ES and SD on target with the 30BR

[Kevin1990]

So I had two different charge weights for my 30BR. Using 34.5gr and 34.7gr of N130.

I loaded 20 rounds up with 34.7gr, the night before. Then my father wanted to come to the range with me to sight in his hunting rifle. I never get to shoot with him, so I loaded up another 20 rounds with 34.5gr just to see what kind of velocity increases I would see with .2gr increase, if any.

Long story short the 34.7gr charge had a higher ES and SD but continually agged better on 2 different occasions including today compared to the 34.5gr charge. However, when I shot groups on those occasions 34.7gr had the largest single group each time. (Possibly shooter error.) Below are the numbers. Do you generally ignore what the Chrono tells you in a situation like this?

I was also surprised at the velocity increase off of .2gr. I'm using a RCBS charge master lite, so I'm not sure how accurate it is. Either way, it was a nice little experiment and a good time with my Dad.

N130 34.5gr
ES 23
SD 7.0
AVG: 3,015fps

N130 34.7
ES 27
SD 8.0
AVG 3,032

 

[ballisticdaddy]

I try to balance the data from the chronograph with the group size and shape, the shooter needs to be able to trust the target. When we do a OCW test we usually see somewhere in the range of 15-20 fps increase with a .2 to .3 grain increment. My best loads are generally not showing the best chronograph numbers but print bugholes on target. Sounds like great time to bond with your dad....hope you repeat and enjoy!

 

[Kevin1990]

I try to balance the data from the chronograph with the group size and shape, the shooter needs to be able to trust the target. When we do a OCW test we usually see somewhere in the range of 15-20 fps increase with a .2 to .3 grain increment. My best loads are generally not showing the best chronograph numbers but print bugholes on target. Sounds like great time to bond with your dad....hope you repeat and enjoy!

Thanks for the confirmation! I wasn't sure what a normal increase in velocity would be. I just got the chronograph a few months back and started using it these past few weeks. Really eye opening, especially on my father's .270 with factory ammo.

 

[Straightshooter1]

So I had two different charge weights for my 30BR. Using 34.5gr and 34.7gr of N130.

I loaded 20 rounds up with 34.7gr, the night before. Then my father wanted to come to the range with me to sight in his hunting rifle. I never get to shoot with him, so I loaded up another 20 rounds with 34.5gr just to see what kind of velocity increases I would see with .2gr increase, if any.

Long story short the 34.7gr charge had a higher ES and SD but continually agged better on 2 different occasions including today compared to the 34.5gr charge. However, when I shot groups on those occasions 34.7gr had the largest single group each time. (Possibly shooter error.) Below are the numbers. Do you generally ignore what the Chrono tells you in a situation like this?

I was also surprised at the velocity increase off of .2gr. I'm using a RCBS charge master lite, so I'm not sure how accurate it is. Either way, it was a nice little experiment and a good time with my Dad.

N130 34.5gr
ES 23
SD 7.0
AVG: 3,015fps

N130 34.7
ES 27
SD 8.0
AVG 3,032

For the most part. . . yes, I ignore my chrono data when developing a load and looking at my groupings. What's I've seen in my data that I've collected over the years is that the best chrono numbers seldom corelates to the best groupings. Certainly, poor chrono numbers will not result in good groupings, but the focus for determining the best load is what you can consistently get on target. IMHO, the best use of chrono numbers is to quantify just how well you're loading your cartridges and the velocity info is good for LR shooting where it's good to put that chrono data into one's ballistic apps for a good firing solution.

Your chrono number are decent, though without number of shots taken, can't be sure just how valid they might be.

 

[NZ_Fclass]

N130 34.7
ES 27
SD 8.0
AVG 3,032

So - 3032fps +/- 13.5fps. Not a lot to worry about. Probably 1 kernel of powder, or a gnat's of neck tension.
Put the higher and lower figures into ballistic software - I doubt there will be much difference.

 

[Kevin1990]

For the most part. . . yes, I ignore my chrono data when developing a load and looking at my groupings. What's I've seen in my data that I've collected over the years is that the best chrono numbers seldom corelates to the best groupings. Certainly, poor chrono numbers will not result in good groupings, but the focus for determining the best load is what you can consistently get on target. IMHO, the best use of chrono numbers is to quantify just how well you're loading your cartridges and the velocity info is good for LR shooting where it's good to put that chrono data into one's ballistic apps for a good firing solution.

Your chrono number are decent, though without number of shots taken, can't be sure just how valid they might be.

I always forget to put information in my posts! I shot 20 shots of each charge weight for this go around.

 

[Kevin1990]

@Forum Boss I put this question in the wrong place. meant to put it in the reloading forum.

 

[jackieschmidt]

I know my way around the 30BR pretty well, and all I use a Chronograph for is ascertaining the velocity of a given load.
At the distance I shoot, 100 and 200 yard VFS, SD and ES are a non issue as long as the rifle is agging at a competitive level.

 

[Kevin1990]

I know my way around the 30BR pretty well, and all I use a Chronograph for is ascertaining the velocity of a given load.
At the distance I shoot, 100 and 200 yard VFS, SD and ES are a non issue as long as the rifle is agging at a competitive level.

Good to know, Jackie!

 

[209jones]

Seems to me with a decent SD like that, I might look at seating depth, or neck tension consistency, possibly even check if neck shoots better carboned or clean inside as to getting the ES down.

 

[Kevin1990]

Seems to me with a decent SD like that, I might look at seating depth, or neck tension consistency, possibly even check if neck shoots better carboned or clean inside as to getting the ES down.

seating depth test will be next. then I have a few bushings im going to try and mess around with. Things look good, but hopefully I will be able to tighten things up a little more.

 

[jackieschmidt]

seating depth test will be next. then I have a few bushings im going to try and mess around with. Things look good, but hopefully I will be able to tighten things up a little more.

Kevin, you have not indicated what your primary purpose is for your 30BR.
If it is to shoot either informal Club Matches or Registered Matches, you want the rifle “Agg” want at it’s very best. That means shooting the smallest groups and disregarding ES and SD.

Sure, it is satisfying to actually have low numbers when you hit that sweet spot, but in Short Range Benchrest Tuning, that is often not the case.

Your velocity is about right, I shoot at an average 3050fps with my own 112 grn bullet. That is shooting 35.5 grins of N-130.

Seating depth is VERY important in the 30BR. It is difficult to say exactly what is ideal, but suffice to say, when you find it, you will know it.

My bullet/barrel/reamer combination likes a little “jump“, probably around .010. And you have to believe that is pretty much carved in stone, and I will not change that unless things get so bad that I look up and see “The Four Horseman Of The Apocalypse “ coming over the Burm.

 

[Kevin1990]

Kevin, you have not indicated what your primary purpose is for your 30BR.
If it is to shoot either informal Club Matches or Registered Matches, you want the rifle “Agg” want at it’s very best. That means shooting the smallest groups and disregarding ES and SD.

Sure, it is satisfying to actually have low numbers when you hit that sweet spot, but in Short Range Benchrest Tuning, that is often not the case.

Your velocity is about right, I shoot at an average 3050fps with my own 112 grn bullet. That is shooting 35.5 grins of N-130.

Seating depth is VERY important in the 30BR. It is difficult to say exactly what is ideal, but suffice to say, when you find it, you will know it.

My bullet/barrel/reamer combination likes a little “jump“, probably around .010. And you have to believe that is pretty much carved in stone, and I will not change that unless things get so bad that I look up and see “The Four Horseman Of The Apocalypse “ coming over the Burm.

Primary purpose for this one is informal competition. Some local club matches that happen monthly at 100 and 200 yards. That's interesting, I was always under the impression from watching videos that low ES and SD almost always correlated with what would most likely be the smallest groups. Right now I'm jammed pretty hard, so I'll start backing off in small increments and see what happens.

It's the most accurate gun I've ever shot. When doing powder charges all of them looked pretty darn good. So hopefully I'll get a clear picture like you speak of when testing seating depth and I can see where it opens up and where it's small and happy.

 

[jimmymac]

I haven’t read through all this but IMO, ES and SD are white noise in a 30BR shooting 30BR distances. Find a seating depth and powder charge that consistently produces small groups and call it done.

If you are having a hard time determining what load combo is shooting best, do more testing at 200 yards being diligent about your wind flags. You will figure it out in short order.