Question on cartridge length consistency

Not that there is any question Uncleick knows where of he speak, but as more of a test it and then work from there type, all true.

I have had bullets seat back that I thought were ok, some would get into the lands and stick (if I tired to jack them out when a cease fire was called)

In reality it does not matter what your baseline of your seater be at the same point as your checker (I actually made my own insert of case shoulder bump back out of an insert for a caliber I will never use, it doe not match anything anyone uses but all I have to know is the shoulder moved back at least .001)

I don't zero out the mike for bullets, sure its an 1.004 longer than anything anyone else uses, but I am not using that in their guns, only mine. As long as I know its moved .0XX is all I care about (in or out)

I know where the lands are for any given bullet with that setup (logged and tested by actual bullets in a cartridge to where they stick in the lads not the Hornady throat unit that is about .015 short. I will use the Hornady and it case but also assume its short (and I check bullets to work)

I then adjust them back .020 (at least to start).

Any close than .010 I get random lands sticking. So no more than .015 close to my spec of sticking in the lands.

I am not close to Tubbs so I am not after the last tiny bit of precision. If I can shoot sub 1/2 inch groups with a good load, I am happy.

So what works for me is not Tubbs class but how many of us are.

I can always refine if that magic day happens!
 
My system in sizing an seating . Sizing , I'm using the standard RCBS Standard F/L sizing die with the Redding Precision shell holders . sizing my brass to .001space in my chamber . Seating I use the Redding competition seating die . My way of thinking is the case fits inside the sleeve from the shoulder to the shellholder with no slack . With the bullet on top of the case mouth raising the ram , the seating stem set for ogive setting . My thinking is the bullet side OD would stop at that point pressing the bullet into the case as the ram raises without the tip of the bullet hitting the top of the stem . How else could the ogive setting be exact , or am I missing something .
 
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That will mean base-to-ogive measurements for different rounds match at the ogive diameter where the Redding die leaves its little ring mark. That diameter, from my measuring, will not be the exact same distance to the bullet base from one bullet to the next, nor do we know it will be the same distance from the wider diameter ogive shoulder of the bullet that actually meets the throat, though I expect the bullet-to-bullet difference to be small. The problem is the bullets are the mixed output of more than one set of tooling and the toolmakers never seem to get quite exactly the same exact ogive radius established on each forming die.
 
Unclenick
Let's say the OD on the die at ogive ring is .305 for a 308 cal. even though the bullet may have a slight difference but stops at the .305 wouldn't that bullet from base to ogive ring be the same making the ogive to the lands the same ? I can see the bullet may be seated at slightly different depths . Tip of bullet to base was never a concern of mine , only base to ogive . When I measure my reloads with the RCBS Precision Mic all are dead on . I shoot with a .002 jump
P.S. I only shoot Sierra 168gr. HPBT MatchKing Bullets
 
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For the OP's sake I'd like to add ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Well nothing ;)

I don't care what anybody says , I still crack me up :D
 
Metal god
I understand completely , when everyone answers to help in every possible example . It opens up other ways of thinking , that opens up other conversations . That one post may help not only the OP but others like me . Im sure the OP can chime in when the post goes south . Don't you think if we were all in the same room , the same thing would happen . I could talk on this subject all day . Be Well , Chris
P.S. When I'm not shooting or reloading , I talk about reloading or shooting . There isn't many in my neck of the woods that do . So keep it coming.
 
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Don't you think if we were all in the same room , the same thing would happen . I could talk on this subject all day
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Absolutely , there is more info in this thread then the OP could have asked for . It's the great thing that happens when people that know what they're talking about , speak .

One of the best things about this forum .
 
Let's say the OD on the die at ogive ring is .305 for a 308 cal. even though the bullet may have a slight difference but stops at the .305 wouldn't that bullet from base to ogive ring be the same making the ogive to the lands the same ?
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Why would it? What dependency do the two have inside the chamber? The back end of the case doesn't determine how far forward in the chamber the cartridge and bullet go during firing. The headspace determining surface does that. Additionally, because the seating die doesn't push down on the bullet at the .305" diameter point, if there is a difference in ogive radius among the bullets in the box, it won't seat every bullet with the exact same head-to-.305" diameter ring each time, anyway.

Keep in mind, as we get down into the last thousandths of jump, we are probably wasting time better spent shooting. The reason I pointed these sources of error out is just to say we probably can't control the actual distance of the .305 ring from the lands reliably to better than about 0.005" (±0.0025"), cartridge-to-cartridge, by normal loading practices. As a result, someone thinking they are loading to get a jump of 0.002" (I've seen this claim made) is probably actually jamming the lands sometimes and not others. Therefore, any benefit claimed for such tight none-touching spacing is suspect and the group size is likely to turn out to be just as good seated another 0.005 in either direction. Or more.
 
As a result, someone thinking they are loading to get a jump of 0.002" (I've seen this claim made) is probably actually jamming the lands sometimes and not others.
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I think this would be an accurate statement , at least for me . I have a very accurate 168gr HPBT 308 load that measures 2.855 just off the lands . I estimate it to be .003 to .005 off the lands . I how ever believe maybe 1 in 10 to maybe 1-15 rounds I can feel slight resistance when closing the bolt which I believe is the bullet being pushed into the lands .

This load is my accurate plinking load . I say plinking because it does not use the "usual" known match components like match primers , Lapua brass , IMR 4064 , Varget or other powders everybody else uses for there best loads . It how ever may be the best load I've ever worked up as far as consistently preforming every time out .

I mention that because the fact I consider these a plinking load I've not tested if those rounds I feel get pressed in the lands shoot any different then the ones that I believe to be just off . They all go where I want them to so I've not found the need to find out .
 
Unclenick
I first size the case , I know the length of my chamber . What I did was strip my bolt on my Rem. 700 inserted a go gauge 1.630 then added shims the the base until the bolt closed with resistance 1.632 I did the same thing with a fired case an size the case to .001 headspace bolt would close with a slight hint of resistance to zero . I did the same with the bullet by seating it long an lowering the stem leaving no marks or resistance .Both measurements for headspace an base to ogive I now have , an can adjust my dies to give me the same .001 headspace an jump or jam settings every time . If I'm missing something , I don't understand why all my reloads are exact. The stripped bolt closures by feel for me is pretty accurate . What is your system . Chris
 
Metal god
I think we're on the same page , I use 3 different brands of brass , HSM , FC and ADI the powder I use is IMR 4064 My ogive measurement is 2.219 the OAL is 2.794 I have a Rock creek M24 5R barrel installed with hardly any free bore , big difference in the Rem. Barrel that I changed , it had so much free bore I just set the OAL to 2.800 an worked on powder charge. When thinking of jump or jam you would have to take into consideration your case headspace , Now I do feel sorry for the OP. Chris
P.S. My loads are on the low side of the scale 40.8 all my shooting is at 200 yards. Seems my other hobby is picking others brains . Thanks guys
 
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First Question: No need to trim unless the cases are so long they hit the lands. Trim to specs if necessary.

Second Question: Don't worry about it. Load them.

Third Question: If the case has been sized the neck is sized down to make the new bullet fit tightly. Again, don't worry about it, load them.
 
Jamaica
I don't think the case length could hit the lands , there is a range that the case is safe to load an a length to trim back. Jamesf553 is having an issue with loaded lengths . James hasn't chimmed in to let us know how its going . That's what we're here for .
 
Chris,

When I was experimenting with super exact bullet jump, my system involved this tool (sorry for the old blurry picture; I should take new ones), which is one of the first things I made after I got my lathe twenty-odd years ago (I did not make the cheap Chinese plunger indicator, obviously):

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The outside threads were to allow me to mount it in a press, but in the end, I mostly used it free-hand. The knurled bottom is the end of a case adapter that screws into the body to provide the correct chamber shoulder profile for a specific cartridge. It's .223 in the photo. Inside, the floating ram depressed by the dial indicator plunger resembles a seater die ram. The two parts, including lathe-turned threads on the adapter, were made in one workpiece to maximize alignment. It was drilled and reamed to nominal .220" bore diameter and then reamed with my .223 chamber reamer to form the chamber profile. I then parted the work at the junction of the freebore and case mouth portion of the chamber profile to make wiggle room for the plunger to move the ram. This way it meets a bullet at the actual location a real chamber throat does. The adapter at the bottom stops the case at the shoulder, same as occurs in a chamber and by then the bullet lifts the dial plunger via the floating ram.

In operation I put a finished cartridge in and hold it against the shoulder recess while I turn one of the markers or the dial scale zero to match the dial indicator hand position, giving me a comparison reference for the shoulder-to-ogive throat contact diameter distance. Subsequent cartridges then show plus or minus from that position, showing how much closer to or further from the throat they will likely be.

What I found with this tool was no advantage to perfectly exact seating depth. I was using the Redding Competition Seating Die which contacts and seats the bullet from a location above the location that actually meets the throat. Using new factory brass that I'd sorted with a case comparator to have the same head-to-shoulder datum length, was that a span of about 0.002" variation was pretty normal using Sierra match bullets. In other words, bullet ogive location varied between where the seater made contact and where the throat made contact by at least that much. If I didn't match the new brass, I got brass variation added in and was seeing at least another 0.001" in the mix.

In my experiments to try to see how much absolute precision mattered, I sorted my gauge's results so I could shoot identical and mixed length rounds, based on the indicator results. My thinking was that if it turned out to matter, I could use the instrument to sort the lengths and then adjust the micrometer head on the Redding seating die to do additional seating that set all those lengths to match the shortest length. But the matching rounds did not prove to shoot any better than the ammunition just left as it came off the seating die originally, so I gave up on this idea. I have a theory to explain why it didn't help, but let's leave that for another day.

A caveat here is that I was, IIRC, about 0.025" off the lands at that time. Would it have made a difference if I'd been trying to get 0.002" off the lands? I can't say. Someone else can try that. But the second factor in all this is that a case can undergo a little bit of sizing in the chamber. Hatcher showed .30-06 shortening as much as -0.006" just from rapid bolt work with an Enfield. It will vary with brass hardness and the gun, but it's a good idea to experiment with ejecting chambered live rounds to see if the length has changed, especially in self-loaders. I don't get a consistent result this way. Sometimes I'd get no clear change and sometimes another couple thousandths in the AR, indicating yet another potential source of error if you don't chamber slowly and carefully.

It seems like there's always something. But now I really am getting way in the weeds, again only to prove there's a limit to precision in the realm of seating depth, and for various reasons, so it's best not to count on it, but rather to accept this will be a slightly noisy aspect of the process.
 
Unclenick
I want to thank you for taking the time explaining your experiments , showing your gauge , absolutely amazing . I'm making You my go to guy . So if you see a post with Unclenick I need help , its me .
Respectfully , Chris
 
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