• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Jumping bullets ??

I was taught to always touch the lands, and have only ever jumped when I had to use magazine length for an AR rifle and then always thought that doing so is part of the reason they seem to be less accurate that a bolt rifle loaded to touch. I watched the video that is posted about 2 bullets hitting each other in flight and at 17 minutes in the video he show a cut away chamber and a high speed shot that I think proves bullet jump is not the best for accuracy. Look at it and tell me what you think.
 
I don't know about "best" for accuracy, but I was taught the contrary, never seat bullets into the lands and to avoid any possibility of this, use a seating depth that account for variations in bullet ogives.

My first criteria in reloading are to produce a safe and reliable load. The last thing I want is a bullet stuck in the lands when I am in the field or worst a pressure surge.

I never have had any trouble finding an accurate load that meets my standards for a precision varmint / predator hunting load by seating well off the lands. However, I am not a benchrest or long-range shooter nor do I wish to be.

I have owned several Remington 700's over the past 50+ years and most of them had a lot of free bore, yet I was able to develop sub moa and in some cases 1/2 moa loads seated well of the lands.
 
I was taught to always touch the lands, and have only ever jumped when I had to use magazine length for an AR rifle and then always thought that doing so is part of the reason they seem to be less accurate that a bolt rifle loaded to touch. I watched the video that is posted about 2 bullets hitting each other in flight and at 17 minutes in the video he show a cut away chamber and a high speed shot that I think proves bullet jump is not the best for accuracy. Look at it and tell me what you think.
I've always suspected that the blow-by happening before the bullet reaches the land and fully engraved has some kind of variable effect on the consistency on target. I assumed that's why so many BR shooters do it and to some extent why so many match grade 22LR barrels are made to have the bullet pushed into the rifling for more consistency. In terms of accuracy vs precision, it's much more about precision than accuracy.

I have doubts that jamming the lands works well with barrels that have long free-bores, which means most factory barrels are probably not something to use this way. Though larger bullets with long BTO's might work in some instances.

Since I've always jumped my bullets, I've accumulated a lot of data. So I'm going to see what kind of results I can get by doing some jamming and see how it all might compare. :cool:
 
I start at -.005 off the lands during load development, and work back from there. I have 2 zF class rifles in .223 + .308. The .223 shoots a VLD style bullet very well at -.005, but groups open way up with more jump.
The .308 shoots non VLD bullets very well at -.025, groups open up if less jump is used.
Both rifles use custom barrels.

The difference is in the bullet ogive.
I've always found the the VLD bullets (secant)need to be close, while the non VLD (tangent) like a jump.

Nothing wrong with a jump if it's what YOUR rifle likes.
 
When it comes to the ultimate in extreme accuracy, such as achieved in Short Range Benchrest, there is no “set rule” concerning what seating depth will result in the optimum accuracy. Accuracy, as it pertains to the discussion, is defined as the agging capability of the rifle.

yearsago, when Bart first came out with his double radius FB that he named The Ultra, many of us found that jamming the bullets so that the marks were twice as long as they were wide produced outstanding agging capability. When Bruno came out with his first generation OO Boatsil, e found the same thing.

However with typical 7 1/2 straight shank Flat Base bullets such as the Fowler, Watson, Cheeks, etc, this simply did not work. Yhey tended to shoot best just touching, or perhaps just off the lands.

In short, every bullet/barrel combo has an ideal seating dept that you simply have to find, through trial and error, at the range.
 
Asking about this to any "F"-Class shooters , and you'll get answers from hard jam to .005 , to where-ever . It's a matter of the Barrel , Chambering , Type of Bullet , and even the powder and velocity you may shoot . There really is no set "Rule" for this , and it is something that is dealt with during load development . And changing Barrels will create this issue all over again .
I've been lucky that I have used the same Barrel manufacturer , the same Bullet , Primer and Powder for the last three years , and since the reamer is a 2013 FTR from Manson , I've only had to make very slight adjustments in the load and bullet seating when changing Barrels .
 
I have been a sling shooter for quite a while. In Nancy Thomkins book on Long Range Shooting, Mid discusses oal. He was loading for 4 people and rifles shooting 1000 yards. He would load all ammo long, with light neck tension to let the rifle finish seating the bullet. He and the girls won a truck load of trophies with that ammo. My 6XC barrels wear out quick enough as is without chasing and testing for some magical jump. I do what Mid does. Seems to be working on my ftr rifle so far. YMMV
 
I have been a sling shooter for quite a while. In Nancy Thomkins book on Long Range Shooting, Mid discusses oal. He was loading for 4 people and rifles shooting 1000 yards. He would load all ammo long, with light neck tension to let the rifle finish seating the bullet. He and the girls won a truck load of trophies with that ammo. My 6XC barrels wear out quick enough as is without chasing and testing for some magical jump. I do what Mid does. Seems to be working on my ftr rifle so far. YMMV
Can you extract a loaded round without the bullet sticking?
 
Sometimes, sometimes not. If there is a need to extract a loaded round I elevate the muzzle to prevent powder from spilling out. I carry a 3/16 brass rod 8 inches long to knock the bullet out if needed. I dont remember when I had to use it last, plenty of other shooters have needed it.
 
Great advice Mr Krafft. First rule then is do not let some one else grab your rifle to "help." If you do you will end up with an action full of powder. You keep your rifle upright and control the cartridge, let the helper drop the brass rod to dislodge the bullet. That rod lives in my cleaning box, priceless when needed. No spilled powder.
 
Sometimes, sometimes not. If there is a need to extract a loaded round I elevate the muzzle to prevent powder from spilling out. I carry a 3/16 brass rod 8 inches long to knock the bullet out if needed. I dont remember when I had to use it last, plenty of other shooters have needed it.
Years ago at my range an Experienced Competitive Benchrest shooter had just such a rod, but forgot to remove it after extracting the bullet. He lost an eye with the next round fired. So maybe better to bring a long cleaning type rod . A moment of inattention can cause a catastrophic event.
 
I have seen a factory HS Precision chambered in .308 with a ".050 jump to the lands", print a 5 shot group every time that could be covered with a dime!! Depends on the rifle and ammo.
All my ammo is loaded .010 INTO the lands. (except my gas guns)
I know ahead of time what to expect if I unload a live unfired round. :oops:
What works for one person doesn't mean it will work for you. ;)
 
Precision Rifle. Blog had a great article about this. They found that a.060 jump produced the lowest vertical spread at 800 yards. Very good write up.

I shot a 781-30x at the XTC state Championship last month jumping the bullets .2” at 200 and 300 and .080 at 600. My 22 Creedmoor didn’t mind at all.
 
Years ago at my range an Experienced Competitive Benchrest shooter had just such a rod, but forgot to remove it after extracting the bullet. He lost an eye with the next round fired. So maybe better to bring a long cleaning type rod . A moment of inattention can cause a catastrophic event.
Multiple incidents of cleaning rods being shot out. Pay attention to what your doing not giving a running narrative to the audience would be my advice, for all of us. What gets me about the jump crowd is they seem unwilling to try anything else for the most part. I am referring to bolt gun shooters, AR is a different animal from what my experience is in..
 

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Forum statistics

Threads
166,984
Messages
2,226,235
Members
80,084
Latest member
H3NN13
Back
Top