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Interesting study on effect of barrel length:

http://rifleshooter.com/2015/01/308-win ... edal-bthp/

Bitter Clinger wrote:Interesting study on effect of barrel length:

http://rifleshooter.com/2015/01/308-win ... edal-bthp/

Great find. Thanks. The interesting thing is that it averages a 20.4 fps velocity drop per inch of barrel removed..... Which is right in line with the "common wisdom" of a 20 fps loss per inch. I realize that "common wisdom" does not equal what a given round will do in your individual rifle, but it does validate it for guesstimation purposes.

So since I shoot 168s out of my 16" barreled SCAR and 16" barreled Gunsite Scout, this is definitely helpful information. But..... I shoot 175s exclusively out of my (26" barreled) Remington 700. Does the 20 fps loss translate to the slightly slower moving 175 grain bullet? Another question......how does twist affect muzzle velocity? The barrel in the test is a 1:10 twist (more ideal for 175s than 168s). My Remington and Ruger both have 1:10 twists, but my SCAR has a 1:12 twist. Would velocity be significantly different between the 1:12 16" SCAR and 1:10 16" RGS barrels.....assuming the same bullet weights?

I can see that I might have to buy a chronograph.......

One more thing...... When I was training with a former MARSOC Scout Sniper at ETTS 3 weeks ago, and I got out to 800 yards, he asked me if I knew the MV for my ammo (Black Hills 175 grain Match). I told him that I only had a vague idea, based on some chrono work done with a similar hand load, so he taught me how to determine the MV by logging the actual mils of bullet drop at two different known distances on the same range (500 and 800 yards), and then adjusting the MV in my ballistics app (which also accounted for elevation, temperature, humidity, etc.) until the bullet drop in the table matched the actual results on the range. It was a significant difference. My 175 grain handload was being clocked by another forum member on his chronograph, with an average of around 2650 fps from the same rifle, while the app determined the Black Hills load (a fairly "hot" offering which duplicates the M118LR load, which I was also attempting to duplicate with my handload) to be only 2587.......a difference of 63 fps. It causes me to question the actual accuracy of the chronograph, because physics is physics. If you can confirm the amount of drop at multiple known distances with repeatability, then it doesn't matter what the chronograph says the velocity is - because gravity (a known constant) says it is something else......and gravity is representative of the K9 female gender. Three KNOWN values - bullet drop at 500 yards, bullet drop at 800 yards, and the downward acceleration of gravity - outvote whatever the chronograph says. So, for the purposes of measuring the difference in MV while removing inches of barrel, the chronograph might be a valid measuring instrument. But for the purposes of finding out what your bullet is going to do down range at various known distances, those measurements might be mere suggestions.

Hey......maybe I don't need to buy a chronograph!

I have always loved exploring the arcane knowledge of ballistics.

TAM, only one drop at 500 yard is enough. Assuming the rifle is zero at 100 and no significant wind.

Beiruty wrote:TAM, only one drop at 500 yard is enough. Assuming the rifle is zero at 100 and no significant wind.

One drop is enough, but a second value confirms it. You should know.... In ballistics, you should confirm everything.

BTW, the rifle doesn't need to be zeroed at 100. It can be zeroed at any known distance......as long as you know what that distance is. My rifle was zeroed for 200 yards that day, and that is where it will remain zeroed.

The Annoyed Man wrote:

Beiruty wrote:TAM, only one drop at 500 yard is enough. Assuming the rifle is zero at 100 and no significant wind.

One drop is enough, but a second value confirms it. You should know.... In ballistics, you should confirm everything.

BTW, the rifle doesn't need to be zeroed at 100. It can be zeroed at any known distance......as long as you know what that distance is. My rifle was zeroed for 200 yards that day, and that is where it will remain zeroed.

What ballistics apps do you gents use and like on what platform (IOS, Android, etc.)?

Bitter Clinger wrote:

The Annoyed Man wrote:

Beiruty wrote:TAM, only one drop at 500 yard is enough. Assuming the rifle is zero at 100 and no significant wind.

One drop is enough, but a second value confirms it. You should know.... In ballistics, you should confirm everything.

BTW, the rifle doesn't need to be zeroed at 100. It can be zeroed at any known distance......as long as you know what that distance is. My rifle was zeroed for 200 yards that day, and that is where it will remain zeroed.

What ballistics apps do you gents use and like on what platform (IOS, Android, etc.)?

Well, as you know, I'm on iOS. I have been using "Ballistic AE", and it is a really good app, but my trainer advised me to get one called "BallisticsARC" because it was more comprehensive, pairs with my Weatherflow Weather Meter (http://www.weatherflow.com) and imports the data, including wind conditions, AND uses Google Maps to determine a lot of other data like elevation, coriolis effect, etc. In fact, the Google Maps image they use for their app marketing is the 1200 yard range at ETTS: https://geoballistics.com/product/ballisticsarc-app/. The bullet drop/MV data used when I was shooting there was on the Ballistics AE app.

On my android smartphone, I have Strelok+ and External Ballistic Calculator. Both are equally good.

Hands down my most prized posession. Savage Model 112 in 25-06. It was my grandpa's until he passed away and since me and him used it together my grandma gave it to me. This is one of those items I'll go hungry/homeless before I ever thought about getting rid of it. I still have my grandpas handloads that will put bullet on top of bullet at 100 yds. I haven't had the opportunity to shoot much farther than 100 but I am pretty confident I could reach out to at least 300-400 with ease. The scope will be changed out soon for better quality, but for a budget scope the Field and Stream 6-24x50 hasn't been too bad. Oh and my 1911 because why not right?

The Annoyed Man wrote:

Bitter Clinger wrote:

The Annoyed Man wrote:

Beiruty wrote:TAM, only one drop at 500 yard is enough. Assuming the rifle is zero at 100 and no significant wind.

One drop is enough, but a second value confirms it. You should know.... In ballistics, you should confirm everything.

BTW, the rifle doesn't need to be zeroed at 100. It can be zeroed at any known distance......as long as you know what that distance is. My rifle was zeroed for 200 yards that day, and that is where it will remain zeroed.

What ballistics apps do you gents use and like on what platform (IOS, Android, etc.)?

Well, as you know, I'm on iOS. I have been using "Ballistic AE", and it is a really good app, but my trainer advised me to get one called "BallisticsARC" because it was more comprehensive, pairs with my Weatherflow Weather Meter (http://www.weatherflow.com) and imports the data, including wind conditions, AND uses Google Maps to determine a lot of other data like elevation, coriolis effect, etc. In fact, the Google Maps image they use for their app marketing is the 1200 yard range at ETTS: https://geoballistics.com/product/ballisticsarc-app/. The bullet drop/MV data used when I was shooting there was on the Ballistics AE app.

Thanks! Wouldn't that be something if my desire for learning long range shooting and my need for a good ballistics calulator was what finally drove me to an iPhone? I am preparing myself now for the unmitigated abuse that I will deservedly receive...

Bitter Clinger wrote:Thanks! Wouldn't that be something if my desire for learning long range shooting and my need for a good ballistics calulator was what finally drove me to an iPhone? I am preparing myself now for the unmitigated abuse that I will deservedly receive...

You're welcome, but no abuse necessary.....both apps are available for Android products.

jb2012, that is a beautiful rifle. Treasure it. I'll bet that you can get further than 400 with that rifle without much trouble. If anything, your optics might be the limiting factor, but a friend of mine was dinging a 1 MOA steel plate at 800 yards with his AR15 the other day, so a .25-06 ought to be at least that capable. I saw a guy shooting a 6.5 Creedmore at 1200 yards the other day, and a .25 caliber bullet is 6.5mm, so........

If bitterclinger can hit steel at 500yrds with his AR, A bolt rifle in 25-06 should be like a laser

jb2012 wrote:...

What a beautiful stock ... but the throne room could use some work.

and a .25 caliber bullet is 6.5mm, so........

Not exactly. It would be between a 6mm and 6.5mm. 6.5 equals .264 caliber.
Keith

Thank ya for the kind words!