Oooops....

ok. I just ran a computer simulation of a round being fired. it showed that the case neck expanded after the bullet contacted the lands, why because once the bullet made contact that is when the pressure build enough to expand the neck.

And what does this computer simulation do when you remove the barrel (or cut it right before the chamber)? Does it say that the bullet stays in the case because there is not enough pressure generated?
In my opinion what happens in that milisecond is very difficult to simulate, unless you take a lot variable things not into account. Do you 'crown' your brass? You know what happens when there are small impurities in the crown of the barrel...
I don't believe in science on that level.
What about the 6.5x54 MS, that's known for a lot of free flight and still it's a very accurate round. My 6.5x54 MS is a stutzen and just laughs with the theory of free floating barrels. The barrel is attached to the wood on 3 different places and still it's shooting very good.
In my opinion the old gunsmiths had no need for sophistated machinery to make a good shooter. On some point 'knowledge' changes in 'believe' and I stopped trying to explain believe...

No disrespect intended with the grashopper reference Long - When you have been here a while you will understand that.

Simply stated the bullet heel is unsupported as it releases from the case mouth for the few nano seconds before rifling is engaged.

Whose simulation did you run? was it a You Tube video?

This is a good debate.

Its my understanding that at the point of ignition from the primer to the powder, the powder in (nano seconds) does not ignite all at once and reverberates back and forth against the inside of the case as pressure builds up. Air space inside the shell (compressed or not) contributes to acceleration of burning the powder, as the pressure builds up, it pushes the bullet out in towards its target. As the bullet is traveling out the muzzle, pressure fluctuates at different points up till bullet leaves the muzzle. Now on firing any projectile, the gases which propel the bullet even after it leaves the shell are still high and thats why you have to resize the the shell or neck after firing since brass with 35k lbs on up will form to outside (chamber). This is a lot more pressure then required to seat the bullet and crimp it. Just have to remember the minute the bullet hits the rifling, you have friction which will keep pressures high till the bullet exits.

its all good, lets take a garden hose with no nozzle on it and turn the water on, the water still comes out but with no force, now put a nozzle on it and u get pressure that shoots the water a greater distance. if the neck expands to quickly (before the bullet contacts the lands)the pressure escapes past the bullet. but we r talking about "nano or micro seconds" no matter the bullet still travels down the barrel.

Dawgdad I believe the term Grasshopper was made popular by the martial arts/hollywood movies. we use the term quite alot as a reference to adress your student or person you are trying to explain something to. always with great respect for person adressed. eg they wouldnt be your Grasshopper/apprentice if you didnt like em.
a good descussion. I dont know how much my bullets jump cause Ive never seen the need to know. speaking of bullet movement in chamber have you guys (and girls cant forget Suz) seen the speel on the remington hypersonic loads? a chamber inside a chamber so to speak.

Dawgdad wrote:

robd wrote: This is an interesting topic. OK Rob - you are new here so I will warn you right up fron, This subject I am getting ready to address has been a powder keg in the past

Hmmm. Apparently no wiser words have been said.

Long wrote:

not ture? i did not say the case does not expand. expand or not the bullet does contact the lands before it leaves the case.. grasshopper? Ive been loading for 35 yrs and own 27 rifles that I load for. I am also a gun smith and do alot of chambering and recrowning.jump, leaveing point A and contacting point B without being at both places at the same time.

Gidday Longy...I think Dawgdad's post saying "Not true grasshopper..." is tongue in cheek mate. He is not questioning your knowledge.

From memory the phrase Not true grasshopper comes from the old TV show starring David Carradine in Kung Fu during the 70's.

Cheers, Vince

Enough of this "grasshopper" stuff. Let's get back to the argue...aah...discussion of the "bullet jump".

Cheers, Vince

like i said its all good. Im glad to have found u all to share with, when ever I try to talk to my wife her head spins round and round and she says as long as the damn thing goes off thats all I care about.

Long...Just make sure you have a beer [shine] in your hand and are standing close enough to the fire to keep warm and so we can hear ya good.

Long wrote:

like i said its all good. Im glad to have found u all to share with, when ever I try to talk to my wife her head spins round and round and she says as long as the damn thing goes off thats all I care about.

HaHa - sounds like my daughter. Since we hunt in the thick woods here in the northeast, she only cares about minute-of-deer at 100 yards or less. While she is impressed (a little) with 1/2 MOA and better from my rifles with reloads, her point is that her shotgun with any old slugs will still bring in the venison.

I do have a question that nags at me about freebore. After using the OCW method to work up loads with different bullets for my .300 WBY Mag, I was all excited about wringing out even more accuracy by fine-tuning using seating depth. All the tests and comparisons that I have shot so far show that group sizes with this particular rifle are the same - regardless of the amount of bullet jump. Standard length rounds have about .300" to .360" freebore (depending on bullet). I have tested 5-shot groups in .020" increments all the way up to just touching the lands. No difference.
Is it just this particular rifle? Do I have a lucky set of seating dies? Exceptional brass? ( I used Weatherby, Nosler, and bulk Remington brass for the tests). Is the throat in Weatherby rifles very close to bullet diameter?
I'm not complaining, just puzzled. This rifle is exceptionally accurate.

By the way - my .204 shoots miniscule groups that amaze me. It also has a very long jump with the loads it likes best. (Cant remember the measurement, but I was surprised how long it was.)

I guess that Lady Luck is with me when I pick out a rifle.

marty, con't fix what ain't broke ... and ... don't argue with success. I've read technical articles where it is not unusual to find rifles that shoot well with the bullet more than 0.100 off the lands (like your Ruger). For your .300, is that just one type of bullet or has seating depth not mattered for several different type of bullets?