Post by: JimmyHoffa on September 28, 2015, 05:40:02 PM
Reading the powder can/reload manuals/mfg websites, I thought I would be pretty close to published velocities. But the chrono was either surprisingly low or high. The loads were pretty consistent amongst themselves.
One example was 30-06 I was hoping to get around 2600 fps, but everything read about 2250 fps. (the dang .30-30 can do that) So next batch gets a few more grains. The other example was .338-378. Expected to get about 2850, chrono is saying 3050. And the charge was less than max published which had even lower velocity.
Just kind of curious how closely your results match your predictions.
Post by: jasnt on September 28, 2015, 09:32:09 PM
Post by: JimmyHoffa on September 28, 2015, 09:53:37 PM
Within a 100 fps, I could've made up some reasonable excuse to convince myself. Chrono was about 12 feet out, so nothing goofy there. Made that mistake long ago.... :chuckle:
Post by: jasnt on September 29, 2015, 06:18:09 AM
Post by: 2labs on September 29, 2015, 06:25:31 AM
Which chrono? I have a digital pro that every once in a while gets just the right light conditions and throws crazy speeds. Last week end for example it said my 243 was shooting a 95 vld at 5016fps. 4996, then it snapped out of it going back to 3100
Those probably even sound different :yike:
Post by: Stein on September 29, 2015, 06:32:01 AM
Post by: headshot5 on September 29, 2015, 06:35:01 AM
Quote
The moderately priced chonos are all wildly inaccurate. Shot the loads out to distance and use calculators with known bc to calculate actual velocities. Most of mine were a couple hundred off.
With how wildly inaccurate ballistic coefficient values are (provided by bullet manufacturers) on most bullets it is hard to say it is just the chrono.
Post by: Bob33 on September 29, 2015, 06:46:55 AM
Post by: theleo on September 29, 2015, 08:09:45 AM
22-26" Same barrel/twist and in a few cases same model. pretty much same atmospherics as book.Powders matter with barrel lengths. If your trying for a heavy bullet using a magnum powder in your 06 with a 22 inch barrel you lose more velocity per inch of missing barrel compared to what the factory used (probably 24" for the 06). Add in that they probably have tighter chamber dimensions on their test barrel than your factory rifle.
Within a 100 fps, I could've made up some reasonable excuse to convince myself. Chrono was about 12 feet out, so nothing goofy there. Made that mistake long ago.... :chuckle:
As for the Weatherby, I'd be checking for pressure signs. It's odd to me for it to be that much higher. If the published data is with a 24" tube I'd say 100 fps increase over published makes sense.
Post by: high country on September 29, 2015, 08:10:01 AM
The moderately priced chonos are all wildly inaccurate. Shot the loads out to distance and use calculators with known bc to calculate actual velocities. Most of mine were a couple hundred off.
Winner.
The reason we chrono loads is for accuracy. When we field validate the load, we don't NEED the bc or the velocity as we now have actual dope to work with. A bc or velocity can be calculated from the results.....and your confidence will be higher.
They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.
Post by: Bob33 on September 29, 2015, 08:22:56 AM
They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
Post by: birddogdad on September 29, 2015, 08:32:27 AM
Post by: JimmyHoffa on September 29, 2015, 10:39:02 AM
No pressure signs at all. 26" (but that shouldn't be more than 20+ fps) When I saw the chrono spit out 3096, I was thinking 'uh,oh...hope I can lift the bolt!' It came up with ease. Calibrate the scale every batch to eliminate that uncertainty.22-26" Same barrel/twist and in a few cases same model. pretty much same atmospherics as book.Powders matter with barrel lengths. If your trying for a heavy bullet using a magnum powder in your 06 with a 22 inch barrel you lose more velocity per inch of missing barrel compared to what the factory used (probably 24" for the 06). Add in that they probably have tighter chamber dimensions on their test barrel than your factory rifle.
Within a 100 fps, I could've made up some reasonable excuse to convince myself. Chrono was about 12 feet out, so nothing goofy there. Made that mistake long ago.... :chuckle:
As for the Weatherby, I'd be checking for pressure signs. It's odd to me for it to be that much higher. If the published data is with a 24" tube I'd say 100 fps increase over published makes sense.
Post by: Stein on September 29, 2015, 11:06:48 AM
QuoteThe moderately priced chonos are all wildly inaccurate. Shot the loads out to distance and use calculators with known bc to calculate actual velocities. Most of mine were a couple hundred off.
With how wildly inaccurate ballistic coefficient values are (provided by bullet manufacturers) on most bullets it is hard to say it is just the chrono.
Look up the G7 values or buy the book, they are incredibly accurate. Don't go by the manufacturer. Even with their numbers, you can reverse calculate the velocity way more accurately than a chrono.
There is absolutely no substitute for taking your final load and shooting it from 50 yards to however far you can and base the drop charts off of that. Everything else is guessing.
Post by: headshot5 on September 29, 2015, 11:42:19 AM
Quote
Look up the G7 values or buy the book, they are incredibly accurate. Don't go by the manufacturer. Even with their numbers, you can reverse calculate the velocity way more accurately than a chrono.
There is absolutely no substitute for taking your final load and shooting it from 50 yards to however far you can and base the drop charts off of that. Everything else is guessing.
LOL,
I was just pointing out that there are more factors than just the chrono. I don't get too worked up over velocity, I go for accuracy and build all my drop charts based on shooting those distances The way this thread makes it sound, chronographs are the most worthless thing since the snuggie.
Post by: high country on September 29, 2015, 08:07:35 PM
They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.
Post by: jasnt on September 29, 2015, 08:47:39 PM
They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.
They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.
why would any one sight in 3"high at 100 :dunno: if you want to be zero at 250 then zero at 250. Seems to me that would leave a lot of uncertainty like the up hill 175They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.
Post by: crabcreekhunter on September 30, 2015, 01:17:56 AM
Post by: Stein on September 30, 2015, 12:13:55 PM
I spent a ton of time at the range and reloading bench, $30 on a turret sticker and now shoot anything from zero out to max range with absolute confidence.
Post by: Bob33 on September 30, 2015, 12:43:56 PM
Most shooters sight in at 100 yards because most ranges are 100 yards. There are few 250 yard ranges although it would be advantageous to test loads at longer distances than 100.They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.why would any one sight in 3"high at 100 :dunno: if you want to be zero at 250 then zero at 250. Seems to me that would leave a lot of uncertainty like the up hill 175They're nice for load development, but at the end of the day 200 fps won't make any difference unless you need a vectronix range finder.At 400 yards the difference between 2600 fps and 2400 fps (with a 3" high zero at 100 yds) is about 8 inches. I'd be concerned about that. :twocents:
But it's a known value. If you're a holder over guy.....shoot a 338 edge, if you're a dope and twist guy.....it matters very little.
3" high introduces a lot of problems for people.....like the 175 yard slightly uphill shot.
Post by: crabcreekhunter on September 30, 2015, 01:04:46 PM
Post by: lamrith on September 30, 2015, 03:21:08 PM
It really comes down to how one hunts and knowing their weapon which dictates how they set it up!:yeah: part of zero @ 100 also comes from the glass being used. Some people have BDC glass for their caliber etc and those often call for 100yrd zero to use the holdovers built into the glass.
Post by: JJB11B on September 30, 2015, 03:27:52 PM