Odd fps readings with new rifle loads?

[LanceS4803]

Finally got to try out my new rifle, Mossberg .375 Ruger!
These are the readings from the initial handloads. Using inexpensive bullets to get a feel for actual velocities and get used to the rifle.
Accurate 5744 powder, Fed 215 magnum primers and Speer 235gr SP.
I noticed that at each weight I had one really weird outlyer. All loads individually weighed on digital scale with powder trickler. Load data from Accurate for Low, Mid and Max loads. Initial accuracy was fine, with groupings around 2" at 100yds.
Any thoughts on what caused this?

40 gr- avg 1977, ext spread 167 (take out the * outlyer and the spread is only 31)
1990
1854 *
2021
2008
2012

48gr - avg 2334, ext spread of 173 (minus * outlyer, spread was 33)
2314
2282
2455 *
2306
2315

55gr - avg 2566, ext spread 142 (minus *, spread was 15)
2585
2600
2590
2597
2458 *

 

[Omega]

What kind of Chronograph where you using?

 

[LanceS4803]

Shooting Chrony F-1

 

[infoman jr.]

If you've carefully controlled the inputs, I'd blame the chrono.

 

[Omega]

Could be the chrony, but there are a few other reasons that it can be as well. First, projectiles; some variance such as weight (a 1/2 grain), tip deformity etc, second, brass how many times fired, head stamp, neck annealed, neck tension etc. If it is constantly one outlier, then I'd lean more toward the chrony than the bullets.

 

[LanceS4803]

Sounds good. Excuse to buy a new chrono?
NIB brass, so that eliminates quite a few variables.

 

[DaveB]

Do you have a beam scale? I do not own a digital scale so I don't know the routine to follow when you first set it up.

You are getting (just) one outlier per group and the variance is too large unless as noted your bullet quality is suspect.

If you have a scale simply weigh each charge from the digital process and eliminate or identify the source of the outliers. I would not be surprised if it was the first shot of each group.

This is why I number each round--I have a blank target on my bench and shot one is labeled 1, etc. I can make notes like FL (I flinched or pulled) I hate forgetting which shot or shots I screwed up on.

 

[LanceS4803]

I do have a beam scale, but use a PACT digital scale. It has a set of brass weights to calibrate each time it is turn on or moved.
Those shots are listed in order of being fired.
I checked bullet weights tonight, all are good.
Must be the chrono, which has many, many years of use.

 

[Deer Assassin]

bad powder

i had some 5744 once that was bad it made my fps go crazy

i do not like that powder at all

all though i have another lot that is just fine

 

[jlanecr500]

bad powder

i had some 5744 once that was bad it made my fps go crazy

i do not like that powder at all

all though i have another lot that is just fine

X2

I'll never use it again. High dollar fertilizer

 

[LanceS4803]

Interesting.
I got the 5744 to use for reduced-loads. Their tech support was really helpful is providing load data for different bullet weights and velocities, low to full power.
I do have other powders that I will be trying.

 

[mr.big]

was the chronie set up in direct sunlight or under powerlines,,,,,both caused me problems in the past,,especially under powerlines

 

[LanceS4803]

It was sunny, but 0800 in the morning, so really low angle sun.. I also had the sun screens over the top.

 

[jlanecr500]

Reduced loads can be tricky. Some use fillers to get the case fill value up into the 90's. If your case fill isn't in the mid to upper 90% range, strange things can occur such as: fps swings, hang fires, misfires. I have used over powder wads with great success in keeping the powder on the primer.

AA5744 is double based which has 20% nitro. Nitro tends to burn hotter/faster as the temps drop because it crystallizes in cold temps. I experienced 6 inch poi changes from 30 to 40 degrees F.

What bullet and velocity are you looking for? I can run some loads in QL if you want.

 

[LanceS4803]

6" shift with only 10 degrees difference? Wow, that would never work out west (or here in the south, even).

5744 is supposed to be good for reduced. THe load info they gave me matches pretty close to what I was achieving.
I was just looking for lower power loads to get used to the rifle. The 375 can have a hefty recoil, but this one isn't bad. I hit my target rifle weight right at 9lbs, with rifle, mount and scope, which is perfect.
I'll probably use lower power on whitetail and just getting more familiar with the rifle.
I have yet to try full power with 250gr or 300gr, so we will see, but for now it does not recoil as much as my .45-70, and NO WHERE near what the 3 1/2 magnum turkey loads do.

 

[jlanecr500]

6" shift with only 10 degrees difference? Wow, that would never work out west (or here in the south, even).

5744 is supposed to be good for reduced. THe load info they gave me matches pretty close to what I was achieving.
I was just looking for lower power loads to get used to the rifle. The 375 can have a hefty recoil, but this one isn't bad. I hit my target rifle weight right at 9lbs, with rifle, mount and scope, which is perfect.
I'll probably use lower power on whitetail and just getting more familiar with the rifle.
I have yet to try full power with 250gr or 300gr, so we will see, but for now it does not recoil as much as my .45-70, and NO WHERE near what the 3 1/2 magnum turkey loads do.

I have a couple 40 caliber smokeless muzzleloader. The one I use for target (14lb) has a brake but the other one I use for hunting (11lb) doesnt. I typically shoot 300gr bullets at 2800 to 3200fps with pretty hefty charges (well over 100gr). Without a brake, you need as much eye relief as possible. Luckily, Kyle Pittman of Pittman bullets has developed jacketed high bc projectiles from 225gr to 325gr. I can drop to 225gr at 2800fps and be quite comfortable. Like the 3.5" Turkey loads, you won't notice it when you make the kill.
Enjoy....Bigger is better.