Scratching my head.... SET ME STRAIGHT

[Deleted member 115360]

Haha. It happens. Just curious, what speeds are you getting with your PRC?

I've got a bergara wilderness terrain, and so far all I've fired through it is factory Hornady 147eldm, and they shoot lights out, so I probably won't change. I got about 20fps slower than Hornady's published mv when I tested it at about 45°, so I'm probably really close to what they claim at about 80°.

 

[Hugnot]

I don't pay much attention to published BC's.

The stuff in the Berger manual about form factors is an interesting read. The Hornady 4DOF system is a departure from the usual BC stuff. I am a .22-.250 fan, shooting 75 ELDM bullets and the 4DOF system and my Magneto speed chrony comes up with a good accurate firing solutions (most often at rodents).

I think many select bullets using BC's and this makes for inflated BC's.

 

[PRCLITE]

I've got a bergara wilderness terrain, and so far all I've fired through it is factory Hornady 147eldm, and they shoot lights out, so I probably won't change. I got about 20fps slower than Hornady's published mv when I tested it at about 45°, so I'm probably really close to what they claim at about 80°.

Have you ran a chart yet or verified hits at distance? If you ran a chart, how many minutes would you need to adjust for at 500, 750, 1000, 1500?

 

[Deleted member 115360]

This is with a 100y zero.

 

[PRCLITE]

I've got a 100 yard zero as well and at 500 yards I'm at 6.73 minutes.

 

[Deleted member 115360]

If you want to see an interesting comparison, this chart is from my mark V shooting a 300 Weatherby. Compare the retained velocity and energy at 1000y. When I did I felt like I watched someone kill the Easter bunny with a machete..

 

[catamountsierra]

What is your elevation? Higher altitude is thinner air, and thinner air means less drag on the bullet.

 

[Deleted member 115360]

I've got a 100 yard zero as well and at 500 yards I'm at 6.73 minutes.

That 143 is leaving the barrel just a bit faster of course, but it sounds like more than just a little muzzle speed. Now, I haven't verified those numbers yet on my chart to see if they are correct. I set it at 100y, verified impacts at 300y, made a correction in the software, adjusted and called it good for hunting season. I killed several deer with it this year, and it did admirably, but in the next couple of months when it warms up I will be able to really stretch it out and test it at range..

 

[PRCLITE]

What is your elevation? Higher altitude is thinner air, and thinner air means less drag on the bullet.

My elevation when verifying was only 2057' to 2248' ASL

 

[catamountsierra]

My elevation when verifying was only 2057' to 2248' ASL

I'm not sure then, but interested to find out what is going on. Elevation was the only thing readily coming to mind that could explain that big a difference on it's own.

 

[Ranger Rick]

Man, my reading comprehension is terrible this morning. If my second grade English teacher is still alive, I hope she isn't a member of this forum. If she is, I'm sorry Mrs Jankowski, you did teach me better.

Reading comprehension grades vary greatly. Your grammar & punctuation are fine. As a retired BSU professor, I say you pass

 

[Deleted member 115360]

Reading comprehension grades vary greatly. Your grammar & punctuation are fine. As a retired BSU professor, I say you pass

Thank you Sir.

 

[PRCLITE]

That 143 is leaving the barrel just a bit faster of course, but it sounds like more than just a little muzzle speed. Now, I haven't verified those numbers yet on my chart to see if they are correct. I set it at 100y, verified impacts at 300y, made a correction in the software, adjusted and called it good for hunting season. I killed several deer with it this year, and it did admirably, but in the next couple of months when it warms up I will be able to really stretch it out and test it at range..

Just ran it through my gen2 caldwell chronograph which I've only used once with my bow. it seems to be an accurate chronograph thus far. I fired 5 rounds and all were within 8fps with an average of 3086fps. I've plugged those numbers into my ballistics calculator and it still doesn't add up to the field verified 3180. I know the chronograph isn't always exact but it's still 80-90fps slower than I verified in the field. Please note that I am now at sea level and it's a good bit warmer than where I verified in the field so that could make up for the difference but after entering my atmospheric conditions, it still didn't add up. I'm glad I've got the rangefinder I do because it compensates for atmospheric conditions as well as the coriolis acceleration which could have certainly made a difference at longer yardages. All in all I've got my solid field data and I've got a great shooting rifle. My rifle has a 24" barrel so I know that's not the difference since that's what the advertised speed is based off of. Did I just get a great barrel? Not sure.

 

[Deleted member 115360]

Just ran it through my gen2 caldwell chronograph which I've only used once with my bow. it seems to be an accurate chronograph thus far. I fired 5 rounds and all were within 8fps with an average of 3086fps. I've plugged those numbers into my ballistics calculator and it still doesn't add up to the field verified 3180. I know the chronograph isn't always exact but it's still 80-90fps slower than I verified in the field. Please note that I am now at sea level and it's a good bit warmer than where I verified in the field so that could make up for the difference but after entering my atmospheric conditions, it still didn't add up. I'm glad I've got the rangefinder I do because it compensates for atmospheric conditions as well as the coriolis acceleration which could have certainly made a difference at longer yardages. All in all I've got my solid field data and I've got a great shooting rifle. My rifle has a 24" barrel so I know that's not the difference since that's what the advertised speed is based off of. Did I just get a great barrel? Not sure.

Are you using some kind of sweet barrel lube or something? Something that reduces friction? I'm joking obviously.


But hey, can I buy some?