Why start with .015 off?

[Kracken McGraw]

How far in from touch do y’all think the full square marks take place on the bullet that is pushed in the lands?

 

[Old Navy]

I think that is the third version from Berger.

 

[marchx]

Hybrids are supposed to be jump tolerate.
Hasn't been my experience though. Some do, some don't. 300 grain otm in my 338Imp like a little jam, 140 hybrids in my old 6.5x46 liked .030 off. My BR liked the the 105 Hybrids. 012 off. Gotta test.

I can 100% confirm your experience with 140s and 105s!

 

[Dusty Stevens]

How far in from touch do y’all think the full square marks take place on the bullet that is pushed in the lands?

Could be .050 or even more according to throat shape and bullet shape. Also according to neck tension itll go in farther

 

[Mark611]

Some good replies here, I do not shoot these types of bullets, but I will use my 6.5mm ELDM's as a reference, when I started loading them I started off at 20k off jam, then 15k then 10k, didn't get the accuracy I was looking for, then I went back to 20k and started working down 3k in depth, I found a node at 29k off jam, just for kix I loaded some at 17k off jam and found a node there as well, using all the same powder charges bullet type brass and primers, from looking at what has been posted it's pretty much the same as what you should do when looking for the jump to the lands JMO

 

[big5ifty]

Optimum for accuracy bullet jump is a function of bullet construction, ogive and leade angle.

Everyone that gives a number is giving a number that works for them on their bullet, it's ogive, and their leade angle.

Most of those people do not know what their leade angle is.

You need to find what works for you, and if you are going to copy someone else's excellent bullet jump results, best copy their bullet and their chamber reamer.

 

[Kracken McGraw]

Could be .050 or even more according to throat shape and bullet shape. Also according to neck tension itll go in farther

So just an assumption of the process of the dummy round loaded long and seating bullet with the bolt fully closed. After doing this and seating the bullet in another .020 deeper this would possibly on a correct chamber for that bullet, would have it set at .030 in the lands from touch.

 

[BoydAllen]

Speaking of jump, here is some reliable data that a friend gave me recently. He shoots long range plates pretty often, and does his own barrels. His go to rifle is a 6 CM with heavy bullets, propelled by H4350. When he was jumping about .020, he saw about .005 throat wear for every 50 rounds, which was his usual round count for a shoot. This was not a one time thing. He set his barrel back several times and it repeated. The last time he set the barrel back, he retuned with the bullets into the rifling, and the throat wear stayed put. In his opinion, based on his careful work and measurement, jumping accelerates throat wear when compared to seating into the lands.

 

[Jeff]

My 6BRAI with 103 VT bullets liked ,20 jam

 

[Bill Norris]

Speaking of jump, here is some reliable data that a friend gave me recently. He shoots long range plates pretty often, and does his own barrels. His go to rifle is a 6 CM with heavy bullets, propelled by H4350. When he was jumping about .020, he saw about .005 throat wear for every 50 rounds, which was his usual round count for a shoot. This was not a one time thing. He set his barrel back several times and it repeated. The last time he set the barrel back, he retuned with the bullets into the rifling, and the throat wear stayed put. In his opinion, based on his careful work and measurement, jumping accelerates throat wear when compared to seating into the lands.

Very interesting Boyd.

 

[Idaho-Lefty]

Speaking of jump, here is some reliable data that a friend gave me recently. He shoots long range plates pretty often, and does his own barrels. His go to rifle is a 6 CM with heavy bullets, propelled by H4350. When he was jumping about .020, he saw about .005 throat wear for every 50 rounds, which was his usual round count for a shoot. This was not a one time thing. He set his barrel back several times and it repeated. The last time he set the barrel back, he retuned with the bullets into the rifling, and the throat wear stayed put. In his opinion, based on his careful work and measurement, jumping accelerates throat wear when compared to seating into the lands.

Both, the 103 gr. ELD-X's and 107 SMK's shoot BEST with, a Lite Jam out of, my 6 XC so, this IS "Good News" to, Me !
I started loading them at, .020 and .040 OFF to, Find "Pressure" and see if "Jump" worked best then, reduced Load 1/2 a grain and Moved,.. OUTward for, "BugHoles" with the 107 SMK's and 1/2" for the Horn 103 gr. Coyote, Load !
Thanks for, the "GOOD News",.. Boyd ! And YES, "This" ( easier on Barrel Throats ) makes, SENSE to, Me

 

[Dusty Stevens]

So just an assumption of the process of the dummy round loaded long and seating bullet with the bolt fully closed. After doing this and seating the bullet in another .020 deeper this would possibly on a correct chamber for that bullet, would have it set at .030 in the lands from touch.

No youd need to actually find the lands to know for sure

 

[TylerFromMS]

Speaking of jump, here is some reliable data that a friend gave me recently. He shoots long range plates pretty often, and does his own barrels. His go to rifle is a 6 CM with heavy bullets, propelled by H4350. When he was jumping about .020, he saw about .005 throat wear for every 50 rounds, which was his usual round count for a shoot. This was not a one time thing. He set his barrel back several times and it repeated. The last time he set the barrel back, he retuned with the bullets into the rifling, and the throat wear stayed put. In his opinion, based on his careful work and measurement, jumping accelerates throat wear when compared to seating into the lands.

That’s interesting for sure. In my experience, it has been the opposite- jam eats throats faster than a jump. Guess I’ll have to test it again.

 

[BoydAllen]

So just an assumption of the process of the dummy round loaded long and seating bullet with the bolt fully closed. After doing this and seating the bullet in another .020 deeper this would possibly on a correct chamber for that bullet, would have it set at .030 in the lands from touch.

IMO way too much assuming and not nearly enough careful measuring. I like Alex Wheeler's method for finding an accurate touch measurement. I suggest that you start from there and then find jam (length bullet is pushed back to when loaded long and chambered) using the same neck tension that you will be loading with, with the inside of the neck in the same condition you normally have when you load. Once you have accurate touch and jam measurements with a bullet, you will know where you are with any seating of that particular bullet.

 

[john 800]

They also want you to shoot 6 shots every.015!!

Better shoot 10 shot groups every .005.

 

[BoydAllen]

How far in from touch do y’all think the full square marks take place on the bullet that is pushed in the lands?

Why ask when you can simply do it and measure. My usual load workup seating is somewhere around .006-.010 into the lands. With that, the marks are shorter than wide, about half as long or less being about right.

 

[Kracken McGraw]

IMO way too much assuming and not nearly enough careful measuring. I like Alex Wheeler's method for finding an accurate touch measurement. I suggest that you start from there and then find jam (length bullet is pushed back to when loaded long and chambered) using the same neck tension that you will be loading with, with the inside of the neck in the same condition you normally have when you load. Once you have accurate touch and jam measurements with a bullet, you will know where you are with any seating of that particular bullet.

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.

 

[Mark611]

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?

 

[Liven The Dream]

.308 12 Twist LH 95 Palma Reamer ?
155 Berger HB .
The Magic number .035 jump .

Dasher 1-7.5 Norma Dasher Reamer
105 Burger HB
The Magic number on or in .005 ?

Like Women just a Little Difference !!!
Life is not easy , nothing is free .

 

[Bill Norris]

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?

As I posted earlier on the first page it pays to back off the charge to app. the middle of the charge weight window to allow for bullet bearing surface length. Watch for pressure signs carefully moving back up.