accuracy in load developement

[trueblue]

Mikecr,
I will do some cold bore groups, and finish sighting my rifle in, then post the results. I am going to drop the charge down a couple of tenths to 83.3gr Retumbo I think . I still feel it is important for me to determine how accurate my load is at distance before moving on . At present I don't see the difference from shooting cold bore groups or warm barrel groups, as long as you sight your rifle in for your cold bore shot after you are done. If there is something I am missing concerning shooting cold bore groups versus warm barrel groups, let me know. As far as determining your cold bore shot, wouldn't it be more important to know you are shooting an accurate rifle before worring about your cold bore shot placement.? That can be dialed in after you get your load done. I will try your suggestion about shooting cold bore groups, but will try and do it in the same shooting session.

 

[trueblue]

nndodd,
As far as neck tension goes, you strive to have equal tension gripping the bullet, so you have consistant release of the bullet when you fire the case.
Uneven bullet release will give you higher velocity spreads and bigger groups on the verticle at longer distances. At least that is my understanding of it.

 

[Mikecr]

At present I don't see the difference from shooting cold bore groups or warm barrel groups, as long as you sight your rifle in for your cold bore shot after you are done.

My suspicions are validated..
A cold bore is different dimensionally from a hot bore. Barrel stresses change, and fowling is different. You can assume away, but I'd group no less than 2hrs/shot, and exactly as you would in the field(off bipod,etc) to see cold barrel accuracy(in group form). And to see if it's simply a matter of dialing in for your gun, or whether work is needed on scope mounting/ballistics,etc. I'd also be shooting across a chronograph, every shot.

It might not be a problem at all for your barrel. But I've seen huge differences in best cold barrel load -vs- best hot barrel load(especially w/regard to ES). I've had only one gun and load combo that truely shot the same either way.

 

[trueblue]

Mikecr,
First, I don't recall saying I assumed anything. Secondly, I am not retired and can take 10 hours to shoot a 5 round group. I am glad your "suspicions" were validated. Whatever that means. All I am looking for is constructive feedback on how to proceed with making my rifle as accurate as I can at longrange.
I don't see the validity in taking so long between shots, when conditions can drastically change , when the point is to see how your rifle groups. I would be interested to know how others go about this process as well. Maybe a short explanation on your load developement process for shooting longrange would be helpfull to me.

 

[RockZ]

trueblue, don't take mikecr's comments as an insult. All he is saying is that the most important thing is that the first shot goes where it is supposed to. And yes it is a cold bore shot.
The only way to validate a load for hunting is to accumulate data on the performance of numerous cold bore shots.


Here's the best method of fine tuning your load at distance to reduce the verticle.
Long-Range Load Development


I use the ladder test and have great results. Just take your time when you shoot the ladder .

To validate those results, I shoot and log cold bore shots each time I go to the range.

After I have determined the best load and fine tuned it with the ladder(don't forget to color your bullets with a sharpie)

I set up a target at the desired range for my case it is 600yds, or I shoot at a 3" steel plate swinging target.

I set up my rifle on a bipod and shoot it like I will in the field. I fire my first shot at the 600yd target and note the results. I bring different rifles and shoot those while the primary one cools.

Once the primary rifle is cool, I'll shoot another cold bore shot at the same target. I may only shoot two or three in one range session and will do the same on other days. Before you know it you will have a cold bore group. Conditions may be different , but you must log those as well. Log conditons like wind,temp etc, but don't forget sky condition, sunny/cloudy? Look for trends.

After feeling good about my cold bore load and poi and shooting cold bore groups on targets on previous outings,now I decided just to shoot the 3" diameter steel swinger.

Last time at the range I unloaded my rifle, looked at the wind, boom the 3" swinger is spinning--good cold bore results.

The ladder test in the link works well and you will be surprised as to the difference in the verticle that you will discover. At 600yds my verticle is only about 1-1.5"

Before the ladder shooting what I thought was the best load the verticle was 2.5"

 

[trueblue]

RockZ,
Thanks for the response. That was the type of imfo I was looking for. I did not take Mikecr's comments as an insult. Just seemed he was coming at it from the end product, and I was asking for imfo on the best way to get there .
I will read the link you posted. My point earlier with Mikecr was that before I start worrying about where my cold bore shot is going, I would like to know I am shooting an accurate load. I have not had time to try his cold bore method over a longer period of time, but when I do, I will see if it makes any difference from what I am doing now, and if not, won't bother with it in the future. I am certainly willing to try knew things, if it makes a difference.

 

[Mikecr]

I would like to know I am shooting an accurate load.

By asserting that your group shooting represents best efforts towards accuracy, You essentially declare conclusion with inquisition.
So you're not really looking for contrast, but validation..

For responses desired, you might ask instead "How can I tighten my LR groups?"

But since you wondered, I follow RockZ's approach pretty much.
While fireforming brass I watch my chrono readings , and pressure signs, for reasonable pressure, velocity, ES and feedback for my QuickLoad powder file. I take a best guess there and do the same varying seating depth.
Then I measure H20 capacity on each case discarding departures from the bulk.
Now I shoot a warm bore ladder(15min/sht), with my best guess again.
Then I either make adjustments for further ladders or venture into cold bore accuracy/ES testing with another best guess.
All the while I'm 'hoping' for a good shooter with adequate -predictable -accuracy.
If it sounds like I don't know what I'm doing, or like it's a crap shoot. You're right.
But keep in mind that to date, not one human understands tuning, or could 'predict' a shooter from squat. Accuracy has to be verified as it really is a crap shoot.

 

[RockZ]

trueblue,
I was fortunate with my 7wsm that I worked up loads for this antelope season.
My warm bore groups and my cold bore shots are very close. In fact they virtually coincide and require no adjustment.

But I think what mikecr was alluding to is that you can't take it for granted.That's why I check them as well. It really doesn't take as long as it seems. If they coincide, it will seem like a waste of time. If they don't, you will be glad you checked.

For shooting at the ranges that most hunters shoot it is not as big of a deal. But for long range it is critical.

Just work up a load that shoots well and shoot a quick ladder.
I found that 69.5gr of H1000 shot well with 175 smk's and 168 vld's .

I wanted to try the 162amaxes so I loaded up 3 each of 68.5,69.5,70.5. 3.105" OAL.
70.5 gr shot a 1.25" group at 565yds. No more ladder testing needed. I know those a big gaps but typically I'll need to shoot another ladder at .5gr increments but I only had 1.25" vertical so I tried the 70.5 again.

I loaded some more at 70.5g and shot them again another day. Ist shot hit the 3" steel plate
Shot a 5 shot group and put 4 of the 5 in 1.5" and lost the 5th for a 2.4" group at 565yds.

 

[trueblue]

RockZ,
read the article, thanks for the lead. At this point I know where my pressure limit is , and will do step 3 of the article. After that, I will sight in for my cold bore shots. I found your responses the most helpful.
Mikecr,
Thank you for your responses, but I must admit they confuse me. In one post you state you would not shoot a group with less than 2 hours between shots, and then in the next post you state that you shoot a warm bore ladder with 15 minutes between shots. I do appreciate you elaborating on your method. It really is not that much different than what I have been doing. I shoot over a chrony to check for ES. I cross reference my velocities with my quikload data, and make adjustments to the data to match.
I have not done the ladder test. What I have done is pick a powder charge and loaded up some rounds and shot groups to try and find the most accurate. So, I will try this ladder method and see if it helps me determine a smaller verticle spread.

 

[RockZ]

trueblue,
Let us know how the ladder works out. For me , with my last two rifles the best groups with the least amount of verticle at 600yds were different loads than the best at 100yds.
I also use quickload and a chrono as well and find a load that groups well, then I'll do the ladder just to work it out at distance.

I look forward to hearing the results.

 

[trueblue]

RockZ
This has been the first wildcat that I have worked with. That was part of the reason for the post. After spending some time on the phone today with Joel Russo, a friend who has helped me learn alot this past year, I am far enough along to just go with shooting 3 shot groups with about 3 different powder charges and see which one is the best. It's a smart man who takes good advise and runs with it. After that, all that will be left to do is some cold bore grouping over a period of time, and call it good.

 

[RockZ]

trueblue,
It looks like you are already shooting good groups with the new Jazz. It looks like a great cartridge and I may try a few versions of that myself in the next year. Maybe a switchbarrel with the 338/300/7mm.

Here's a pic of my 3 shot group after ladder testing from my lightweight 7wsm hunting rifle at 565yds:

 

[trueblue]

Very nice. Congrats.