"Just off the lands"?

[Mountain Man]

So I'm doing the dummy round process with my new 260R barrel and it seems one of the lands extends further than the other 5. I'm trying to achieve the mythical .010-.015" jump associated with ELD bullets using the sharpie technique but I'm down to 2.76" and there is still one land that is barely touching the ogive.

Should I use this as the basis for the jump or where all 6 lands are touching?

Sent from my SM-S820L using Tapatalk

[bigedp51]

Question?

Are you full length resizing or neck sizing and have you measured bullet runout?

Meaning is it a bur on the rifling or runout causing the bullet to not touch all the rifling.

Or don't worry about it and shoot some cheaper bullets to break the barrel in and smooth up the throat. (And then chase the lands)

[Mountain Man]

I haven't fired it yet. I'm using fl resized 7-08 brass.

Run out is a possibility. Talking about really light marks on the bullet.

Sent from my SM-S820L using Tapatalk

[Zero333]

Here is a video on how to find the rifling, and this method works very nicely and it's one I like the most.
https://www.youtube.com/watch?v=TWmIwPwLyyg

and another method video....
https://www.youtube.com/watch?v=GmDi7v530Og&t=569s

I also recommend getting a bullet comparator to get a reliable / repeatable measurement.

If you use the method like on the video, I must add that once you find the measurement to the lands and set up the seating die to that measurement, pay no attention to any small variation of length of the COAL.
The seating die (if it's been made in the past 10 years) will ensure that the cartridge base to bullet ogive is consistent.
Meaning that the Open Tip Match bullets will vary in length because their tips are not 100% identical, but the seating die will make sure the measurement from cartridge base to bullet ogive is the same. And that's what really matters.
The plastic tipped bullets are more consistent in length so the COAL will not vary very much after seating them.

There are tools made to measure the bullet jump to the rifling. Tools like the Hornady AOL.

[Mountain Man]

Wilco!

I had to cut the nut off my donor receiver so I'm doing all this work with sharpie marks on the barrel and receiver at the correct head spacing. The first video seems to make the most sense for my current application so I'll give it a shot!

Sent from my SM-S820L using Tapatalk

[Mountain Man]

Interestingly, the dowel rod technique shows an oal of 2.845" to kiss the lands. Looks the the sharpie was lying......by almost .100"!

Sent from my SM-S820L using Tapatalk

[Texas10]

I found that major changes occurred to the lands with the first bullet down the tube on a new barrel. I measured as you are, before and after the initial few rounds and documented big differences in distance to lands. I also had a camera to look down into the throat and saw how the start of the rifling was knocked down after just one shot.

In my Criterion barrel the new, never shot lands were more than twice as high as they were wide, presenting an odd view when looking into the throat with my camera. They had a partial 45 degree chamfer, but after a couple of rounds fired, they began to look "normal".

So don't bother measuring lands with your new barrel. Load well short of the lands and break it in thoroughly before doing any measuring you are going to want to depend upon.

JMHO. YMMV

[71velle]

Can anyone post accuracy results due to bullet seating depth? I am new to handloading and have read many times the importance of the seating depth but have not seen any results.

[FW Conch]

^It is mostly a trial and error process, based on what a certain bullet likes in a particular barrel^. It is mostly agreed we should first find the Optimum Charge Weight that our barrel likes. Then fine tune with jump. accurate shooter.com and other sites have info on the subject. It is somewhat an advanced reloading concept used after the basics are mastered. :-)

[darkker]

+1
Jump is typically a fine tuning deal only, IME.

[LoneWolf]

Yep I only measure the lands in the beginning to make sure I won't be jammed causing pressure issues. I go shoot +/- 50rds, give it a very light cleaning and re-measure for load dev. I start at 15 thou off find my charge and most of the time if it looks like an adjustment is need I try 5 thou each way and one of them usually tightens up the load that last bit. After that I shoot it till it stops shooting, Clean it and if it doesn't keep shooting I test velocity and increase charge as needed. If you get the same velocity through charge and it still doesn't tighten up than measure and chase the lands. If it's not shot out this method will keep it going for you. I determine my barrels shot out when my rounds no longer fit in the mag due to OAL or the barrel just will not hold 1/2 MOA (Competitive requirement).

[bigedp51]

Can anyone post accuracy results due to bullet seating depth? I am new to handloading and have read many times the importance of the seating depth but have not seen any results.

Below a very good post by Erik Cortina of "Team Lapua USA" with over 95 pages of postings with questions and answers.

Long range load development at 100 yards.
Erik Cortina
Team Lapua-Brux Captain
http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

Some of you have asked for more detailed instructions on how I do this. Here they are:
1. Find Jam by seating a bullet long on a dummy piece of brass (no primer nor powder) and apply die wax to the bullet ogive and record it's base to ogive length.
2. Chamber the round and close the bolt.
3. Snap the bolt open and measure the base to ogive measurement. If it is shorter than previous measurement, this is your jam. Do it a few times with different cases to make sure.
4. Load a known powder/primer/bullet combination. I load 4 of each powder charge in 0.5 gr. increments and seat bullets at jam - .020". I use one shot of each to get barrel fouled up and also keep an eye for max pressure at the same time. You can also use these rounds to break in a barrel if you are inclined to. If I encounter pressure on the hotter rounds, I will not shoot groups with the other loaded rounds and will pull bullets when I get back home. Do not shoot in round robin style because position and natural point of aim will be compromised.
5. Shoot 3 shot groups starting from lowest to highest. All groups are shot over a chronograph.
6. Examine target and find the place where consecutive groups line up vertically and ES is the lowest and speed increases the least from one group to the next.
7. Load to the middle of the powder node and do a seating depth test.
8. Load 3 shot groups starting from Jam - 0.005" all the way out to Jam - .040" in .003" increments.
9. When you find the seating depth test that shoots the best, load towards the longest side of the node to allow more room for throat erosion.
10. Final step is to load the new seating depth and load 5 shot groups in 0.1 gr. increments 0.5 gr. on each side of node (if pressure limits are not reached). This will cover an entire grain of powder and you will be able to pinpoint where the powder node starts and ends. In the summer, load towards the low end of the node, and do the opposite in the winter.

[LongRange]

http://www.texasprc.club/preidloaddev/

[71velle]

You guys are awesome!!!! Great resources, exactly what I needed..

[big honkin jeep]

Ok, so I'm not a shooter for a major manufacturer, or a top competitor at rifle matches, but over the years I have found something that keeps everything very consistent and it doesn't get any simpler. I just use a neck sizing die and seat my bullets just a hair long. Then when I chamber a round the bullet pushes back in the case just a little and seats with the ogive just touching the lands. I seat the bullet to it's final position with the bolt. Hard to get more consistent than that and about as simple as it gets. I'm also convinced this method provides consistent bullet start pressure taking neck tension for the most part out of the equation. Since I'm usually working up from scratch I've never had any pressure problems that I've read about that can be associated with "Jammed "bullets.
Just thought I'd throw it out there.

[LoneWolf]

Ok, so I'm not a shooter for a major manufacturer, or a top competitor at rifle matches, but over the years I have found something that keeps everything very consistent and it doesn't get any simpler. I just use a neck sizing die and seat my bullets just a hair long. Then when I chamber a round the bullet pushes back in the case just a little and seats with the ogive just touching the lands. I seat the bullet to it's final position with the bolt. Hard to get more consistent than that and about as simple as it gets. I'm also convinced this method provides consistent bullet start pressure taking neck tension for the most part out of the equation. Since I'm usually working up from scratch I've never had any pressure problems that I've read about that can be associated with "Jammed "bullets.
Just thought I'd throw it out there.

And what if you have to eject the round? Sounds like you would end up with a mess of powder in your action and chamber... if you shoot on a range and in matches and a cease fire is called you are required to unload all ammo. That's when I see this becoming and issue. I have heard of this process with some FClass shooters and what not. Not the best for a field gun though in my opinion.

Again, I believe it works! Just not the best option for the field.


Sent from my iPhone using Tapatalk

[Mountain Man]

Ok, so I'm not a shooter for a major manufacturer, or a top competitor at rifle matches, but over the years I have found something that keeps everything very consistent and it doesn't get any simpler. I just use a neck sizing die and seat my bullets just a hair long. Then when I chamber a round the bullet pushes back in the case just a little and seats with the ogive just touching the lands. I seat the bullet to it's final position with the bolt. Hard to get more consistent than that and about as simple as it gets. I'm also convinced this method provides consistent bullet start pressure taking neck tension for the most part out of the equation. Since I'm usually working up from scratch I've never had any pressure problems that I've read about that can be associated with "Jammed "bullets.
Just thought I'd throw it out there.
How do your hot loads compare in weight to max book loads? I'm trying to understand the dreaded and feared pressure spike I keep hearing about from your practice. A lot of guys jam their loads, it seems to work for most of them very well!

This rifle will likely only be used by myself, deep in national forest land, with pre targeted mountain sides. The threat of having to remove a round without using a dowel rod isn't huge, if the jam juice is worth the squeeze.

Sent from my SM-S820L using Tapatalk

[LongRange]

most bullets shoot better with a jump...even VLDs...can you make most bullets shoot jammed? YES! do bench rest guys and F-class guys jam bullets? YES! are you a BR or F-class shooter? most likely not. what has the second biggest effect on POI? charge/powder weight...next would be seating depth...next would be case prep...next would be neck tension...next would be primers and so on...the hole is deep...some ppl may want to argue what effects POI more or less but ive spent a LOT of time and shot out a few barrels doing actual field testing chasing accuracy and "THE PERFECT LOAD".

ill tell you the single biggest effect on POI is the shooter...if he is not capable of shooting tiny little groups day in and day out then how will he know if he has found the perfect load or if what he is doing at the loading bench is actually working? i am no super marksman and do not claim to be an expert on loading or shooting but i can go out and shoot pretty small groups pretty consistently...ive NEVER shot a bench rest match(but i think i will next season)i shoot F-class matches both 600yd and 1000yd...i also shoot long range varmint silhouette,PRS and short range tactical matches and though i shoot the same loads at all they are all a different style of shooting and take a different mind set.

now back to jamming or not jamming...

this is IMR4451 with a 107g SMK i was playing with a couple of weeks ago...
107g SMK .025 off the lands CCI 200 primers
#1...40.5g
#2...41g
#3...41.5g
#4...42g

http://i1239.photobucket.com/albums/ff515/LTT-/IMG_0076.jpg (http://s1239.photobucket.com/user/LTT-/media/IMG_0076.jpg.html)

this is a 115g DTAC seating .020 off the lands CCI 200 42g H4350 5 rounds at 100yds

http://i1239.photobucket.com/albums/ff515/LTT-/Mobile%20Uploads/1475928621.jpg (http://s1239.photobucket.com/user/LTT-/media/Mobile%20Uploads/1475928621.jpg.html)

this is the same day same load but the 115g DTACs are seated .038 off the lands 5 rounds at 100yds...and just so you know i was having a good day...

http://i1239.photobucket.com/albums/ff515/LTT-/Mobile%20Uploads/1475928618.jpg (http://s1239.photobucket.com/user/LTT-/media/Mobile%20Uploads/1475928618.jpg.html)

heres some 140g berger hybrids at .035 off the lands...

http://i1239.photobucket.com/albums/ff515/LTT-/Mobile%20Uploads/1454853623.jpg (http://s1239.photobucket.com/user/LTT-/media/Mobile%20Uploads/1454853623.jpg.html)

this is 10 rounds with 10 different charge weights...142g SMKs all seated .025 off the lands at 100yds...

http://i1239.photobucket.com/albums/ff515/LTT-/Mobile%20Uploads/1467481978.jpg (http://s1239.photobucket.com/user/LTT-/media/Mobile%20Uploads/1467481978.jpg.html)

i could go on but ive cluttered up your post enough and the point is that bullets DO NOT have to be jammed to shoot small groups.

[FW Conch]

^ "MM" ^, jamming the lands is a reloading technique practiced by shooters that measure their targets and groups in thousands with calipers. With the type of shooting You describe, are You going to take Your calipers with You to the national forest and mountain side? I agree with Lonewolf. There is no need for accuracy to supersede practicality or safety, in a given shooting situation.

This reminds Me of the current craze with high BC, boat tail, long range bullets. How much money is wasted by shooters buying these pills that will never shoot over 300yds, rendering the extra expense useless. "The colorful shiny fishing lures are designed to catch 'fisherman'".

I reload and shoot from the bench to develop loads that give Me a high level of confidence. When I take that rifle and load to the field, I forget all about that OCD, and put em all in a small pie plate! ;-))

[rjtfroggy]

Like Long Range I have spent hours at the reloading bench and firing line to find as close to ideal load and seating depth, but unlike him I do shoot BR and just a little variation makes a big difference in your score. When shooting at a 1/16th dot inside a 1/2 inch circle at 100 yards every little thing matters we are talking 1/4 inch consistency at 100 yards.
Now on the other hand my hunting rifles are 1 inch shooters at 100 leaves plenty of room for errors in judging distance, plus they are all light weight guns not made like my BR guns.