Do I have this figured out, or am I out to lunch?

[JGorski]

I zeroed my 6 Creed at 300, then went to 200 and it shot +3.3", 100yd shot went +2.6". Looking at my Hornady Ballistic calculator it tells me that the velocity is 3355fps, the load is 42grs RE17, 105 Hybrid/Hornady HPBT.
Have another load which is 42.2grs H4350 and should be right around 3158fps figuring from what Frank Green is getting from his 23' tube and 42grs H4350 from his 6 Creed. I know i should invest in a chronograph but it is what it is, so I use trajectory figures, that being said it looks good to me, your thoughts? Sound good to you guys?

 

[KYS]

I'd say your numbers are close. I might even back them down a touch. I find the 6 Creedmoor to run best in the 3150-3180 range. I would be under the assumption you are going to wear the throat out pretty quick running it at that speed/pressure. How many rounds are you getting off before the bolt gets sticky when ejecting?
One question I would ask is why are you zeroing at 300 yards?

 

[turbo54]

Trying to back-figure velocity of a high speed, high BC round based on observed trajectory between 100 and 300 yards is like trying to pick fly shit out of the pepper.

Even 600 yards isn't really enough.

Try 1000.

 

[clayne_b]

I agree with turbo54

I do this with my .308 between 500 and 1000 off of a 100 yard zero, Tweak the app or program to match actual shot data. Has always worked very well for me.

 

[clayne_b]

I agree with turbo54

I do this with my .308 between 500 and 1000 off of a 100 yard zero, Tweak the app or program to match actual shot data. Has always worked very well for me.

 

[JGorski]

I'd say your numbers are close. I might even back them down a touch. I find the 6 Creedmoor to run best in the 3150-3180 range. I would be under the assumption you are going to wear the throat out pretty quick running it at that speed/pressure. How many rounds are you getting off before the bolt gets sticky when ejecting?
One question I would ask is why are you zeroing at 300 yards?

The amount of RE17 Im loading doesnt seem to be of high pressure, 42.1grs does on occasion give me a sticky bolt, loaded 41.9grs tonight for tomorrows' match, that load produced my best 300yd group to date.
I had the rifle zeroed at 300 already so all I had to do was go back(to 200 & 100) and go home to see what the Hornady ballistic calculator said. In my heart I do trust Im pretty close to this 3355fps since German Salazar and Bob Jensen got 3311 from the 6XC, which from their data was 200fps over their H4350, though they were shooting a 31" tube, nonetheless it was 200fps more.

The match is a 600yd BR contest.

 

[JGorski]

Well I moved my scope up 26 clicks, Ill let you guys know how close I can get to the sighter plate.

 

[bward]

Trying to back-figure velocity of a high speed, high BC round based on observed trajectory between 100 and 300 yards is like trying to pick fly shit out of the pepper.

Even 600 yards isn't really enough.

Try 1000.

This was my exact thought when reading the post. I like to go to 1200 to confirm my drop tables.

 

[KYS]

Or.... go borrow a chronograph!!!

 

[JGorski]

Or.... go borrow a chronograph!!!

Well, turns out I dont need one, on my first sighter I was .5min low at 600yds. 2 clicks and I was in business. With the 200fps less H4350 3 clicks put me thru the sighter plate first shot.

 

[bward]

Well, turns out I dont need one, on my first sighter I was .5min low at 600yds. 2 clicks and I was in business. With the 200fps less H4350 3 clicks put me thru the sighter plate first shot.

If you are going to be serious about this game you need one. Determining my velocity is one of the last things I rely on my chronograph for. Determining ES's to eliminate vertical at 1000+ is where they really shine.

 

[JGorski]

If you are going to be serious about this game you need one. Determining my velocity is one of the last things I rely on my chronograph for. Determining ES's to eliminate vertical at 1000+ is where they really shine.

I will eventually get one, thanks bward.

 

[bward]

I will eventually get one, thanks bward.

I think you will see how helpful they are for working up a load after you use it a few times. If you are wanting to get into one on the cheap, here is one I have heard several good things about. I've never used one personally, but you wouldn't be out much if it sucked.

Competition Electronics ProChrono Digital Chronograph

 

[JGorski]

I think you will see how helpful they are for working up a load after you use it a few times. If you are wanting to get into one on the cheap, here is one I have heard several good things about. I've never used one personally, but you wouldn't be out much if it sucked.

Competition Electronics ProChrono Digital Chronograph

Thats the model I had my eye on in my Sinclair's catalog last night, looks good to me, thanks again!

 

[JGorski]

OK, OK, I bought one! Tripod, too.
Amazon.com: Competition Electronics ProChrono Digital Chronograph: Sports & Outdoors
Amazon.com: Vista Explorer 60-Inch Lightweight Tripod with Tripod Bag: Camera & Photo