it seems the more i get into this shooting thing the less i know!! having been doing a lot of shooting over the last 3 months i am finding some weird stuff and was wondering if anyone on the board has any ideas. i have noticed an average velocity spred while shooting several rifles this spring. my 284 normally averages around 2950fps over the last 1 1/2 years, yet this spring i am seeing average velocities from 2900 up to my normal range. i have noticed the same type of spread on my 280 as well. 2 days ago while shooting i was averaging 2960-2970 over 30-40 rounds (with the 280) yet when i shot last night my speeds were in the 2925 range. the temp both days was the same...10-15 oC. ammo was bassically the same temp, rifle was not cleaned. a friend which also shot on exactly the same days and times with his 7 mag noticed the same 40-50 fps speed drop as i did. what gives? i am using a ced chrono , the es and sd numbers are always good, so i know the loads are good. the loads have been shot out to 1000 plus yards so i know the chrono numbers are accurate, as the drops line up with the speeds i am getting. i have mega amounts of chrono data and i have been noticing this. all the rifles wear custom barrels so you can eliminate that from the equation, as well the groupings are just as accurate every time out. does anyone have any thoughts? does the barometric pressure or other atmospherics play into the muzzle velocities somehow? i should add the powders are h4831 and h1000, all the same lots, they are normally quite stable. ideas anyone??
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internal ballistics
- Thread starter bingo1010
- Start date
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
1/2 of 1% error is typical in the clocks used in chronies. The CED is are supposed to be more consistent but they have it.
Certainly better then the Chronie brand.
Ambient light is the next largest variable affecting chronies. Why big dollar chronies use acoustic screens.
As long as accuracy is the same, drop charts are the same, pressures are the same, keep the chronie data to ensure you are not trying to blow yourself up.
Beyond that, holes in paper is what I am after.
Jerry
Certainly better then the Chronie brand.
Ambient light is the next largest variable affecting chronies. Why big dollar chronies use acoustic screens.
As long as accuracy is the same, drop charts are the same, pressures are the same, keep the chronie data to ensure you are not trying to blow yourself up.
Beyond that, holes in paper is what I am after.
Jerry
Chrony distance? Just an idea. Like myself I see differences in fps but I am more looking for consistancy in loads. I am sure my day to day differences can be associated to my chrony distance from the muzzle. I do not measure. As long as it's lined up and centred and level I shoot.
