View Full Version : 175gr SMK's @ 2570 MOA data to 1000
Mark bumped up our loads last week and we were able to get the 175's flying at 2,570 which is as little better. He loaded with 43.8 Varget and accuracy was very good.
I am getting a new scope and curious how I build a chart the shows based on bullet weight, speed, BC...you need "1? clicks to hit 600 yards or whatever it may be.
I have heard there are online charts for this, but I never played with them. Any help =gracias!
ICANHITHIMMAN
10-09-11, 19:11
I have NF software on my PDA it works very well! Here is a link you have to sign up but this progam will save your loads and you can print the drop data. THere are programs for your android phone or your ipod
http://www.longrangehunting.com/ballistics.html
Cheapest way to get what you are after, is the way I do it. (for something you can take in the field anyway)
Buy a Kestrel 4000 or better.
Buy an iTouch.
Buy an otterbox to kee the itouch dry and protected.
Download "Ballistic FTE" from the app store.
I keep my itouch in my databook. Ballistic will give you a firing solution based on your load and current conditions. It's been accurate to within a tenth of a mil for me on everything I've tested it with, including 308 out to 1540yds.
Another app to try is "bulletflight" by knights armament. It is not as powerful as Ballistic, but is easier to use for beginners and still very accurate to 1000yds. Can't say I've really used it past that, as I kind of "out grew" it before I started pushing past 1k yds.
bnanaphone
10-10-11, 10:10
Some good info here. I have been using "Bulletflight" on my iphone and it works pretty well for my, limited knowledge, needs. My only issue is that I don't have a chronograph to get accurate MV numbers from my rifles. I only shoot commercial ammo (BH, Hornady & FGMM) so I try my best to find relatively accurate numbers for my barrels via the internets. I do like Orkan's idea of the Kestrel and ipad, hello Christmas!
I only use the software for my LMT .308 with 16" CL barrel and my 16" BCM SS RECCE, for now. Will be getting a bolt gun in the coming months.
You can also do this on the internet and print it out.
As some have mentioned you'll also need weather info. The most accurate way is with a Kestrel NOT the cheapest way though.
If you have an Iphone I use a program called Ballistic FTE. It works great. It even uses the same algorithm as JMB online.
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
Taking charts with you does not account for environmental variables at your shooting location. It's nice to have them around for a fallback, but in that case I have my actual dope cards to wing it off of.
To get really accurate, a kestrel with an interlink to a trimble nomad is about the best you can get. Very expensive though. Around $3500 by the time its all setup with what you need. It's bigger and heavier too.
My iTouch is small, and cheap. Kestrel, iTouch, and the databook all have their place in my pack.
Some good info here. I have been using "Bulletflight" on my iphone and it works pretty well for my, limited knowledge, needs. My only issue is that I don't have a chronograph to get accurate MV numbers from my rifles. I only shoot commercial ammo (BH, Hornady & FGMM) so I try my best to find relatively accurate numbers for my barrels via the internets.
Im having the same issues as these.. Has anyone here chrono'd 175 gr FGMM out of a 20" barrel (preferably factory remington)?
Federal's site lists it at ~2600 fps, but i think that is from a 26" barrel.
From Sierra's site
http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=2275&bullettype=0
mil----after clicking link, back space, change to moa if that's what you have. you can also change the data, I put in certain temps and likely DA based on your AO
http://www.jbmballistics.com/cgi-bin/jbmcard-5.1.cgi
Im having the same issues as these.. Has anyone here chrono'd 175 gr FGMM out of a 20" barrel (preferably factory remington)?
Federal's site lists it at ~2600 fps, but i think that is from a 26" barrel.
Doubt it's going 2600, I know Blackhills advertised at 2600 with their 175's and with an sps, lucky to break 2500, I was getting 2475-2500, another shooter got 2525 from a 22" sneider barrel.
I agree with Mark, dont go by what the manufacturer says. I ran into the same issue with BH and Corbon.
Out of my 25" AI with can I got about 2585 for both BH and corbon.
You really need to chrono it out of your gun to get accurate MV.
You really need to chrono it out of your gun to get accurate MV.
With an accurate chrono. It's a very common thing for cheap chrono's to be +/- 100fps or more.
Well not an expensive chrono but my Prochrono reads within 10fps of my buddy's Ohler.
59 degrees, moly'd 175 smk's averaged 2641fps with RL15 in my XCR Tactical, a stainless version of the LTR, 20" barrel.
stinkyDrunk
10-10-11, 18:34
Mark bumped up our loads last week and we were able to get the 175's flying at 2,570 which is as little better. He loaded with 43.8 Varget and accuracy was very good.
I am getting a new scope and curious how I build a chart the shows based on bullet weight, speed, BC...you need "1? clicks to hit 600 yards or whatever it may be.
I have heard there are online charts for this, but I never played with them. Any help =gracias!
If you have an Android device: Shooter (http://shooter.kndy.net/)
Screenshots at link.
59 degrees, moly'd 175 smk's averaged 2641fps with RL15 in my XCR Tactical, a stainless version of the LTR, 20" barrel.
That is very fast out of a 20" barrel.
With an accurate chrono. It's a very common thing for cheap chrono's to be +/- 100fps or more.
True, but you can confirm MV by going out shooting and comparing the data to your actual dope. It's truing the gun.
True, but you can confirm MV by going out shooting and comparing the data to your actual dope. It's truing the gun.
Actually, that is tuning the ballistic calculator. Knowing true muzzle velocity and inputting the correct variables into ballistic, and having it output the correct dope... that is the goal. Then if it is accurate at one condition, it will likely be accurate across the range of conditions.
Shooting the rifle at various ranges, and fudging the numbers in the ballistic calc to match what you see, only ensures that the trajectory matches at THAT specific condition. Now, it will be close, sure... but it isn't unrealistic to see a 0.3-0.5mil variance the farther you get away from your "tuned condition." This practice reinforces bad data, and shouldn't be encouraged.
Obviously I agree that real world shooting needs to be compared to what your calc is showing you. Otherwise you won't be able to trust its numbers. However, there is much more to it than just changing the numbers in the ballistic calc to suite a trajectory from a single range trip. (not that I was inferring you said that) For instance, bad numbers in your ballistic calc can also be an indication of a scope turret that does not track correctly or a reticle that does not subtend correctly. Those are just two of the external variables that can affect your perceived dope inaccuracies.
mcmillanman5
10-11-11, 17:54
If you shoot the 175 SMK you should check out the FDAC:
http://www.actsvirginia.com/sliderule.php
While I agree that a kestrel and ballistic computer are best this is great solution that costs way less. I have one and have been quite impressed with it. Its easy to use and has given me fairly accurate drops.
A friend of mine just has his new 270 WSM out in preparation for his upcoming deer hunt. He used his chronograph and obtained his velocity. He then shot at 500 yards, and when the corrected drop was entered into the G7 program, the corrected velocity ended up being 218 fps. lower. I'm assuming the corrected drop chart, at all the different yardages, will be spot on, but that seems like quite a bit of a drop. I don't get how the velocity could be that far off. I haven't heard of anyone speaking about the accuracy of chronographs. Anyone have any info. on this?
Oehler 35p
PVM-21
Those two chrono's pretty much rule the roost, with the 35p being the elder of the two.
Actually, that is tuning the ballistic calculator. Knowing true muzzle velocity and inputting the correct variables into ballistic, and having it output the correct dope... that is the goal. Then if it is accurate at one condition, it will likely be accurate across the range of conditions.
Shooting the rifle at various ranges, and fudging the numbers in the ballistic calc to match what you see, only ensures that the trajectory matches at THAT specific condition. Now, it will be close, sure... but it isn't unrealistic to see a 0.3-0.5mil variance the farther you get away from your "tuned condition." This practice reinforces bad data, and shouldn't be encouraged.
Obviously I agree that real world shooting needs to be compared to what your calc is showing you. Otherwise you won't be able to trust its numbers. However, there is much more to it than just changing the numbers in the ballistic calc to suite a trajectory from a single range trip. (not that I was inferring you said that) For instance, bad numbers in your ballistic calc can also be an indication of a scope turret that does not track correctly or a reticle that does not subtend correctly. Those are just two of the external variables that can affect your perceived dope inaccuracies.
I'm not sure I'm following you.
What I'm talking about is truing the gun. I'm using Accuracy 1st Whiz Wheel. It gives me the adjustments for all ranges being shot. That;s great, but you you'r gun might be just a bit different, so we have to go out and shoot the data and true it to OUR gun.
The same thing can happen with MV, Shoot at a target right at the transonic barrier, say 800m for a 175gr SMK.
So for .308 lets say its about 800m, pick a point of aim shoot at that point, then take the difference from the POA and the POI do the math and you'll get a true MV. I'm a bit tired so I this could be a bit more clear with my explanation.
There's an articel about this on their site that explainshow to do it.
dieselgeek
10-11-11, 20:13
175g SMKs 43g RL 15 got me close to 2700 FPS out of my 24 inch .308 I think I had 34.75 MOA at 1010 yards.
I use known dope, an Kestrel device, and shooter to help me get my numbers. It's worked very well for me.
I'm not sure I'm following you.
What I'm talking about is truing the gun. I'm using Accuracy 1st Whiz Wheel. It gives me the adjustments for all ranges being shot. That;s great, but you you'r gun might be just a bit different, so we have to go out and shoot the data and true it to OWR gun.
For the record, the transonic barrier of a 175SMK out of most 308's is closer to 1100yds. As you approach sea level, it will drop to just below a thousand on a 70f day.
I'm not very familiar with that whiz wheel product, as I don't use it. So you'll have to forgive my ignorance of it. However, when properly using a ballistic calc, you want the ballistic calc to produce correct numbers. The only way it will produce accurate info across all conditions, and all distances, with all loads is to feed it accurate variables.
Yes, I'm aware that you can reverse engineer your velocity without the aid of a chrono, and be pretty close in that reading, but that is not what I'm talking about. I'm talking about computing a firing solution that is within 0.1 mil accurate no matter if its -25 degrees, or 125 degrees. The only way a ballistic calculator will do that, is if you input the correct variables accurately. This means you must tell it the exact velocity, and the exact BC of the bullet, along with the environmental data of course. The point being, you cannot fudge the velocity so that the drop chart generated by the calc, matches what you see at X range on X day. When the conditions change, they will not match anymore. The more they change from that condition, the more error will exist in the new trajectory table.
Say you compute a solution for 1000yds with a 308, and its calling for 10.0 mils of elevation. You fire, and your shot hits 0.5 mils low. You then come up 0.5 mils and hit dead center. Some people will then go into their ballistic calculator and modify their velocity to a slower number to make up for the difference. Then the modified trajectory chart shows 10.5 mils instead of the original 10.0 mils. Then the shooter saves the profile, and considers it good.
Next time out, they are shooting at 1000yds again, but instead of being say 100f out, this time its 30f out. The ballistic calc is running off an impression of a slower bullet, and computes accordingly. Except this time the shooter shoots 0.5 mils OVER the target. The likely cause is because the shooter did not input the correct variables in the first place, and fudged the velocity to match the condition... instead of troubleshooting what was actually going on.
I guess my point is that I never reinforce bad data, at any cost. If you enter the best data you can into the ballistic comp, and your given trajectory is obviously off, then you need to take the proper steps to find out what variable is not entered correctly. This will lead to a much greater level of trust with your chosen ballistic calculator and much greater success in the field.
This is why it is important to get the correct velocity of your particular round out of a given rifle. That number, along with the BC, are the two most important variables aside from environmental data. If either are not correct, your calc will spit out bad trajectory charts. Changing the velocity to suite your condition for a matched trajectory... is not an acceptable policy in my opinion.
Actually, that is tuning the ballistic calculator. Knowing true muzzle velocity and inputting the correct variables into ballistic, and having it output the correct dope... that is the goal. Then if it is accurate at one condition, it will likely be accurate across the range of conditions.
Shooting the rifle at various ranges, and fudging the numbers in the ballistic calc to match what you see, only ensures that the trajectory matches at THAT specific condition. Now, it will be close, sure... but it isn't unrealistic to see a 0.3-0.5mil variance the farther you get away from your "tuned condition." This practice reinforces bad data, and shouldn't be encouraged.
Obviously I agree that real world shooting needs to be compared to what your calc is showing you. Otherwise you won't be able to trust its numbers. However, there is much more to it than just changing the numbers in the ballistic calc to suite a trajectory from a single range trip. (not that I was inferring you said that) For instance, bad numbers in your ballistic calc can also be an indication of a scope turret that does not track correctly or a reticle that does not subtend correctly. Those are just two of the external variables that can affect your perceived dope inaccuracies.
That all makes great sense and I'm guilty of fudging the numbers to come up with a chart that works at a specific condition.
I run Ballistic FTE on my iPhone and the biggest issues I have are understanding the ballistic coefficient and which drag model to use. A little research goes a long way and could really help me out I guess.
The method I've chosen works pretty well. For the area I shoot I've gone out in different temperature conditions, from HOT (100+) to TX cold (mid 20's), shot at different ranges and put together a dope chart. I shoot at altitude from MSL to 2,000 ft and understand what my differences are.
I understand that if I ever go to CO in the winter I'll need a better plan, but for my AO it works.
For the record, the transonic barrier of a 175SMK out of most 308's is closer to 1100yds. As you approach sea level, it will drop to just below a thousand on a 70f day.
I'm not very familiar with that whiz wheel product, as I don't use it. So you'll have to forgive my ignorance of it. However, when properly using a ballistic calc, you want the ballistic calc to produce correct numbers. The only way it will produce accurate info across all conditions, and all distances, with all loads is to feed it accurate variables.
Yes, I'm aware that you can reverse engineer your velocity without the aid of a chrono, and be pretty close in that reading, but that is not what I'm talking about. I'm talking about computing a firing solution that is within 0.1 mil accurate no matter if its -25 degrees, or 125 degrees. The only way a ballistic calculator will do that, is if you input the correct variables accurately. This means you must tell it the exact velocity, and the exact BC of the bullet, along with the environmental data of course. The point being, you cannot fudge the velocity so that the drop chart generated by the calc, matches what you see at X range on X day. When the conditions change, they will not match anymore. The more they change from that condition, the more error will exist in the new trajectory table.
Say you compute a solution for 1000yds with a 308, and its calling for 10.0 mils of elevation. You fire, and your shot hits 0.5 mils low. You then come up 0.5 mils and hit dead center. Some people will then go into their ballistic calculator and modify their velocity to a slower number to make up for the difference. Then the modified trajectory chart shows 10.5 mils instead of the original 10.0 mils. Then the shooter saves the profile, and considers it good.
Next time out, they are shooting at 1000yds again, but instead of being say 100f out, this time its 30f out. The ballistic calc is running off an impression of a slower bullet, and computes accordingly. Except this time the shooter shoots 0.5 mils OVER the target. The likely cause is because the shooter did not input the correct variables in the first place, and fudged the velocity to match the condition... instead of troubleshooting what was actually going on.
I guess my point is that I never reinforce bad data, at any cost. If you enter the best data you can into the ballistic comp, and your given trajectory is obviously off, then you need to take the proper steps to find out what variable is not entered correctly. This will lead to a much greater level of trust with your chosen ballistic calculator and much greater success in the field.
This is why it is important to get the correct velocity of your particular round out of a given rifle. That number, along with the BC, are the two most important variables aside from environmental data. If either are not correct, your calc will spit out bad trajectory charts. Changing the velocity to suite your condition for a matched trajectory... is not an acceptable policy in my opinion.
I agree with everything you said. What I was saying, and this is just part of my anal retentiveness, is that even with the right numbers, I personally like to shoot the numbers and confirm what the device is telling me. This builds confidence in the device and lets you know the all your numbers are accurate.
But again you're absolutely right, MV and BC are the most important factors to get right.
Too many people just use the MV numbers on the box and 99% of the time they are incorrect for one's gun.
The same goes for BC. One needs to use the right BC value for the MV being shot as it changes with the MV.
At the end of the day it's all about making that first cold bore shot land on it's target and that's only happening if one is using good data and fundamentals.
At the end of the day it's all about making that first cold bore shot land on it's target and that's only happening if one is using good data and fundamentals.
I couldn't agree more!
That's the way it works, keeping it civil to share info and learn. :cool:
That's the way it works, keeping it civil to share info and learn. :cool:
Not that hard when you have someone like rickp in the conversation, who's clearly intelligent and level headed. We were misunderstanding what each other was saying, as he was talking about one thing, and I was talking about a different thing. Yet I think this thread will serve up some good points to those looking for info.
I expected this thread to go an entirely different route, but rickp more than surprised me with his willingness to argue the topic, and not start taking ridiculous personal shots as is so common with members that come from that "other" site. ;)
Rickp, for that you have my thanks and I am glad to have you here to contribute to the more technical discussions. :thank_you2:
Indeed, staying calm and not name calling, etc is key. In the end, even if you don't agree or do something different, it's not necessarily wrong or the end of the world.
Now let's FIGHT over the necessity of an extended Bolt Handle! :cool:
[QUOTE=
Now let's FIGHT over the necessity of an extended Bolt Handle! :cool:[/QUOTE]
The rifle that came back from Bartlien still has the standard bolt handle. I do like the AI handle, but that came that way.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.