Why start with .015 off?

[Mark611]

Thank you, Bill, but how much IYOP should I back my powder charge off? Treat me as tho I know nothing?

 

[Bill Norris]

Thank you, Bill, but how much IYOP should I back my powder charge off? Treat me as tho I know nothing?

Personally, I would back off at least two full grains if I were jamming any bullet in any case period. Especially if you know you are already at the top of the charge window.

 

[BoydAllen]

For sure, I do use the Wheeler video method. I was just bringing up that other method for discussion about those that jam the bullet in with bolt close plus .020 just to make comprehension of actually where they have the bullet setting in the lands.

What I recommend is coming up with the distance between touch and jam, which will vary quite a bit depending on the shape of the bullet. That way you know where you are within that range.

 

[JB10]

I have found with me it all depends. For instance one of my 6.5 Creedmoors i use 140 berger vld hunting bullet. The very first seating depth i tested was .020 off. I got a wild hair to test a different ddepth.found it shot slightly better touching lands. Another 6.5 creed i use 140 elm. It did not like touching lands, it liked .020 off. I like to start at .020 off and find a powder charge that stands out, then adjust depth if needed.

 

[dcali]

Consider the source. Berger isn't catering to the extreme accuracy crowd with this. I would take it with a grain of salt. A more common approach is to jam and work backwards. I've found that this method, when followed exactly produces random noise, not good results. There aren't any shortcuts to finding the optimum seating depth when you're aiming for benchrest/f class levels of accuracy.

 

[BoydAllen]

I have a question about loading at jam? Because I have never done that! I normally load off jam, Let's say I want to load at jam for my 6.5CM, my normal load for now is 41gns of RL16, using a 147gn Hornady ELDM which is not a max load, but book data says it's not far off, where should I start? somebody give me a run down on how to proceed! I have been very curious about how I go about doing this?

I have a question for you. What EXACTLY do you mean when you say you want to try loading at jam? How do you define jam?

 

[JFrank]

How a person defines jam only matters if that person is sharing or receiving information.

Now if we could only get everyone to agree on what jam is.

 

[CharlieNC]

The Berger method which is being questioned is a screening method using coarse increments across an extremely wide range, only used to identify the starting point for fine tuning. It's a generic approach for all types of shooting.

 

[powderbrake]

I like to use the Wheeler method to determine "Touch". This is when you are just touching the lands. I find this method corresponds very closely to the results I get with a Hornady seating gage. "Jam" is deeper into the bore, and can be any length into the bore, depending on how tight the neck is on the bullet.

I like to start load development at "Touch", and adjust powder to smallest group. I generally start the powder a grain or two below what my experience with that caliber and bullet weight has shot previously. Then I change seating depth to move deeper into the bore in +.003 increments to find the smallest group. This seems to occur at about +.006 to + ,010 for most loads. The + signifying it is deeper into the bore, i.e. seated farther out of the case from touch. These are not "jammed" so deep that they will pull the bullet if you have to open the bolt on an unfired found.

I stopped even checking "Jump" because seating at Touch + seems to always work. Even my 6BR with Berger 105 hybrids I seat at Touch +.010.

 

[Mark611]

Thank you for your response PB,

 

[Mark611]

boyd, I am not an expert, I use my Hornady OAL gage and a modified case, I have pushed some bullets into the barrel to the point where I have to use a rod to push them back out, I have also pushed bullets to where they just lightly stop and come out by just removing the set up, I have tried to get the same measurements or consistent measurement and record these measurements to get a good idea of what I think is a safe point of stoppage, I have started my seating depths from there, as I have said I take that measurement and back off my seating depth until I see my accuracy node or nodes and certain depths, this is why I want to understand how seating depth into the lands or just touching the land work???

 

[Rat Rifle]

I am not am expert either. But this answer is very simple. And it has already been stated in this thread. Within reason, You have found “TOUCH”. You have worked outward, and presumably found some accurate nodes. Now, if You want to, You can go from “TOUCH” further into the lands .003” at a time, until You find a node In The Lands. Only the target can tell what is best. You should find this good node well short of ”Jam”. Jam is not a good place to be.

This is how I see it, and I hope it helps

 

[Mark611]

Rat I agree!