How to correct drop?

[Antares]

Well, I guess I'm learning something here.

I was under the impression that some degree of velocity truing was the norm regardless of whether or not you were using a chrono derived MV.

 

[Lawnboi]

Well, I guess I'm learning something here.

I was under the impression that some degree of velocity truing was the norm regardless of whether or not you were using a chrono derived MV.

To the yardages that most hunters are looking at, I have found the opposite. Transonic can get weird. But to 6 or 700 with most short action stuff if I’m having to true I am more apt to think something is wrong.


It’s been fairly common practice I believe because scopes that didn’t track, hold zero, chronographs that were finicky and seldom used, people zeroing off 3 shots, lack of understanding cone of fire.

I just shot a match that had a good hand full of 1moa targets out to 660. Went in with a balls on zero and a 10 round velocity average and ended the day hitting 80% of my shots with zero truing anything. This is fairly common practice.

 

[Antares]

Maybe part of the disconnect here is how much truing I'm talking about; I'm talking about small corrections, generally less than 0.5 MOA. If I shoot a 10-shot group at 500 and it's 0.5 MOA high, I don't try to figure out why, I just true it down 0.5 MOA (by adjusting MV) and move on. However, I agree if there is a lot more error than expected (e.g., >1 MOA), I would look at my rifle setup and inputs to try to figure out why.

 

[Lawnboi]

Maybe part of the disconnect here is how much truing I'm talking about; I'm talking about small corrections, generally less than 0.5 MOA. If I shoot a 10-shot group at 500 and it's 0.5 MOA high, I don't try to figure out why, I just true it down 0.5 MOA (by adjusting MV) and move on. However, I agree if there is a lot more error than expected (e.g., >1 MOA), I would look at my rifle setup and inputs to try to figure out why.

Not saying you’re right, wrong or otherwise just giving you something to think about. I can understand a time and place for truing and will do it, normally to a certain area or environment. But I’m cautious about it.

If that .5moa is being caused by something environmental that’s a decent amount of error to build in. If it is truly velocity or BC causing 2 clicks of shift I would consider that significant at 5-600 yards.

 

[mtnbound]

The issue with trueing is that environmental are now a factor. Like a longer range zero, your assuming everything is static out there. I understand it sometimes needs to be done and I have done it in the past. Normally I’ll only trust it for the day/ area I’m in. I’m also only speaking to supersonic trueing.

Trueing to certain environmentals has bit me before, partially by just not knowing what I’m looking at(environment), partially because that’s what the internet told me to do.

On top of environmental you could now be truing, any zero error, which a lot of guys have, into your solver. Now down the road when you adjust your zero 2 tenths, everything down range that you trued may not be where it should.

An example would be I can go to a range, on 5 different days throughout the year and need to adjust small amounts. Knowing when and why is the hard part and truing is not a one size fits all the internet plays it to be.

On top of that, almost nobody is trueing with statistically relevant group sizes.

I’ll say it again, using known bullets or known BC, if your truing anything at supersonic ranges, you need to take a hard look at your rifle system and environmental factors.

Since I stopped velocity truing and focusing on the above, I have had zero elevation errors out to supersonic ranges. None. As in I go for a 4 hour ride and am hitting small targets because I trust the BC, know my scope works, have a balls on zero, and have accurate velocity.

Now that Garmin changed the game it’s even easier. If I notice anything strange happening I can slap that thing on my gun for a few shots and eliminate that as a variable. I’ll shoot a few over the chronograph any time I’m confirming zero. It’s simple and makes everything else simple.

Nothing is more frustrating than chasing elevation problems.

If you prefer the guess, check and confirm method that can work too. I do the same thing but instead of burning rounds getting a trued velocity I take 5 shots at small targets on a day where environmental are within my ability to read.

I always look to streamline my work, but I have some follow up questions.

"The issue with trueing is that environmentals are now a factor." Do you mean Temp and Elevation, or?

I'm reading this as if you use a chrono, it eliminates the environmental issues. Can you explain this in more detail?

"Almost nobody is trueing with statistically relevant group sizes." Do you mean the number of rounds fired or actual group size?

"If you're trueing anything at supersonic ranges, you need to take a hard look at your rifle system and environmental factors." For my 6CM, that means I should only be trueing past 1500 yards, and I won't have any elevation errors prior to that using a chrono.

"Now that Garmin changed the game it’s even easier. If I notice anything strange happening I can slap that thing on my gun for a few shots and eliminate that as a variable." You stated earlier that you have had zero elevation errors to SS, so what strange things are you seeing that make you set up the chrono and shoot a few shots to eliminate?

"I’ll shoot a few over the chronograph any time I’m confirming zero." I understand rechecking zero, but why chronograph it unless you have changed something that affects velocity?

Thanks

 

[Castle Rock]

I was under the impression that some degree of velocity truing was the norm regardless of whether or not you were using a chrono derived MV.

I have stopped truing after I found weird things sometimes happening, probably due to atmospheric mirage

It is almost always hot here

 

[Antares]

I have stopped truing after I found weird things sometimes happening, probably due to atmospheric mirage

It is almost always hot here

So what do you do if your impacts aren't lining up exactly with your ballistic calculator?

 

[Castle Rock]

Use what is working on the day, but I always start out with my standardized data

I have seen odd issues arise from truing at certain distances but not others

 

[Antares]

Use what is working on the day, but I always start out with my standardized data

I have seen odd issues arise from truing at certain distances but not others

I'm not following exactly. So you true your data for the day, but then revert back to your standard data on future days? That makes sense to me, but if that's case, I wouldn't say you "have stopped truing."

 

[Lawnboi]

I always look to streamline my work, but I have some follow up questions.

"The issue with trueing is that environmentals are now a factor." Do you mean Temp and Elevation, or?

Temp, elevation, wind both left right up down, mirage off the gun, mirage down the range, lighting effects (into and out of direct sun), parralax changes due to condition changes. Anything environmental.

I'm reading this as if you use a chrono, it eliminates the environmental issues. Can you explain this in more detail?

It dosnt eliminate the environmental issues. But it should be a semi accurate hard number in your solver. “Garbage in, garbage out” as they say, you have a few numbers that are proven, with today’s tech, this is nearly a hard number imo.

"Almost nobody is trueing with statistically relevant group sizes." Do you mean the number of rounds fired or actual group size?

Rounds fired. We are looking at 10 shots minimum for a zero now, guys who are good are shooting multiple 10 round groups for a good zero. Statistically relevant numbers at distance, under exact same conditions are rarely happening. All the above environmentals are a constantly moving number. Look at some of the super precise sports, guys are shooting as fast as possible to try to make the environment stay the same through their string.

"If you're trueing anything at supersonic ranges, you need to take a hard look at your rifle system and environmental factors." For my 6CM, that means I should only be trueing past 1500 yards, and I won't have any elevation errors prior to that using a chrono.

Pretty much. Any real shooting past 7-800 yards on that setup should tell you that environmentals are constantly changing. Getting a shot at those ranges with no environmental impact dosnt exist. This an instance I would true to the day. Hit plenty of 1k targets with the same zero/velocity. I don’t shoot a lot with past supersonic range so I am not going to comment much on what I’d consider elr traps shooting. I’m speaking mainly to ranges we see guys engaging animals.

"Now that Garmin changed the game it’s even easier. If I notice anything strange happening I can slap that thing on my gun for a few shots and eliminate that as a variable." You stated earlier that you have had zero elevation errors to SS, so what strange things are you seeing that make you set up the chrono and shoot a few shots to eliminate?

Elevation issues due to anmmo changes annd environmental changes, specifically mirage. Extreme temp changes, reason I’d throw the chrono on. Barrels are changing through their life, small but they are in speed. Temp makes a difference, environment can make a difference on your velocity. The Garmin makes this stupid easy, I can confirm zero/drop at whatever location I’m traveling to in a few shots without setting anything up.

"I’ll shoot a few over the chronograph any time I’m confirming zero." I understand rechecking zero, but why chronograph it unless you have changed something that affects velocity?

Barrels change through their life. Bullet lots, powder humidity, heat or cold on your ammo. I havnt personally seen a barrel stay the exact same from rounds 200-1000. Just the difference between a cold day and a warm day can be seen on the chronograph. I’m doing this to eliminate as many variables possible. Hunting maybe not the biggest deal but in a match setting shooting at 1-2moa targets a tenth or 2 can make a hit or a miss.

Thanks

 

[Castle Rock]

No, I don’t true at all. If I notice on the day I need a couple of extra clicks set a certain range. I’ll extrapolate that but I never touch my solid data.

 

[ATL]

I did not read all the posts, so I apologized if this info was provided already.

At 580 yards, 1 MIL is equal to 20.88” (3.6” x 5.8). To adjust for the 3.6” of additional drop you experienced than what estimated, add another .17 MIL (round up to 2 MIL), or a solution of 3.3 MIL at 580 yards.

 

[mxgsfmdpx]

No, I don’t true at all. If I notice on the day I need a couple of extra clicks set a certain range. I’ll extrapolate that but I never touch my solid data.

So you don’t kill anything at long range then?

 

[mxgsfmdpx]

Lots of advice here that can be helpful “on the range” but if you actually want to kill animals at long range, ignore those posts please.

“Good data” from a “chrono” and “good BC” and “good calculator” is great and helpful, but it never 100% tells you the full story for making consistent impacts at long ranges. Shooting at long ranges and verifying hits does that. It’s all mathematical theory and physics that requires proof down range.

If you aren’t making adjustments to real world impacts with that gun and scope and ammo down range, and not adjusting your charts to current environmentals after trueing dope to real world impacts, you simply aren’t consistently shooting and killing at long ranges. Go out and shoot and observe/learn.

 

[northernalpine]

@mxgsfmdpx pretty much nailed it.

Get an app that has profile truing built in, shoot at 650-800yds to true your setup, go kill things when the conditions are within your ability.

Not affiliated with Revic/GW but their app is solid

 

[bojangles808]

Lots of advice here that can be helpful “on the range” but if you actually want to kill animals at long range, ignore those posts please.

“Good data” from a “chrono” and “good BC” and “good calculator” is great and helpful, but it never 100% tells you the full story for making consistent impacts at long ranges. Shooting at long ranges and verifying hits does that. It’s all mathematical theory and physics that requires proof down range.

If you aren’t making adjustments to real world impacts with that gun and scope and ammo down range, and not adjusting your charts to current environmentals after trueing dope to real world impacts, you simply aren’t consistently shooting and killing at long ranges. Go out and shoot and observe/learn.

If you have a 10 shot zero dead nuts and 10 shot string avg in your Chrono. Plug that all in and Go out to 700 and youre low. what are you tweaking? BC? Not your MV right. Or maybe that's where the trying profiles come in and ined to dig into that. What SDs in factory ammo start to worry you . In the 20s 30s?

 

[Antares]

@mxgsfmdpx pretty much nailed it.

Get an app that has profile truing built in, shoot at 650-800yds to true your setup, go kill things when the conditions are within your ability.

Not affiliated with Revic/GW but their app is solid
View attachment 766222

Shooter has it built in too. I love that feature, especially coming from 4DOF, which doesn’t have it (I don’t think).

 

[wind gypsy]

Lots of advice here that can be helpful “on the range” but if you actually want to kill animals at long range, ignore those posts please.

“Good data” from a “chrono” and “good BC” and “good calculator” is great and helpful, but it never 100% tells you the full story for making consistent impacts at long ranges. Shooting at long ranges and verifying hits does that. It’s all mathematical theory and physics that requires proof down range.

If you aren’t making adjustments to real world impacts with that gun and scope and ammo down range, and not adjusting your charts to current environmentals after trueing dope to real world impacts, you simply aren’t consistently shooting and killing at long ranges. Go out and shoot and observe/learn.

I think you’re misinterpreting what lawnboi and castle are saying or I just disagree.

If the dudes asking these questions “true” a ballistic calc based on an AB custom curve and measured velocity at ranges like 600 yards, they are more likely to worsen their data by “truing” in the impacts from current conditions they are unaware of than actually improve that baseline ballistic profile for future use with different conditions.

 

[BBob]

If that .5moa is being caused by something environmental that’s a decent amount of error to build in. If it is truly velocity or BC causing 2 clicks of shift I would consider that significant at 5-600 yards.

But if the guy shoots/practices much at all he'll figure that all out pretty quick. As I said somewhere before good zero's aren't usually a one and done proposition and neither are offsets or most anything else we do. It takes a little time and effort to repeat and test to come to a good reliable setup with full knowledge that day to day environmental's are going to mess with you.

 

[Castle Rock]

So you don’t kill anything at long range then?

I certainly do with proven data, do you true in the field before taking a shot?