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loading to the lands ?

rebs

I am shooting a Tikka T3x Varmint in 223 cal. with 77 smk bullets. I have a decent load worked up and am now testing seating depth. The following 2.893, 2.893, 2.901 and 2.908 from case base to ogive. 2.908 shows the best groups, the other three are close but not as good. Where can I go from here ? .005 off the lands is the best, can I go closer to the lands safely ?

I don't fully understand close to the lands, into the lands and jamimg.
 
Very close makes the load sensitive to any variation. I would stay away from the lands or seat into them( if you are not concerned about ever having to extract a cartridge and potentially spilling powder all over the place).
 
If it is just a range rifle i always start my load workup with a hard jam. Those berger VLD's like a jam. whenever you jam all those concentricity issues are eliminated. Back off your charge a little if you are.concerned about jamming and work back up. If you read a little about competition benchrest you will quickly lose your fear of the jam.

Now the hybrid and the match kings and other tangent ogive bullets like.a.little.jump

As was said previously that touch and other close to the lands seating depths just don't last. Throat erosion, carbon buildup many things can change. Now very experienced shooters who monitor the condition of their barrel and willingly know they are going to chase the lands are very sucessful with it. If it is what your rifle likes then you have to deal with it.
 
When you started your testing, what were the differences in seating depths. I am only asking because the Berger site has one hell of an initial spread.

I am kind of interested in your response because I just found the best seating depth from base to ogive in 223 73 grain bullets at 1.830 which is a far cry from what you have found
 
These are my test seating depths 2.893, 2.893, 2.901 and 2.908 measured from the case head to the ogive. 2.908 was the best groups. My chamber is 2.913
 
Fotheringill said:
When you started your testing, what were the differences in seating depths. I am only asking because the Berger site has one hell of an initial spread.

I am kind of interested in your response because I just found the best seating depth from base to ogive in 223 73 grain bullets at 1.830 which is a far cry from what you have found
Click to expand...

The berger test works great if you are trying to find a mag length COL. Believe me it does work.

But what i have found is if it is a range rifle you will probably find a seating depth much closer to the lands. I start with a jam and back off in .005 increments.

One thing you have to understand. Any dimension using a comparator is only accurate with that comparator. CBTO comparator dimensions are meaningless except for the person doing the measuring. Distance to touch, the lands or a hard jam with the same bullet have some meaning.
 
Richard Coody said:
One thing you have to understand. Any dimension using a comparator is only accurate with that comparator. CBTO comparator dimensions are meaningless except for the person doing the measuring. Distance to touch, the lands or a hard jam with the same bullet have some meaning.
Click to expand...

Not only can there be a difference between comparators, there can be a difference between calipers . . . especially if one is using the cheaper ones. But they can still be useful in the same way comparators are.
 
^^^^^What Coody wrote. Your measurements are meaningless to anybody else. Difference in barrel chamber reamer, measuring equipment, bullet lot, the list goes on.

The only thing that matters is that you have a bullet proof (pun intended) way of finding lands in YOUR barrel, with your lot of bullets and your lot of brass sized in your dies and measuring it with your tools. It's the same with all your reloading equipment, your weights and measurements are applicable to you only. Any other shooter's numbers should be considered a basic guideline.

One way to verify that you are indeed in the lands is to remove the bolt and place a loaded round (or identical dummy round) into the chamber a give it a firm push with a wooden dowel. Then tilt the barrel up and see if the round drops out on its own. If it does, chances are pretty good you're not loaded into the lands.

To answer your question, yes you can go well into the lands. .005 inch into or off the lands would be a worthwhile test if the bullet seems to prefer being closer to, rather than further away to the lands.

You might be well into the case with that 77MK. I believe it was developed for AR-15 chambers with a deep throat. Are you crunching powder while seating the bullet?

I couldn't get a 69 gr Lapua to seat any shorter than .005 into the lands with 25.2 of Varget as it compressed the charge enough to push the bullet back out as I would seat it. Had to drop down to a lower node with less powder, but it shot killer groups today!
 
rebs said:
How much jump do the SMK's generally like ?
Click to expand...
They are very jump tolerant. The 69’s and 77’s were designed ( very well) for mag length in AR’s resulting in a healthy jump (especially in Wylde chambers). The 80’s are also very tolerant, shoot mine .025 off but was given some to test a few years ago that were about .050 shorter than that, shot a good score, shots right were called.
Great bullets, less tweaking more shooting!
 
Isn’t anyone else curious how he’s getting close to 3” long bto with a 223? Something sounds wrong to me with the measurements.
 
Richard Coody said:
If it is just a range rifle i always start my load workup with a hard jam. Those berger VLD's like a jam. whenever you jam all those concentricity issues are eliminated. Back off your charge a little if you are.concerned about jamming and work back up. If you read a little about competition benchrest you will quickly lose your fear of the jam.

Now the hybrid and the match kings and other tangent ogive bullets like.a.little.jump

As was said previously that touch and other close to the lands seating depths just don't last. Throat erosion, carbon buildup many things can change. Now very experienced shooters who monitor the condition of their barrel and willingly know they are going to chase the lands are very sucessful with it. If it is what your rifle likes then you have to deal with it.
Click to expand...
What would a hard jam be in thousands?
 
muleman69 said:
What would a hard jam be in thousands?
Click to expand...

For me a hard jam is just a datum to start seating depth test. When i use my stoney point i tap the rod lightly till the bullet is firmly seated in the lands. My measurements with my comparator will mean nothing to you but from that point i can back off the lands in measurable increments as i do my seating depth test.
 
Richard Coody said:
For me a hard jam is just a datum to start seating depth test. When i use my stoney point i tap the rod lightly till the bullet is firmly seated in the lands. My measurements with my comparator will mean nothing to you but from that point i can back off the lands in measurable increments as i do my seating depth test.
Click to expand...
Okay ,copy that. Thanks
 
I remeasured my ogive to lands and got
69 gr smk 1.909
77 gr smk 1.900
80 gr smk 1.922

I was surprised in the numbers for 69 and 77. I thought the 69 would have been a lower number than the 77. Does this look about right ?
 
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