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Do you have the bushing set so you can measure or the ogive instead of the tip? The shoulder should not affect your measurements. you are measuring from the base of the case to where the bullet touches the lands. This should be doable regardless of the shoulder.
The distance from the base of the case to the throat should never change(except for throat erosion obviously) just like the distance from the face of the bolt to the chamber should never change as it is fixed. Or should be Since your seater die does not touch the shoulder is will seat the bullet to a length in relationship to the base as it sits in the shell holder. As such when you chamber the round the base of the case sits on the bolt face and the bullet should be the same constant distance from the bolt face regardless of the shoulder. The only thing that changes is the head space. I did a little experiment I took a fire formed case and a brand new case that has only been annealed. I ran a Hornady 208GR Amax That I pre weighed to within .1 gr and measure to be within .006 in lenght. Seated a bullet in both and came up with a OAL that was exactly the same using my LNL bushings. The heads peace was .005 off as this is on a brand new barrel with 25 rounds down the tube.That error was likely me not having the case perfectly strait in my calipers.
Now taking your original measurement is a different story if you have a very loose chamber and the modified case goes in further that your once fire brass that has been fire formed. This would obviously affect the position of the base of the case as it is not being controlled by your bolt. FYI Hornady will modify your case for you, which they recommend VS using one of their modified cases.
Ok. Got ya. That was my afterthought, but I was still wrestling with the whole concept. And yes I do have the bullet comparator so I'm measuring using that and not at the tip of the bullet. I measured a whole box of SMKs the other day just for the heck of it, and I found that the extreme spread in bullet length was about .012''!! Seems like quite a big spread.
Now if you used a modified case you need to measure the head space of that case and your fire formed case and take that difference into account when setting your seater die. Like I said when you use the LNL you need to account for head space as the bolt is not controlling the position of your case, the shoulder is.
Ok, so now you lost me again. I thought since the cases (both my fireformed brass and the LNL "modified case") would be the same length (what I would call "trim to" length) I would seat the bullets using a comparator to the same length as the measurement that I got from my OAL gauge.
No The case is head spaced off the shoulder. Which means without the bolt face to control the position of the cartridge when your modified case is in your LNL guage and you push it in the chamber the only thing that stops it is the case shoulder coming in contact with the shoulder area of the chamber. Now since the modified case will be sized to Sammii min spec more than likely and your chamber will not this means the fire formed case will have a shoulder slightly forward of the sammii min spec case. This means the location of the case base in relation to the throat will be different from your modified case to your fire formed case.
Or in simple terms your LNL measure tool will not located the case base in the same location as your bolt unless you use brass fire formed in your chamber. You can do one of two things. Measure your modified case and measure a fire formed case. Say the difference is .010, the fire formed case having the shoulder set further out. You will need to add .010 to you measurement to get the seating depth "correct". So say your modified case give you say 94.485 MM (what mine is on my .300 WM this also includes the shell holder so it will be longer than actual case length). Now you know your chamber produces a shoulder .010 further out. That means you will need to seat your bullet to produce an OAL of 94.495 to touch the lands.
Or send your fire formed brass off to hornady to have them thread it to fit in your gauge and dont worry about taking the difference into account.
Or Even better do what I do. Buy a seater that has a micrometer adjustment(actually i use the one that came in my hornady new dimension die and the micrometer adjustment attachment). Once you find the OCW then load 5 rounds with the bullet seated .020 in either direction and which ever groups best at I'd say 200-300 yards set your die to that length and move on with your life. After about 500-1000 rounds re take your measurement to account for throat erosion and re set your seater accordingly.
Check out some vids on youtube.
YouTube - How I set COAL in My Rifles‏
measuring headspace
YouTube - Hornady Headspace Gauge‏
OCW Overview - Dan Newberry's OCW Load Development SystemNOW I GOT YOU!!!! That was my mental block-----the bolt!!! I'm not using the bolt to chamber the LNL OAL gauge. I was getting hung up on that part, because I was not thinking about the fact that the bolt was only used in my cases. Makes perfect sense to me now. Thanks for you help. I will look at the videos. I have seen the bottom one about the OAL gauge, and I have to say it was pretty helpful. Now I have but one more question.....what is OCW? I will probably slap my forehead when you tell me. The ole brain is on vacation this weekend I think. Thanks again.
No worries. It works, and works well.Oh, ok. I have read that before, but I think I will revisit it and see if I can learn a little more. Thanks again.
