Fast chronograph readings

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mistahmojoryan

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I've been loading 70gr with 250gr bullets and didn't have any pressure concerns/signs. I got the 70gr max from the Hornady 8th ed. I recently chronographed that load and got an average of 2850fps which faster than the Lee or Hornady manuals indicate it should be. This is only from a 22" barrel. Am curious what the latest Hornady manual lists for a max with H4350 and 250gr bullets if anyone can share. Was also shooting my 308Win with BL-C2 and was getting 100-150fps faster readings than listed velocities and those 2 loads weren't even close to the lands.

That was my first time out with a chronograph. The four loads I measured (from 2 rifles) were all loaded max or close to max and faster than published velocities (100-250fps). Maybe it's an issue with the chronograph, I don't know, but I've decided to back off the powder charges and work up to 'normal' velocities. Since I'm pretty new to reloading and chronographs I was hoping to get some feedback from others experiences.
 
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In my opinion Hornady is not kind to Hodgdon. I love Hornady bullets, but I'm starting to hate their manual. That being said. It looks to me that your vel are showing high on the Cronograph. I would try another Chronograph if possible. What model is it?

George
 
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mistahmojoryan said:
I've been loading 70gr with 250gr bullets and didn't have any pressure concerns/signs. I got the 70gr max from the Hornady 8th ed. I recently chronographed that load and got an average of 2850fps which faster than the Lee or Hornady manuals indicate it should be. This is only from a 22" barrel. Am curious what the latest Hornady manual lists for a max with H4350 and 250gr bullets if anyone can share. Was also shooting my 308Win with BL-C2 and was getting 100-150fps faster readings than listed velocities and those 2 loads weren't even close to the lands.

That was my first time out with a chronograph. The four loads I measured (from 2 rifles) were all loaded max or close to max and faster than published velocities (100-250fps). Maybe it's an issue with the chronograph, I don't know, but I've decided to back off the powder charges and work up to 'normal' velocities. Since I'm pretty new to reloading and chronographs I was hoping to get some feedback from others experiences.
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what caliber rifle? What brand rifle? What kind/model of chrono?? Are you shooting a .338wm??
 
Checking new chrono with say a .22LR is a useful technique.

Also keep in mind that if you're too close to the chrono the muzzle blast can give you wrong readings,
especially with large volume rifle cartridges.

Chrono can be a tricky tool for working up max loadings.
 
To specify, I was shooting a Sako 75 338WM, 22" barrel with 250gr IL's with 70gr of H4350 and ave. 2850fps; same rifle with 210 gr TSX's and 72gr H4350 for 3100fps. Both loads .015 off the lands.
Second rifle is a Winchester 88 in 308- 48gr BL-C2 with 150gr Bronze Points ave. 2930; same rifle with 47gr BLC2 150gr GMX's ave. 3000fps. Both loads are way off the lands in order to fit rounds in magazine.

I'm using a Chrony F-1. Had it 10 feet away from muzzle but I believe that is a recommended minimum so I'll move it further next time and try some 22lr rounds.
 
Light is a big deal with chronys , I find a cloudy day best, the other day in the sun it said my swede sent a 140 grain at 5440 fps. Imagine if that were true.. If it is a cloudy day, and you have wiped the dust away from the sensors with a q tip, I don' use the diffusers when it is cloudy, I try to shoot about 6" over it, I put the rods in it so I know where to shoot...they can. Be very consistent.mi have had 3 of them, they all worked well, the first two died in hunting accidents.
 
Make sure it's folded down completely flat. If not, it makes the sensors closer together and will result in higher than actual readings.
 
When I first got my Master Alfa Chrony I set it up behind buddies Chronograph to compare. Mine would read about 30 fps less than his. Good way to remove any doubt as to your cronographs performance.

George
 
10ft away? That was exactly the same prob i had when shooting 300wsm and 325 wsm - the muzzle blast gave me weird readings (imagine the look on my face when the 200gr accubond gave me a reading of 3200fps when it should have read 2950!) - i had to move it 15-18 ft away to get true readings. As mentioned, verify with a 22LR at 1250fps.
 
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