Determining touch vs jam

Just Touching

In his book, Mr. Boyer provides his definition of touching----pages 133 & 134.

He describes seeing faint land marks on opposing sides of the bullet and explains why on opposing sides.

It would seem to me that your "touch" should be far enough into the lands to prevent normal bullet dimension tolerances from making intermittent contact.

All in or all out of the lands.

A. Weldy
 
Most of my loading

Pete, this exercise was that I was trying to work up something with the Berger .30 115 gr FB bullet. When I was setting up the Sinclair Seating depth tool, I measured the length of fifteen bullets and had an extreme spread of .006 nose to base. While this was of no consequence when using the tool to find touch, I didn't want to measure off the nose for anything else. I intended to measure off the ogive using the Davidson tool. Your comments are very helpful and I intend to digest them further after I have digested my leftover dinner.

is for 30 Cal Benchrest rifles. I have shot em for around 20 years I guess. I have found that precise OAL's, measured as close to where the bullet will engage the lands, will deliver the most consistent accuracy. One can easily see .001" deviations and .003" will make groups pretty ugly, from my experience. I had one of those Sinclair tools and never found it to be consistent. I shed it as fast as I could. The method I outlined is very simple and consistent. On another note: I have found that, for seating consistency, one can not get the inside of their necks shiny enough. The trick is to keep em that way.;)

Pete
 
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Well that sound interesting,Jerry. Where can I find out more info on this tool? The term "dial micrometer" is intriguing.

I think I bought mine from Chuck at Holton. It comes with a couple of adapters. One for shoulder bump and a plastic thingy to adapt any 7/8-14 die to the micrometer top.

I made another adapter with my common used chamber reamer. Using this tool and zeroing the dial on the shoulder of a sized case, then seat a bullet so the dial measures more than the shoulder zero, reseat that bullet deeper than that difference, and bingo, you are at just touching.

If you wish, seat another bullet, say, 0.005" longer than the step above to verify your process.

Edit...he has a web site at 6mmppc.com
 
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As a practical matter, all that is needed is a starting point that you can reproduce reliably. Once you have that, you can change your seating depth to optimize your results, and return to that setting when you need to compensate for throat wear.

Boyd, your first sentence is the crucial part. You can reproduce jam more reliably and accurately than touch. Also, it's much easier to find touch by going from jam as you're just seating the bullet deeper each iteration of the search. Finding touch from the other side would be much more cumbersome by seating bullets. Which is why, I guess, people have been inventing tools to do it. So, my plan now is to do one the way you, Lee and other have recommended. I like the idea of smoking the bullet but I can't see cranking up my carbide lamp. Someone mentioned using a Zippo lighter. I gave up smoking 30 years ago but I think I may have a zippo lighter with a squadron logo on it in my Vietnam memento box. Now I gotta find that.

I'm beginning to feel that I'm drawing a tighter circle around this issue and I may have a good handle on it after a couple of days undistracted work.
 
Thanks for that info Toby. That's the first figure I've got from anyone that I can use for comparison.

I've also measured the difference between jam and touch for barrels where I had a gauge made from a barrel stub with the chambering reamer run about halfway up the shoulder. For bullets with a 7-ish ogive, and with bushings ~0.003 smaller than the loaded round, I generally get jam-to-touch differences of about 0.020 -- same as I found with Sinclair tool. Agreed that the Sinclair tool can't deliver super precision, but when moving away from the jam (which is how I test seating depth) I like to know when to stop, since I've never had much luck jumping bullets. If I don't have a chambered barrel stub gauge, I use the Sinclair tool instead.
 
I like the idea of smoking the bullet but I can't see cranking up my carbide lamp. Someone mentioned using a Zippo lighter. I gave up smoking 30 years ago but I think I may have a zippo lighter with a squadron logo on it in my Vietnam memento box. Now I gotta find that.

 
is for 30 Cal Benchrest rifles. I have shot em for around 20 years I guess. I have found that precise OAL's, measured as close to where the bullet will engage the lands, will deliver the most consistent accuracy. One can easily see .001" deviations and .003" will make groups pretty ugly, from my experience. I had one of those Sinclair tools and never found it to be consistent. I shed it as fast as I could. The method I outlined is very simple and consistent. On another note: I have found that, for seating consistency, one can not get the inside of their necks shiny enough. The trick is to keep em that way.;)

Pete

Pete, I shot Palma for a number of years before going into benchrest and I was never aware of this process for seating bullets. I've been considering turning my Palma rifle into an F-Class rifle. Unfortunately when I quit shooting Palma I had about 600 rounds of loaded ammo left. Not sure how to handle that. I've still got fired brass and could run a case and see how it compares to the loaded ammo. I was a barely OK Palma shooter and this just might have contributed to that.

Agree with you on the tools. I've got both the Sinclair tool and the Stoney Point and I've never felt I could get good repeatable results.

How do you use to polish the inside of you necks? I brush mine but that's probably not good enough.
 
I think I bought mine from Chuck at Holton. It comes with a couple of adapters. One for shoulder bump and a plastic thingy to adapt any 7/8-14 die to the micrometer top.

I made another adapter with my common used chamber reamer. Using this tool and zeroing the dial on the shoulder of a sized case, then seat a bullet so the dial measures more than the shoulder zero, reseat that bullet deeper than that difference, and bingo, you are at just touching.

If you wish, seat another bullet, say, 0.005" longer than the step above to verify your process.

Edit...he has a web site at 6mmppc.com

Well, turns out I got one of those thingys. But I've just been using it to measure shoulder bump. I've been using a Wilson 30 BR case gauge to use with the tool to check shoulder bump. Not sure that will do what you're doing with your adapter. I'll take a look at it and see.
 
Well to follow up on this thread and add a new wrinkle: Do you guys find the most-accurate seating depth to be with the bullet just kissing the lands, or jammed in hard? Or off the lands by a certain amount?
 
Neither....I like some marks but not heavy ones. When I start testing a single radius ogive bullet in the 7-8 range, I start with marks that are about half as long as wide, find my charge by test groups, and then fine tune seating depth from there. For bullets of the double radius ogive design that are closer to parallel to the throat angle, I get long marks right away, so I look at how distinct, or deep they are, usually using light but visible long marks as a starting point. Some of this will vary with the powder that is being used. I have done most of my 6PPC work with 133, but I have experimented with other powders and noted the differences in what they "like".
 
I've got a ton of those in different colors. I thought of them, but I also thought that smoke on the brass might displace easier than dried ink when you get close to the touch point. Don't know, just a thought

If you can find them the easy wipe/erasable markers work better than the permanent ones. Try one of each then take steel wool and see which one comes off. Just the steel wool is all you need, IMO.
 
Well, turns out I got one of those thingys. But I've just been using it to measure shoulder bump. I've been using a Wilson 30 BR case gauge to use with the tool to check shoulder bump. Not sure that will do what you're doing with your adapter. I'll take a look at it and see.

The adapter I made with my chambering reamer has the freebore and leade cone where the adapter that comes with the McClure tool doesn't. When the bullet sticks out the ogive rests against the leade cone just like it would in the chamber with the bolt closed. Your Wilson gage doesn't have the freebore/leade does it?
 
If you can find them the easy wipe/erasable markers work better than the permanent ones. Try one of each then take steel wool and see which one comes off. Just the steel wool is all you need, IMO.

Those are the ones used for white boards. I might have some in some old office junk. If not they're readily available in office supply stores. Good idea Jerry. :D
 
The adapter I made with my chambering reamer has the freebore and leade cone where the adapter that comes with the McClure tool doesn't. When the bullet sticks out the ogive rests against the leade cone just like it would in the chamber with the bolt closed. Your Wilson gage doesn't have the freebore/leade does it?

Nope, darn it.
 
Experiences and questions

I set out to find a way to determine touch and jam but have a question about jam----using a 221 FB and Sierra 52 gr match bullets.

If this interferes with Jerry's thread I'll delete it.

I found a setting very close to touch----very short marks for all four lands. Seating the bullet .005" shorter produces no visible land contact.
Haven't tried to refine this touch any closer and will continue to use this setting as a reference.

The effort to find the jam point has not been completed. Seems to me that if the round comes out of the chamber at the same length as it came out of the seater die, it is short of jam.

I increased the length in steps of .010" and compared the length of the round coming out of the seater to the length coming out of the chamber. I've increased length by .050" and chambering the round has not set the bullet further back into the case. IMO, jam has not been reached----have not tried seating any more than the .050" increase.

The questions----is there any practical benefit of setting out beyond this additional .050" ? I have this range of seating depth, all into the lands.
Are seating depths out close to or at jam useable ?

Would appreciate any answers.

A. Weldy
 
I set out to find a way to determine touch and jam but have a question about jam----using a 221 FB and Sierra 52 gr match bullets.

If this interferes with Jerry's thread I'll delete it.

I found a setting very close to touch----very short marks for all four lands. Seating the bullet .005" shorter produces no visible land contact.
Haven't tried to refine this touch any closer and will continue to use this setting as a reference.

The effort to find the jam point has not been completed. Seems to me that if the round comes out of the chamber at the same length as it came out of the seater die, it is short of jam.

I increased the length in steps of .010" and compared the length of the round coming out of the seater to the length coming out of the chamber. I've increased length by .050" and chambering the round has not set the bullet further back into the case. IMO, jam has not been reached----have not tried seating any more than the .050" increase.

The questions----is there any practical benefit of setting out beyond this additional .050" ? I have this range of seating depth, all into the lands.
Are seating depths out close to or at jam useable ?

Would appreciate any answers.

A. Weldy
It will not change to a longer length unless you increase neck tension
 
Loaded rounds

Pete, I shot Palma for a number of years before going into benchrest and I was never aware of this process for seating bullets. I've been considering turning my Palma rifle into an F-Class rifle. Unfortunately when I quit shooting Palma I had about 600 rounds of loaded ammo left. Not sure how to handle that. I've still got fired brass and could run a case and see how it compares to the loaded ammo. I was a barely OK Palma shooter and this just might have contributed to that.

Agree with you on the tools. I've got both the Sinclair tool and the Stoney Point and I've never felt I could get good repeatable results.

How do you use to polish the inside of you necks? I brush mine but that's probably not good enough.

I evolved into using a turret press for loading. I have all the dies I use for the cartridge I am loading in the turret, among them is a cam lock bullet puller that stays there. If your bullets are seated too long, it's easy, just seat them deeper. If they are seated too deep, simply pull them a bit and re-seat. I use Forster Micrometer seating dies, which give very accurate results. If one want .001" more or less, simply turn the top and you get what you ask for. I got away from the hand dies a decade+ ago and pre-load at home; have done it since the second year I have been competing. I shoot only a 30 BR now a day; not very well and not very often. I have roughly 1000 finished cases in boxes of 100, which I rotate as I use them and try to have them annealed after the 6th firing. Annealing the neck and shoulder junction will turn any case into a relatively new one. Your full length die will do all the rest for you after annealing. I use to shoot two rifles in two classes each match, ergo so many cases.

I measure my OAls as I go, adjusting the OAL of each round to the exact length I have determined gives me the most accuracy, using the bullet puller if necessary. The need to do this is the varying length of the ogive slope, which exists in all makes of bullets I have ever found. Our seater stems use the tip of bullets when pushing the bullet during seating. If stems were larger in diameter and touched the bullets closer to where the bullets will engage the lands we would have much better, more consistent results. I had a conversation with an engineer at a die company about this issue. He said they know this situation exists but did not want to do the change necessary to correct it. I suppose inventories of parts, etc. complicates that reality.

I have not set the world on fire shooting over the years BUT I determined to try to give myself the very best chance of winning I could by making as near to perfect ammo as I could. Did it help me? I don't know but when one can see the results of exact ammo on paper in tests, why wouldn't one make ammo as near to perfect as they could. In my view, to do otherwise is to give up a small edge that may make the difference between winning and second place or between breaking records and only winning.

One's calipers with fixtures attached, (stony point) do not lie when it comes to AOL's, when measured correctly.

Keeping necks clean: Very difficult to do if a person uses a large number of cases. One needs to spend a lot of time at it but the more patina and or carbon that builds up in necks, the more erratic the seating becomes and the harder the necks get, the more inconsistent as well. A friend and I have explored this area and we found that the shiner they are, the more consistent and easier the bullets seat. I mean being able to see your face in the inside of case necks. The duller they get , the more resistant to seating.

After annealing, there will be a patina coating present inside necks. it polishes out readily. I haven't been involved in Centerfire shooting much the past two or three years. I fell in love with Rimfire Rifles again after about 15 years and they swept me away from CF. When I was last involved in the polishing process, we found it difficult to find the tools necessary to do it relatively easy but, as I say, I haven't been involved in a couple of years. But there is no doubt about the efficacy of polishing.

Pete
 
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One thing I learned about benchrest shooting a long time ago is that what works for one person does not necessarily work for the next guy. I know someone that did not clean the inside of one neck in 2010. It must not have made much difference to his program............he made the World Team and went to France. Could be he just got a few lucky shots.:cool:

Later
Dave
 
The age old, it seems, arguement

One thing I learned about benchrest shooting a long time ago is that what works for one person does not necessarily work for the next guy. I know someone that did not clean the inside of one neck in 2010. It must not have made much difference to his program............he made the World Team and went to France. Could be he just got a few lucky shots.:cool:

Later
Dave

There a lot of ways to skin a cat. Just depends on what one wants out of it is all. Sure, it is possible to shoot very well with carboned up necks for folks who jam hard all the time. that makes one solely dependent on powder. There is more to be gained than that, from my experience.

Pete
 
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