OzFclass

Hello.

Gyro says much of this measurement problem goes away if the bullet is jammed. Is this EC jammed, where the bullet cannot be pushed any further forward or is it somewhere short of that, but firmly into the throat/rifling? Perhaps Alan could issue a directive that the absolute limit of jammed be called, say, "Stuffed", and anywhere short of that is called "Firmly in". There could be sub-categories, such as, "Just in..", "More than just in..", "Well in..", "Firmly in.." "The full 6lbs in..", which may be the same as "Stuffed". It would have more meaning than, "I jam 20 thou."

As I don't jam, I don't care about any of that. Maybe I should.

I "book" my barrels in for what I call a "Major Clean" every 200 or so rounds. After the MC, I check on my Throat Depth. It may be sweet to know the very last point where what is left of the throat touches the bullet, but that's it, "sweet". It has no other relevance, because the throat is a jumble of broken teeth. Where the bullet first ENGAGES the throat/rifling may not be definable. But for the theories of how much "In" or "Off", this point of ENGAGEMENT is "Touch" or "Zero" or however you may term it.

Walt's concept of applying forward pressure to the bullet, when using the Stoneypoint to find the bullet's "location", makes sense to me. "Finger pressure" is like the bus driver's foot. Use your trigger gauge. I do not know how to establish "ENGAGEMENT" accurately. As with almost everything we do, Trial and error.

When the bullet stops, ever so slightly, falling out as you withdraw the Stonypoint case, just might be very close to ENGAGEMENT, TOUCH, ZERO. Work from there off; or if you must, in. That could be as little as 2lbs pressure, but not in my experience.

After reading Rod,( who seems to be saying he is a jumper???), there is a need to re-establish the Symbiotic Point for "off" the lands, just as there is for "in" the lands. I never thought of that. Off the lands, you're safe. No need to change; same seat, same Load Density, don't be concerned about increasing jump.

Oh dear.

John T.
22.7.20

RDavies wrote:

wsftr wrote:

pjifl wrote:.

I don't understand - isn't this what we call load development and we shoot to look at it on paper. I dunno about all the pristine comments by others as well - someone like Tony Boyer would say - no point in checking ya load in a honey hole...

There are different levels of pristine conditions and in some conditions you are chasing your tail testing in and it is not always what most people expect. But that is a subject for another day and in my view, much more important than worrying about minor differences in seating depth or powder charge.

Thanks for the reply - yes agreed - I think we all know this but for whatever reason whenever we there is some discussion about load development the word pristine comes into play - heck pristine at 100 yards might not be pristine at 300 yards - whatever ya poison is for load dev.
The principle of what Tony was stating struck a cord with me and caused me to reassess when I would go out and test and what I was looking for on paper.
IME seating depth can make or break a load - maybe thats not others experience - no argument.
Put it all together and it seems like a black art - the very best seem to be able to make a science of it though

there is no doubt that the 2 main tuning aids are powder charges and ogive relationship with the lands.
you have to test one of these , and then the other, independantly.
say you went for seating depth first, then you have to try different powder charges at that seating depth. once you find the best charge, it never hurts to retry seating depth at the best charge.
we tend to think in terms of seating depth when what we really mean is relation of the bullet to the lands.
seating depth is just a way to measure this.
with regards measuring "touching the lands" with the hornady tool, i can get measurements of +/- 0.0005" with the same bullet in 20 tries in a row.
letting the bullet push a cleaning rod as the bullet moves forward can help this process.
on another note, i remember bench shooters looking for a square rifling mark on the bullet as a starting point.
and this is the key.
as a starting point is where you start measuring.
if you find a full jam where a bullet seats into the rifling with tight neck tension, that is where the most pressure is.
a max safe load at that seating depth will reduce pressure as you seat deeper, going from less jam to jump.
bruce.

Truth is we’re all playing around with the same details in various ways. The real beauty of EC’s method is it gives a solid simple starting point. The fact that RD supports it in principle sure doesn’t hurt either ! I’m certainly taking note.

Gyro wrote:Truth is we’re all playing around with the same details in various ways. The real beauty of EC’s method is it gives a solid simple starting point. The fact that RD supports it in principle sure doesn’t hurt either ! I’m certainly taking note.

At the end of the day it's all about finding a starting point. I don't think it matters what that starting point is so long as it can be duplicated. Unlike some of the "experts" on this forum I do use the Hornady/Stony Creek tool, with which I have developed a method of using it that works for ME in finding that constant starting point. As someone said there are more than one way to "skin a cat". I have watched the Youtube videos and while I am sure all of them work none of them are for ME, I am a follower of the "kiss" method, It seems to me that many of us go out of our way to complicate many things. It should be remembered that this conversation is about one thing, determining a seating depth starting point of a bullet. I think that one thing that Mr Cortina has highlighted is one of terminology and I agree with him about "jam" and "into the lands". I think that "jam" for most of us is "into the lands" I know that applies to me as I can unload my "jammed" ammo at any time with no problem and I think that applies to most of us who shoot "jammed".
Keith H.

I feel I am in the same position as you Keith regarding ‘Jam’

I can certainly unload a round that has been ‘jammed’ 0.015 or 0.020” into the lands. It’s far from being jammed hard into the rifling. That’s why I like the Wheeler method of finding that first gentle contact point, then going in from there.

As for the Stoney creek style tools. That’s great it works for you. I do not profess to be an ‘expert’. Perhaps that’s why I can’t get it to work repeatably. But the way I have ben doing it in my relatively short, non expert capacity still works quite well for me..........

ben_g wrote:I feel I am in the same position as you Keith regarding ‘Jam’

I can certainly unload a round that has been ‘jammed’ 0.015 or 0.020” into the lands. It’s far from being jammed hard into the rifling. That’s why I like the Wheeler method of finding that first gentle contact point, then going in from there.

As for the Stoney creek style tools. That’s great it works for you. I do not profess to be an ‘expert’. Perhaps that’s why I can’t get it to work repeatably. But the way I have ben doing it in my relatively short, non expert capacity still works quite well for me..........

So from the "Wheeler 1st gentle contact point" how far do u normally go in Ben before risking leaving the boolit stuck on ejecting a loaded round ? I personally believe a jammed boolit setup is fine, with some rules.

And BTW I wouldn't go anywhere near a stuck boolit scenario if I thought that could happen because it's a farking disaster, all over see u later ...

The furthest I typically go in is 0.020” with VLD’s

Having said that I have only one 284barrel that is shooting VLD’s into the lands.

All my other barrels are running either Sierra or Berger hybrids with some amount of jump.
I have two 300WSM barrels that shoot 215 hybrids into bugholes with jumps anywhere from 0.010 out to 0.030 so I just set them up for the 0.010” jump and only touch them if accuracy falls away.
The first barrel has done 800rounds (After the first 150 or so) without having to touch the seater die. (Haven’t even bothered to retest where the lands are.)

The second barrel has just hit 150rounds so will probably redo the measurement and adjust to it then leave it alone unless it needs touching. The 215 just doesn’t seem at all fussy.

As for Sierra 183 7mm bullets, I have found that’s a bit of a different story.

I think I’m relatively lazy in my load development compared to some. I test everything in club shoots. I don’t have ready access to a short 100 or 200yards range to shoot endless groups.

https://precisionrifleblog.com/2020/04/ ... ment-tips/

If you read between the lines of this article the further your jumping the less critical changes to jump are.
It is a PRS article and I’m not sure they are after the same accuracy we are. But they shot a lot of bullets and collated a lot of data.

This has been a very good thread, and I think many will have benefited from the knowledge and experience of the posters. I know I have. Despite my past experience near the sharp end of F-Open, I've never really nailed the art of tuning, probably due to being based at a range that rarely gives you ideal (pristine?) conditions for testing. This weekend I intend to try some jumped loads for the first time in a while . Maybe it'll inspire some others to experiment as well.

ben_g wrote:The furthest I typically go in is 0.020” with VLD’s

Having said that I have only one 284barrel that is shooting VLD’s into the lands.

All my other barrels are running either Sierra or Berger hybrids with some amount of jump.
I have two 300WSM barrels that shoot 215 hybrids into bugholes with jumps anywhere from 0.010 out to 0.030 so I just set them up for the 0.010” jump and only touch them if accuracy falls away.
The first barrel has done 800rounds (After the first 150 or so) without having to touch the seater die. (Haven’t even bothered to retest where the lands are.)

The second barrel has just hit 150rounds so will probably redo the measurement and adjust to it then leave it alone unless it needs touching. The 215 just doesn’t seem at all fussy.

As for Sierra 183 7mm bullets, I have found that’s a bit of a different story.

I think I’m relatively lazy in my load development compared to some. I test everything in club shoots. I don’t have ready access to a short 100 or 200yards range to shoot endless groups.

but is your 0.020 the same as my 0.010?
bruce.

bruce moulds wrote:

ben_g wrote:The furthest I typically go in is 0.020” with VLD’s

Having said that I have only one 284barrel that is shooting VLD’s into the lands.

All my other barrels are running either Sierra or Berger hybrids with some amount of jump.
I have two 300WSM barrels that shoot 215 hybrids into bugholes with jumps anywhere from 0.010 out to 0.030 so I just set them up for the 0.010” jump and only touch them if accuracy falls away.
The first barrel has done 800rounds (After the first 150 or so) without having to touch the seater die. (Haven’t even bothered to retest where the lands are.)

The second barrel has just hit 150rounds so will probably redo the measurement and adjust to it then leave it alone unless it needs touching. The 215 just doesn’t seem at all fussy.

As for Sierra 183 7mm bullets, I have found that’s a bit of a different story.

I think I’m relatively lazy in my load development compared to some. I test everything in club shoots. I don’t have ready access to a short 100 or 200yards range to shoot endless groups.

but is your 0.020 the same as my 0.010?
bruce.

No it’s probably not. That’s the whole point of EC’s video. He did take the roundabout way of getting there.

But Gyro asked me where I seat based on my preferred method of finding light contact with the lands. I addressed in another post above that the measurements I use are useless to anyone else unless they employ the same technique to measure.

I agree with EC that accurately measuring lands position, particularly on a worn barrel in varying degree of cleanliness is a relatively inaccurate science. I can reproduce a repeatable measurement with the same bullet, but as EC talks about in his video, what exactly is that measuring as far as lands shape goes.
All I know is for my barrels that I jammed with VLD’s going in a further 0.015 to 0.020” from my ‘contact’ point works most of the time.

i was just making the point that we might all establish a starting point the same but think it is different.
nothing wrong with this, as long as it is repeatable.
from there we test until we get the best groups.
myself will feel uncomfortable at 0.020 in by my definition, but prefer a max of 0.010 to 0.015, and then with good neck tension and proven extraction ability.
you don't need much fouling in a throat to turn 0.010 into a bigger jam, due to the angle of the lead.
bruce.

After using a projectile to determine contact, take a good look at it. Usually there will be a small dented ring mark. This tends to produce better repeatability if it is subsequently reused many times. But any absolute measurements have been destroyed. It is not a standard projectile any more. The contact being at an acute angle amplifies this error. So you really need to repeat this with a fresh projectile every time. Which assumes they are all the same.

That is not to say the exercise was useless - but it does need judicious use.

Peter Smith.

bruce moulds wrote:

ben_g wrote:The furthest I typically go in is 0.020” with VLD’s

Having said that I have only one 284barrel that is shooting VLD’s into the lands.

All my other barrels are running either Sierra or Berger hybrids with some amount of jump.
I have two 300WSM barrels that shoot 215 hybrids into bugholes with jumps anywhere from 0.010 out to 0.030 so I just set them up for the 0.010” jump and only touch them if accuracy falls away.
The first barrel has done 800rounds (After the first 150 or so) without having to touch the seater die. (Haven’t even bothered to retest where the lands are.)

The second barrel has just hit 150rounds so will probably redo the measurement and adjust to it then leave it alone unless it needs touching. The 215 just doesn’t seem at all fussy.

As for Sierra 183 7mm bullets, I have found that’s a bit of a different story.

I think I’m relatively lazy in my load development compared to some. I test everything in club shoots. I don’t have ready access to a short 100 or 200yards range to shoot endless groups.

but is your 0.020 the same as my 0.010?
bruce.

Bruce, the short answer is NO, but it does not matter, so long as YOURS and MY measurements are repeatable for US. Mine does not have to be the same as yours, my barrel/chamber will be different anyway, all of these measurements will and can only be "personal" and that is fine provided you and I can repeat them, that is the key!!
Keith H.