Unknown Munitions for the 270 WSM

[Unknown Munitions]

Time to play with seating depth on load #9

I agree that a seating depth ladder on string #9 would make sense, but the variation in velocity data collected has me worried about the accuracy of the chonograph. I would love to test these loads across another chronograph to validate the data before pursuing the load development any further.

 

[Unknown Munitions]

How much difference do you normally see off data collected from 3 shots vs say 10? I take it your just looking for a trend across a .2 or .3 grain spread?

I’m curious because I have chased some dead ends on looking at a small sample size. Groups 3 and 4 are a perfect example of this, I would bet that group 3 wouldn’t repeat over a 10 shot test.

When I chrono 10 shots of the same load I can almost always cherry pick the data and find 3 that have single digit ES, but the 10 shot Es shows 70+ but if I picked the “right” 3 out of the box and shot them I could have a ES of 6.

Not saying it’s happening here because groups 9 and 10 show a good trend across 6 shots with a .2 grain spread and 30 FPS between them, but I would want to see a bigger sample before I started chasing them.

I guess IME 3 shot Es testing is about like shooting 3 shot groups.


Sent from my iPhone using Tapatalk

I agree that 3 shot sample size can have its shortcomings, however this data across several tests can start to paint a picture and help to narrow down on a velocity node. With graphs calculating velocity gain per string, +/-1 and 2 standard deviations and trend lines, you can visualize the data in a way not normally noticed with numbers simply written on a piece of paper. With the right bullet jump, almost any group can be tightened up but we need the tight ES/SD to maintain vertical dispersion at distance.

 

[doverpack12]

I agree that 3 shot sample size can have its shortcomings, however this data across several tests can start to paint a picture and help to narrow down on a velocity node. With graphs calculating velocity gain per string, +/-1 and 2 standard deviations and trend lines, you can visualize the data in a way not normally noticed with numbers simply written on a piece of paper. With the right bullet jump, almost any group can be tightened up but we need the tight ES/SD to maintain vertical dispersion at distance.

Do you see ES vary some as you perform the seating depth test. I ran one today with my best powder charge at 1 ES but bad group and watched ES grow then shrink back to 1 with a good group as I seated deeper.

 

[Unknown Munitions]

Do you see ES vary some as you perform the seating depth test. I ran one today with my best powder charge at 1 ES but bad group and watched ES grow then shrink back to 1 with a good group as I seated deeper.

Normally when you are in the lands is the only time the ES will really open up if you are sitting in a node.

 

[Ryan Avery]

I agree that 3 shot sample size can have its shortcomings, however this data across several tests can start to paint a picture and help to narrow down on a velocity node. With graphs calculating velocity gain per string, +/-1 and 2 standard deviations and trend lines, you can visualize the data in a way not normally noticed with numbers simply written on a piece of paper. With the right bullet jump, almost any group can be tightened up but we need the tight ES/SD to maintain vertical dispersion at distance.

I would agree with this @robby denying. After shooting his reloads for the past couple of months it's highly unlikely the ES is that big. Those chrony's are not to be trusted.

 

[PNWGATOR]

Is his crony similar to his Ford?

 

[Cahunter805]

Definitely need a new chrony Robby! Looks like some misreads for sure. Look at load 4 for an example. I’ve never witnessed a jump of 100fps especially with the quality components in the loads you were shooting. The first 2 shots look more what I’d expect.
Jake
This seems more of an OCW test than a ladder though?

 

[BuckSnort]

Robby come to the dark side and start twisting turrets

 

[HuntHarder]

Those Damn Chrony's!!!! I had one get me a couple years ago. I had to drive an hour to shoot, not to mention all the time I had in reloading. Started shooting and did not realize I had a problem until 10 rounds in. I was so pissed, that I set the chrony up at 50 yards and proceeded to go full "Office Space" on that MF'er.

 

[gbflyer]

I shot my Chrony one day. Best thing I ever did. I prefer a magnetospeed for load development then use Pro Chrono when I don’t want the transducer hanging on the barrel effecting the POI

 

[Blaw]

gonna be watching this one as I am at the same place in my load development as well

Is there a big difference in doing the 2 shots per load vs the 3 shots? Or do you get enough of a sample to see which ones are more promising with either? 3 shots I would assume is just a bit more thorough?
@Unknown Munitions

 

[robby denning]

Hey, I’ll do whatever needs done, but first, if my Chrony is crap or defective, let’s start there first.

Should I just buy a new one? What do you suggest?

And if I ship my rifle, do I need to go through an FFL? My guy (and all the shops) are shut down for a while so that could be weeks.


Sent from my iPhone using Tapatalk

 

[tdhanses]

Hey, I’ll do whatever needs done, but first, if my Chrony is crap or defective, let’s start there first.

Should I just buy a new one? What do you suggest?

And if I ship my rifle, do I need to go through an FFL? My guy (and all the shops) are shut down for a while so that could be weeks.


Sent from my iPhone using Tapatalk

Should not need to go through an FFL to ship your rifle, magneto speed is my suggestion for a chrono, I have the sporter model and it does the job just fine and won’t break the bank.

 

[robby denning]

Should not need to go through an FFL to ship your rifle, magneto speed is my suggestion for a chrono, I have the sporter model and it does the job just fine and won’t break the bank.

Thanks for the clarification Tim, I can never remember how FFL works. Just got off the phone with Jake, we’re going to go the new chrono route. Ryan’s shipping his Magneto Speed Sporter (I believe that’s what you referenced) and Jake’s sending another ladder test

If it turns out my Chrony is the problem, I’ve got a sweet deal for someone

Thanks man.


Sent from my iPhone using Tapatalk

 

[Cahunter805]

Robby
It’s more than likely that old chrony.
Throw a new battery in it and set it up about 10-12ft from the muzzle.
Then attach the magnetospeed and shoot through both. Will give you an idea what’s going on for sure.

 

[robby denning]

Robby
It’s more than likely that old chrony.
Throw a new battery in it and set it up about 10-12ft from the muzzle.
Then attach the magnetospeed and shoot through both. Will give you an idea what’s going on for sure.

That's a great idea, didn't think of comparing it to the Magnetospeed simultaneously

 

[Chad E]

That's a great idea, didn't think of comparing it to the Magnetospeed simultaneously

Having done this myself with a cheap conventional chrono that was giving readings that did not make sense compared to shooting at distance I found much more accurate and believeable readings from the magnetospeed. I think if you do it this way itll paint a much clearer picture of what's going on.

 

[robby denning]

Having done this myself with a cheap conventional chrono that was giving readings that did not make sense compared to shooting at distance I found much more accurate and believeable readings from the magnetospeed. I think if you do it this way itll paint a much clearer picture of what's going on.

I'm gonna do it then. It'd be great to know.

 

[Unknown Munitions]

I'm looking forward to having duplicate data to verify the velocities, now we just need to get the rifle on a bipod and rear bag and single feed those bad boys for the best data results!

 

[robby denning]

I'm looking forward to having duplicate data to verify the velocities, now we just need to get the rifle on a bipod and rear bag and single feed those bad boys for the best data results!

me too, but to be clear, I don't have a bipod, but am shooting a front bag and rear bag. Will that roll with what you're looking for?