Clarifying definitions for Jump, Touch, Off, Jam and Push Back.

30br

Jerry, there is some great information on 6mmBR.com on the 30BR from start to finish. Hope this helps you. Charlie
 
What I do - -

Is do the hard jam thing and then keep pushing the bullet back with my seater until I can just barely see land marks on the bullet, polishing the bullet each time I use the seater. I generally find that @ hard jam I would be from .012" to .015" into the lands. ( I know this from doing this procedure for years and years.) I also know that .006" in has given me the best groups, pretty much, up hill and down. ( I record the OAL once I find what I call "KISS" and keep the test round in the box of bullets I used to make the test round to refer to in the future) I then put together test loads @ .02g increments. Depending on the powder I use. ( there are known accuracy loads for the 30 BR as stated in another post) I have two favorite powders I have used over the past 10 years that have given me the best results with my 30BR's, H-4198 and Reloader 7. They seem to be quite close in their performance. What I have found is certain barrels will have a particular preference for one of those powders, depending on which bullet is used. The barrel I am currently using has shown the best results to date when using Re-7 with a batch of Fowler bullets I bought several years ago. They haven't worked particularly well in any of the other barrels I have tried them in, however. This is a 1-18 Krieger. I tried, for a long time, to shoot the short jackets in it but it does not like them much, with either powder. Unfortunately I only have about 100 of the Fowlers left :(.

I should have mentioned, I use a Stoney Point comparator attached to a dial vernier caliper to measure OAL's close to where the bullets will "kiss" the lands. I measure every round I load and pre-load for every match. If I shoot poorly, it's my fault :).

I have found that each barrel will usually like something different from the others. In all the years I have been shooting 30's, I have only had a couple of barrels that would shoot anything I stuffed into them. Unfortunately, they don't last forever. Rimfire rifles are the same but if one can find a magic lot of ammo it likes and be able to buy a quantity, life is a lot easier as long as that lot lasts AND no loading for every match, no rock & roll while shooting.

Pete
 
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Pete, you say that hard jam is usually .012" to .015" into the lands. I don't have years of experience doing this so I need some kind of method to determine that value. The best I can think of is to do a hard jam and then measure the round from the ogive to the base of the round. Then find the "touch" or "kiss" point using the stoney point or the Sinclair tool and then measure from the oigve to the base of that round. Subtract the "kiss value from the "jam" value and that will tell how far the bullet is into the lands. Does that sound right? Supposed to rain tomorrow so I'll try that. I need to make a case for the Stoney Point. I have a tap that matches the Stoney point threads so that shouldn't be too difficult if I can drill out the primer pocket easily. But first I have to see if I can find the tap.
 
Jerry, don't over complicate this. There are only 2 measurements on seating depth that you need to know, hard jam( seating the bullet with the bolt) and how many .001's off of hard jam you need to be to make the gun shoot its best. Check this on every new lot of bullets and recheck jam every 1000 rd's to keep up with throat erosion.
 
steve stanley said:
Jerry, don't over complicate this. There are only 2 measurements on seating depth that you need to know, hard jam( seating the bullet with the bolt) and how many .001's off of hard jam you need to be to make the gun shoot its best. Check this on every new lot of bullets and recheck jam every 1000 rd's to keep up with throat erosion.
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Steve, if you keep backing off of jam looking for the sweet spot, do you care to know when you transition from "into the lands" to "jump"? I'm about .020 off in this instance without hitting a sweet spot.

Also, I can't help myself. I over-complicate everything. I feel a need to fully understand what's going on. If something goes wrong and I can't figure out why, I have a terrible time letting it go.
 
I don't see why you need to know where the bullet is in relation to the lands. Sure, folks think that's important but another day, another range, etc....it may not be. If you're not shooting well enough for what you've got yourself into - change something. It's really that simple! Nobody is going to find the answer - nobody.
 
Wilbur said:
I don't see why you need to know where the bullet is in relation to the lands. Sure, folks think that's important but another day, another range, etc....it may not be. If you're not shooting well enough for what you've got yourself into - change something. It's really that simple!
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Wilbur, I enjoy reading your posts - in fact, when I see you've posted I usually make sure to read. :)
 
Don't know for sure how to take that...but I'll take it as a reason to keep on posting. I'm getting a little bit "crippled" in my thoughts, as well as otherwise, and someday you may have to say...Wilbur, please quit posting.
 
To the over-complication deal

It's not over-complication as long as you know your rifle might shoot better, at a given time, if you change the seating depth. Knowing exactly how much you changed it may not be over-complication if you use the seater stem for measurement. It's easier to "measure" and is the same thing. There is nothing really over-complicated about what you're doing but rather how you're thinking about it....it seems.

There exists in this world...rifles that will shoot (win) at any seating depth and rifles that will not shoot (lose) at any seating depth. Also, there are rifles that will win today and lose tomorrow - at any seating depth. Go figure!
 
Found it

Found the tap I needed, so I took it, a couple of cases, and the case holder over to my shop. Set the case holder w/case in my mill vise, dialed in the flash hole, drilled and tapped and, viola, a modified case. Threaded perfectly onto the Stoney Point tool. Now that I've patted myself on the back, time to use it and see if it helps me. Only the Shadow knows what evil lurks in the minds of the shooting gods.!
 
adamsgt said:
In this case, Quickload seems to be a bit low. It estimated 2954 fps for 34.1 gn while the actual was 3006, 3013, 3019..
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I don't know anything about Quickload but I doubt 75 fps is even in the within the true accuracy of your chronograph however Quicklads numbers sound good too me . I have shot more than 15,000 rounds of 30 BR and I would say just jamb it hard into the lands see what it does and start backing it out. The 30BR likes lots of neck tension and being buried in the lands. I wish it didn't as it is inconvenient but every time I try to jump the bullet I end up back buried in the lands. Oh and as Steve Stanley said in most cases or I should say barrels it is impossible to get too much H4198 in a 30BR case.
Dick
 
adamsgt said:
............Only the Shadow knows what evil lurks in the minds of the shooting gods.!
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The Shadow doesn't know either....and you can call them "shooting gods" if you wish but I do know that at least one person calls them something else. Perhaps that person should reconsider....
 
Thanks Dick

Dick Grosbier said:
I don't know anything about Quickload but I doubt 75 fps is even in the within the true accuracy of your chronograph however Quicklads numbers sound good too me . I have shot more than 15,000 rounds of 30 BR and I would say just jamb it hard into the lands see what it does and start backing it out. The 30BR likes lots of neck tension and being buried in the lands. I wish it didn't as it is inconvenient but every time I try to jump the bullet I end up back buried in the lands. Oh and as Steve Stanley said in most cases or I should say barrels it is impossible to get too much H4198 in a 30BR case.


Dick
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I just finished priming fifty cases to do some more testing. A couple of days ago I did some tests starting at "touch" and working my way towards "jam". Well, I started at the wrong end. Didn't see anything useful till I got about 6 off jam. I wasn't varying the powder charge, just the seating depth. I ran it all with 34.1 H4198. I've got bushings from .324 to .327. I used .326. This gun has .332 neck and the brass is .010 on the neck. Right now the brass is sized with the .326 bushing. I could pull the decapping rod and change the bushing to .325 or .324 and resize the necks. What do you think?
 
Dick Grosbier said:
Well if you really want to know what I think, I think you should try the .324 bushing and perhaps a little more powder, about half a grain.
Dick
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Well Dick, you've got 15000 rounds under your belt and I've got around a hundred so your opinion is a lot more valuable than mine. I'll give your suggestion a whirl.
 
I was running through some past post and truly needed this one. Thank you guys again
Tom
 
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