jam or jump?

[kohai133]

I have always ran tangent ogive bullets in the with jump, sometimes a LOT of jump to make mag length. Just received a new batch of vld bullets (Hornady 22 cal. 80gr. AMAX). I have read/heard tell that vld's should be jammed. Since these will be single loaded that will be fine. This is my first time experimenting with jammed bullets, and vld's for that matter. Can someone let me know if jamming vld's is the correct way to go and how much should I drop my initial powder charges by?

TIA,
Jim

 

[kohai133]

Your response made me go back and take another look at 'em. I thought they were vld's because the AMAX's appear to have a very conical nose shape compared to the Sierras that they were laying next to on the bench earlier. Now that I look at the AMAX's by themselves it looks like they have two step radius on the nose. Donovan, thanks for making me relook at them.

Cheers,
Jim

 

[Luke_NL]

Haven't heard any rule as black and white as that. Actually I kind of wish things were that easy. (if this is a hard and fast rule I missed, please school me!)

First of, I am assuming you have established the seating depth where the bullet is touching the lands. I jot that down as "OTL". Then using a lower end (! especially important when jamming) load the rifle likes for bullets in the same weight class (preferably of similar dimensions) make a few batches: OTL (0), OTL+0.005, OTL - 0.005, and so forth. Shouldn't require any math to figure out what the rifle likes. From there on in, hone in on seating depth, then powder charge again to work up the load to within a node. Once in the node, I'll toy around with the seating depth again but only by small margins. Admittedly, it takes me quite a few shots to be truly settled on a round I'm certain about, but I have fun working the gun and press. Some people take up knitting.

Side-note, I have found Berger VLD's pretty forgiving in terms of seating depth. I'll be trying out A-max soon but they look very different from my Bergers.

 

[watercam]

Just try a variety of seating depths. You can not obtain the optimum seating depth asking on the internet! Using five shot groups jam them .010". Seat them just touching. Jump them .010", .020", .030", .050" and .080".Somewhere in there will be something better than the rest. Every barrel in different, one has to try a variety with each to find what will work for his or her particular rifle/barrel. There is no short cut, you owe it to yourself to find out what your rifle/barrel likes.
I have had VLDs shoot better jumped .020". I have had conventional ogive bullets enjoy being jammed. It is called working up a load. You will be doing it every time your rebarrel. Get used to it.

 

[7x57 Shooter]

I always mark a dummy bullet with black marker, I try it in the rifle and seat it until it does not show any rifling marks. I repeat this with every different style of bullet and always have excellent results. I don't like the idea of 'jamming" the bullet as it usually raises pressure and can cause erratic results on paper.
As an example, Barnes bullets are supposed to be loaded 50 to 70 thou off the lands to make sure of no pressure spike.
Loading them to where they "jam" would be high in pressure due to the solid copper design, play safe. :}

 

[Wildboar]

I would refer you to an informative thread that should answer your question. The answer is it depends, but shows you how to find out. [http://forum.accurateshooter.com/index.php?topic=3814361.msg36221455#msg36221455]

 

[vtmarmot]

Get the Berger Manual and read the section on seating depth for VLD's or call them and discuss it. They actually suggest that you try various and surprising amounts of jump with them. They ARE sensitive to seating depth, but it may be some jump that works best.

 

[amamnn]

Not too long ago I read something about VLD type bullets and trouble with inconsistent seating due to the extent of ogive beyond the datum point and the nature of seating stems in most all seater dies. I was given a bunch of VLD bullets and had been fooling with them without a great deal of success. The above seemed likely to be a major reason, if not the reason for the seating variance I was getting.

Redding then introduced, as I recall in cooperation with Berger, a vld micrometer seating stem/top to replace the standard seater stem. I bought the replacements for the seaters I use for the two cartridges I load with VLD bullets. Problem solved.

I don't know if this is all in the Berger book, but there was something about it on their website back when I was looking into the VLD thing. Redding also had something on theirs.

 

[amlevin]

"Jam or Jump" is a question answered best by the rifle. I have one that "patterns like a shotgun" when jamming bullets but jumping them almost .200" gives me cloverleafs at 300 yards.

Yes folks it's a Remington with a factory chamber.

 

[boltgunluvr]

DO NOT start out with touching or jammed. Better to start .020-.030 jump and check for pressure.

 

[boltgunluvr]

"Jam or Jump" is a question answered best by the rifle. I have one that "patterns like a shotgun" when jamming bullets but jumping them almost .200" gives me cloverleafs at 300 yards.

Yes folks it's a Remington with a factory chamber.

....Diddo.........all my Rem700s love jumping.

 

[amlevin]

DO NOT start out with touching or jammed. Better to start .020-.030 jump and check for pressure.

OR

Start out with it jammed and use the starting load for that bullet/powder, stopping when you reach pressure signs. Then adjust for jump.

 

[lpreddick]

i WAS once only a jumper. i could load groups of three with the same charge and seat them just off the lands and move back by .005, .010, .015 etc and almost always find a "node". sometimes the hole was in the zeros...i was very proud. chris long's "shock wave theory" explained what was hapening and i was hooked. then something happened. find the accurate seating depth, load a bunch and wait. after a few months i would take my beauties to the range and WTF! holes everywhere! sometimes i would seat them .005 more and they would shoot better...sometimes not. change in neck tension was my guess (this brings up "cold welding"). what do the benchresters do? they invariably seat into the lands...a square mark or 1/2 as long as wide. vary the load and i find a load that shoots small. how long will it be there? months to a year. read an article in precision shooting from 1983 by a very succcesful br shooter who noted this very same thing...jump loads would not shoot after sitting for awhile whereas into lands would...he could not explain what he was seeing and most br shooter were also into the lands. .010 to .020 into assures you will be contacting all lands as they can wear unevenly and they round off at the edges. if neck tension is inadequate and you seat too far, the bullet goes into the neck...like everything in this endevor , try everything and decide for yourself.