screwing up on responses. will go the resources and try to figure it out.

 

[Glassaholic]

Sorry, I apparently am not responding correctly and screwing up on responses. will go the resources and try to figure it out.

No worries, if you're trying to respond to different parts it can be tricky, I usually copy the QUOTE codes before and after each section, otherwise it comes through embedded in the original response.

 

[Glassaholic]

Bill, thanks for the response. Comparison of the two scopes- Once I have used the NF for a while I will post my thoughts of the two. Thus far, in just mounting the scope and bore sighting in my basement it seems that the NF has a more flexible eye relief. Even at about 30X I seem to have over 1/2" front to back. The Toric seems significantly less, maybe 1/8" (??) at 20X (again, not a big deal and I really like the Toric).

I'm getting a Toric for my next review of $1k scopes so I'm very curious to see how it performs compared to the rest of the pack.

Both have simple BDC reticles (FFP) which I like. I am shooting F Class so known distances; I twist dials and only use the BDC for wind holds (which I never guess right thus far).

I do not think you meant BDC (Ballistic Drop Compensation) as those reticles are typically used in SFP scopes and are designed for specific rounds and factory loads, for example, you'll find a BDC on a reticle designed for 5.56/223 and each hash mark below the main horizontal stadia will typically represent the "drop" for that cartridge at 200y, 300y, 400y and so forth; whereas, the MOAR and Toric reticles are standard MOA reticles that have hash marks at various MOA spacing like 10 MOA, 20 MOA, 30 MOA with .1 MOA hashes in between and are not based on the ballistic characteristics of any particular cartridge, these reticles are also designed to match the turrets so you can either dial elevation/wind or hold using just the reticle.

My workaround has been to up my FPS- While I measure 2,630 avg I input 2,800 in the programs and the results are about right. I am not into it enough to know why adjusting BCs is better than velocity but will try that too.

I thought that might be the case, instead of trueing your velocity, leave your velocity as is (because you're velocity is your velocity) and instead, go in and change your BC for the bullet in the ballistic app, since you are getting "better" ballistics from your DOPE vs your app I'd recommend increasing your BC. For example, you mentioned you're using the Hornady 140gr HPBT Match bullet which has a G1 BC of .580 and you said your muzzle velocity is 2630, using the Hornady App I had to adjust atmospherics to the following in order to get your 13.8 MOA adjustment at 600 yards (granted, I guessed at atmospherics but you should be using a Kestrel or other device to get the real world results):

So, you say you're changing velocity in order to correct for your DOPE; however, instead of altering velocity you should leave the velocity as is and alter your BC, in order to get 12 MOA at 600 yards I had to bump up the BC to 1.05 which is a massive leap from .580

What does this tell me, it tells me that something is way off because 13.8 to 12 MOA is too much. What are you using to measure your muzzle velocity and are you sure it's calibrated, do you have a buddy nearby who also has a chronometer? I prefer the Magnetospeed because my old Chrony would sometimes give me false positives. Are you sure you read your muzzle velocity correct? Sometimes an 8 can look like a 6 if you're not paying attention (I've done that before!) If you're certain your muzzle velocity is correct, then double check all your atmospherics, do you have a Kestrel or other device that will give you accurate atmospherics? Instead of using the online ballistics apps, do you have a smartphone that you can download an app into, most of these will use a feature called density altitude which many prefer, or better yet, possibly look into getting a Kestrel with Applied Ballistics built in and that way you can get real time atmospherics with your solution all in one.

There are other guys here on the forum who are much more knowledgeable than I so hopefully they'll chime in and might be able to help you further troubleshoot this issue, but you've given enough information to indicate something seems very wrong.

 

[WinJim1863]

Bill,
thank you for all your work. You asked about accuracy of velocity. I use a new Magnetospeed (have retired the chrony). In my ladder testing I went from 38 gr (H-4350) to 41.5 gr in 1/2 gr increments. I fired two 5 round stages at each increment so a total of 50 rounds. As I moved up in powder charge the avg velocity came up consistently 30-40 FPS for each +1/2 grain. At my selected load SDs 6.4 and ES was 9 FPS. So, with all this I think the 2630 FPS I am using is accurate.

Interesting that the workup you did shows 12 MOA at 600 yards which is right for my load but it shows 6.3 MOA at 400 yds when in fact I am at 5.0 MOA. As you say, the difference between 13.8 and 12.0 is too much. Something is goofy I just haven't figured it out yet. I am going to do another test going up 0.2 or 0.3 gr increments to see if that tells me anything about barrel harmonics. 38.5 to 39.5 grains was slow (2550 FPS) but .65 & .54 groups in the bull so that is pretty attractive and I want to look into the alternative.

Yes, it would be great to have a Kestrel but after just buying the NF I am trying my financial advisor's patience (can't afford the divorce). I do put in environmental info and I should get an iPhone App (haven't had a lot of luck with apps; it's a generational thing??)

JimB

 

[Glassaholic]

Your load dev sounds pretty solid and the fact you're using the latest Magnetospeed should indicate you're getting accurate velocity numbers. In lieu of that I'm back to thinking something is wonky with your atmospherics.

I understand having just purchased the NF 7-35 took a dent in your financials and the Kestrel's aren't cheap, at least not the ones with AB in them. Another alternative is what I have, the WeatherFlow WeatherMeter which is an $85 alternative to the pricey Kestrel's, but it is dependent on the BallisticsARC app and smartphones can have issues in the field - be it from losing battery or sitting in the hot sun, etc. I've been wanting the Garmin 701 to support connection to the WeatherMeter for wind but that hasn't happened yet, the Kestrel (to me) has too small of a readout which is why something like the Garmin is more appealing.

Anyway, back to the issue at hand, why is your DOPE so far off from the ballistics engine's predictions? If you download the free version of BallisticsARC it allows you to input one rifle/load and has the ability to link to Online weather stations in your area, this would at least be better than guessing at what your atmospherics might be, I'd be curious if you did this if it made a difference in the ensuing ballistic chart.

Hopefully someone who's an expert at ballistic engines might have more insight (there are a couple Applied Ballistics guys on here like @DocUSMCRetired ) who will hopefully chime in.

 

[spife7980]

Make sure all of your settings are correct again. Weather and rifle settings of course but also the small details like angle of the shot can have huge impacts.

 

[Glassaholic]

One other thought, if you post where you're generally located there may be Hide members nearby who'd be willing to head to the range with you and help you out in person.