Let’s build a youth forever rifle!

[mxgsfmdpx]

I take back all the good things I said about my gun smith. He keeps making me make decision I don’t like making.

16.5” or 18” barrel. Both are on the shelf!

Help me!

Depends on MER

 

[Ucsdryder]

Depends on MER

Haha i knew that was coming. Its so hard to get away from the more velocity the better mindset!

 

[sierracharlie338]

I take back all the good things I said about my gun smith. He keeps making me make decision I don’t like making.

16.5” or 18” barrel. Both are on the shelf!

Help me!

I’m in the lowlands of Texas so I’d opt for the 18 but if you’re higher up 16.5 would prob be fine for her hunting rig.

 

[wind gypsy]

I take back all the good things I said about my gun smith. He keeps making me make decision I don’t like making.

16.5” or 18” barrel. Both are on the shelf!

Help me!

Sounds like a carbon barrel problem. Neither

 

[Ucsdryder]

Sounds like a carbon barrel problem. Neither

Haha I was going to keep that part to myself! Yeah I went CF. Gemma’s request..she thinks the gray swirls are pretty. It’s hard to argue with her. 18” was her request over 16.5” so we’re moving forward.

Defiance classic
18” proof sendero CF
trigger tech special

I might have gotten a little ahead of myself with this build, when I was her age I was shooting a 5 times hand me down rifle.

 

[Marbles]

I don't have time to google immediately, DA...

So, you are at sea level? I think 7-10k feet in Colorado would be an easy 500yds.

Density altitude (DA) is a single number composite of altitude, barometric pressure, and temperature.*** Basically, if barometric pressure and temp are held constant, it is the altitude you would be at.

I live at see level, in the 8 months I have been paying attention to it my DA has ranged from -7000 to 3500 feet. The actual altitude is unchanged, but bullet behavior is effected quite a bit.

The -60 example above would be a DA of -13,000 feet.

***For the pedantic nerds like myself, DA is derived from temp, station pressure, and dew point temperature. The actual calculation is complex enough I would not mess with it.

 

[mxgsfmdpx]

Density altitude (DA) is a single number composite of altitude, barometric pressure, and temperature.*** Basically, if barometric pressure and temp are held constant, it is the altitude you would be at.

I live at see level, in the 8 months I have been paying attention to it my DA has ranged from -7000 to 3500 feet. The actual altitude is unchanged, but bullet behavior is effected quite a bit.

The -60 example above would be a DA of -13,000 feet.

***For the pedantic nerds like myself, DA is derived from temp, station pressure, and dew point temperature. The actual calculation is complex enough I would not mess with it.

Yes sir an actual full DA calculation is always ideal and the most accurate but it’s almost never really feasible when hunting. By the time someone gets all of their current weather and full data into an app and get a calculation, lots of times the opportunity has gone by. Or the yardage has changed, etc.

If you factor in just elevation and temp, and have some pre made cards based on the forecast and known elevations, it’s much faster. I have little laminated cards on a key ring in an outside pouch of my pack. The elevations are different colors and then they are sorted by temp low to high.

I can confidently say in my experience with just about all hunting shots out to 1,000 yards that just using temp and elevation into the calculation is near identical to doing a full DA calculation.

You’re going to miss because of a poor shot or a poor wind call way before you’ll miss because you didn’t do a full DA calc and just used elevation and temp instead. At least, that’s what I’ve seen in the field.

 

[Marbles]

Yes sir an actual full DA calculation is always ideal and the most accurate but it’s almost never really feasible when hunting. By the time someone gets all of their current weather and full data into an app and get a calculation, lots of times the opportunity has gone by. Or the yardage has changed, etc.

If you factor in just elevation and temp, and have some pre made cards based on the forecast and known elevations, it’s much faster. I have little laminated cards on a key ring in an outside pouch of my pack. The elevations are different colors and then they are sorted by temp low to high.

I can confidently say in my experience with just about all hunting shots out to 1,000 yards that just using temp and elevation into the calculation is near identical to doing a full DA calculation.

You’re going to miss because of a poor shot or a poor wind call way before you’ll miss because you didn’t do a full DA calc and just used elevation and temp instead. At least, that’s what I’ve seen in the field.

The cards are a good back-up. Within the ranges I well shoot at an animal +/- 2500 feet DA is just fine (5000 ft DA change at 500 yards is a 2.3 inch POI change (0.1 mil) and 100 fps difference in impact velocity) for my gun/bullet. So looking at the Kestrel when there are large changes in temp/barometer/elevation and just remembering that for the next few hours works fine. For most shots, were I hunt, knowing quick drop calculations for 3000 ft DA gets me within margin of error.

At the moment my hard limit on an animal is 400 yards, if I get enough mountain shooting and reliable get 90% first round hits, I will push it out as far as 600 yards and DA accuracy will be a little more important. I'll shoot for fun at longer ranges though.

I suspect I just found another articulation of the argument for high BC bullets even when something else will work.

 

[mxgsfmdpx]

The cards are a good back-up. Within the ranges I well shoot at an animal +/- 2500 feet DA is just fine (5000 ft DA change at 500 yards is a 2.3 inch POI change (0.1 mil) and 100 fps difference in impact velocity) for my gun/bullet. So looking at the Kestrel when there are large changes in temp/barometer/elevation and just remembering that for the next few hours works fine. For most shots, were I hunt, knowing quick drop calculations for 3000 ft DA gets me within margin of error.

At the moment my hard limit on an animal is 400 yards, if I get enough mountain shooting and reliable get 90% first round hits, I will push it out as far as 600 yards and DA accuracy will be a little more important. I'll shoot for fun at longer ranges though.

I suspect I just found another articulation of the argument for high BC bullets even when something else will work.

I like where you’re at on this topic. I wouldn’t think a difference in full DA calc and a temp/elevation calc only would have a 2.3” discrepancy at 400 yards. I need to search for a thread on this topic as I probably have some things to learn and then go try. Won’t clutter up this one.

Edit: Just did a quick calculation as if I was to take an 800 yard shot at a 12” target with the current weather data.

Actual elevation 2,200. Density altitude based on current data is 110 degrees, 29.7 station pressure, and 56 degree dew point makes for 3,625 DA.

With my .260 shooting 129 SST…

Using just elevation and temp:
MIL UP: 5.7
Impact velocity: 1,708

Using DA calc:
MIL UP: 5.6
Impact velocity: 1,762

 

[Formidilosus]

I like where you’re at on this topic. I wouldn’t think a difference in full DA calc and a temp/elevation calc only would have a 2.3” discrepancy at 400 yards. I need to search for a thread on this topic as I probably have some things to learn and then go try. Won’t clutter up this one.

Edit: Just did a quick calculation as if I was to take an 800 yard shot at a 12” target with the current weather data.

Actual elevation 2,200. Density altitude based on current data is 110 degrees, 29.7 station pressure, and 56 degree dew point makes for 3,625 DA.

With my .260 shooting 129 SST…

Using just elevation and temp:
MIL UP: 5.7
Impact velocity: 1,708

Using DA calc:
MIL UP: 5.6
Impact velocity: 1,762

Check your numbers again. You are over 6,000fy DA with those numbers.

 

[Marbles]

I like where you’re at on this topic. I wouldn’t think a difference in full DA calc and a temp/elevation calc only would have a 2.3” discrepancy at 400 yards. I need to search for a thread on this topic as I probably have some things to learn and then go try. Won’t clutter up this one.

I don't think it would, that number was to show that a 5000 ft DA error is only off by 2.3" at 400 yards. The temp/elevation method would by much closer than that, even if guessing temp based on feel and allowing for error in elevation I doubt you would be off by over 1000 ft DA from measured (based on what Form has said, it will probably be closer than that)

 

[mxgsfmdpx]

Check your numbers again. You are over 6,000fy DA with those numbers.

I used a quick free online calculator entering the values. I wonder what this one isn’t taking into account to come up with value?


I moved away from DA calculators when I quit shooting comps and long range varmint comps 10 years ago. It’s been a while.

I’ve honestly just used current temp and current elevation with cheat cards and have had great success on big game out to 1,000 yards. I guess it’s a good thing they are big targets haha.

I’ll start a new thread and tag a few folks in there to discuss further, unless there is some data somewhere already?

Thanks.

 

[Formidilosus]

I used a quick free online calculator entering the values. I wonder what this one isn’t taking into account to come up with value?
View attachment 745613

I moved away from DA calculators when I quit shooting comps and long range varmint comps 10 years ago. It’s been a while.

I’ve honestly just used current temp and current elevation with cheat cards and have had great success on big game out to 1,000 yards. I guess it’s a good thing they are big targets haha.

I’ll start a new thread and tag a few folks in there to discuss further, unless there is some data somewhere already?

Thanks.

There is something not correct about that.

This is what you should be getting, or something close-




Using a DA chart with just temp and elevation puts it between 6,100 and 6,200 ft DA. Using just real temp and real elevation results in not more than a 100 foot or so difference in DA than absolute correct DA.

 

[mxgsfmdpx]

There is something not correct about that.

This is what you should be getting, or something close-

View attachment 745617


Using a DA chart with just temp and elevation puts it between 6,100 and 6,200 ft DA. Using just real temp and real elevation results in not more than a 100 foot or so difference in DA than absolute correct DA.

Makes sense.

I just threw it all in Strelok pro for fun, using my phones weather app to give me a calc with my .260 at 800 yards. The result was up 5.6 MIL which is within .1 MIL of what I would have used for elevation dial for that shot if I went out and did that shot right now.

Sorry @Ucsdryder Ill make a new thread to discuss this in a bit.

 

[Ucsdryder]

Makes sense.

I just threw it all in Strelok pro for fun, using my phones weather app to give me a calc with my .260 at 800 yards. The result was up 5.6 MIL which is within .1 MIL of what I would have used for elevation dial for that shot if I went out and did that shot right now.

Sorry @Ucsdryder Ill make a new thread to discuss this in a bit.

nope, I’m following along too. I’ve been using zeiss RFs for the last 4 years so took a lot of this for granted. I just googled it, the pilots take this shit seriously!

 

[mxgsfmdpx]

nope, I’m following along too. I’ve been using zeiss RFs for the last 4 years so took a lot of this for granted. I just googled it, the pilots take this shit seriously!

Right on. We used to go crazy with it at the VHA competitions and qualifiers. Trying to get confirmed kills on varmints at over 2,000 yards take a special kind of idiot (me).