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How do you determine "at the lands" by your method?

 
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  #15  
Old 05-23-2004, 08:19 PM
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Re: How do you determine "at the lands" by your method?

I use a FL sized case and split the neck with a dremmel.

Len,
If you're "careful", you can cut the coil spring back (cut off wheel in a dremmel works) incrementally until you get the desired plunger pressure, or simply remove it if you shoot single shot only like one of mine is. The factory spring is VERY high pressure, it will often dent the case mouth as it slips from the chamber and hits the inside of the receiver ring, and if you don't use an expander (I don't) in your die, you will have to then. The ejector itself is seperate from the firing pin assembly BTW.
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  #16  
Old 05-24-2004, 06:52 AM
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Re: How do you determine "at the lands" by your method?

Could you not do a chamber casting and get the measurement? I have to average the measurement with the stoney point tool also as I seldom get the measurement.
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  #17  
Old 05-24-2004, 09:57 AM
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Re: How do you determine "at the lands" by your method?

1. Sinclair and Stoney Point seating depth tools are usable if you understand the tools nuances and take repeated measurements. Buy one of them as both are around $30.

2. Jam seating and looking for marks will give you bout .040-.050 into lands. A place to start, but impossible to accurately measure throat erosion and adjust seating to accomodate. More commonly known as SWAG.

3. Stoney point comparator set ($26.50) for accurate dial caliper is essential for any measurement of seated bullet. Buy it first!!!

4. Unless AOL is issue, then above 1 and 2 is meaningless. What matters is you seat into the lands (even as deep as .040) tune until best groups with powder variances then tune for seating depth last. Fine tune depth at that point at .002 increments. Then make measurements of seated bullets with Comparotor. Which is the only measurement you need. Ie where does the gun shoot best.

5. All the above is meaningless again unless you are sorting bullets by base to ogive (spot on bullet where it touches lands) lengths. Sierra bullets from same box have varied by .030 on where ogive starts. Unless sorted kills any standard touching point of lands.

Custom bullets will vary as little as .003 in batch of 500, but can vary by as much as .020 from one lot to the other.

6. Quality inline or Micrometer seating dies are essential if you are serious about this.

7. RW Hart sells the best tool for sorting bullets and it is called the Buhay Ogive checker ($125 for one caliber). Zero variance with dial indicator under spring pressure. However, stoney point comparator ($30) clipped to caliper blade used to measure base to ogive is accurate as long as you watch the pressure closing blades.

BH
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  #18  
Old 05-24-2004, 02:43 PM
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Re: How do you determine "at the lands" by your method?

Ogive checking just came in within the last 2-3 years or so. So do it and some do not. I am not the Ballistics guru and tester that some are. Henry Childs on BR central (goes by HBC) is the leader in this.

He has done serious testing and says it really takes out lot of vertical, but more importantly "rounds" out the groups.

His big thing now is metplats. Ie uniforming them to standard length from ogive. Either the Tooley tool or the one from Kevin Cram (Montour Rifles). Cuts BC by .2% on average. Non uniformity can cause a 5% BC variance which is 6 inches vertical at 1000.

Tooley is cutting tips off and installing own plastic tips on some bullets.

Dave and Steve Shelp tested the new Clinch River 6.5 cal 140 grain "flatbase" bullet this weekend in Ohio and kicked butt. Think about 4 five and four inch groups for light guns. Seems to like a 9 twist barrel.

BH
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  #19  
Old 05-24-2004, 02:58 PM
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Re: How do you determine "at the lands" by your method?

BountyHunter

Please clarify. "Cuts BC by .2%", do you mean 2.0 % ?

.2 % is only taking a bullet from .750 down to .748
That's no bad.
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  #20  
Old 05-24-2004, 03:45 PM
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Re: How do you determine "at the lands" by your method?

These are obviously some of the finer points in handloading and I know I've heard plenty of people say they do it all, some for confidence, some say it all shows improvements.

I can't help but wonder what the difference would be if you took normal cafefully prepped brass, turned and such, no detail missed, then seated bullets that never went through any sorting inspection process and compared them to same load with bullets that had been through every uniforming procedure mentioned, even spun on the Verne Juenke ICC...

If there was an advantage of increased precision to doing all the work on bullets, one should see a the largest improvement by doing everything he could to one batch of loads and nothing to the other, although you would have to isolate the advantage contributed by each step if you wanted to eliminate any that might prove un-useful.

Has anyone done this sort of all or nothing comparison before? If so, what did you find and how confident are you other variables were not influencing the testing?
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  #21  
Old 05-24-2004, 04:43 PM
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Re: How do you determine "at the lands" by your method?

Len,After making my 4th different design Meplat trimmer i have settled on the tooley design with an easier adjustment set up..This is about as simple and efficent a product you can get and dave sells em for about 40 bucks i understand ..Just before our recent state champs i tested the 187BIBs with and without the meplat trimming..Results were cutting the bullet AOL back to 1.320 long from approx 1.325to 1.328 gave a loss of 3/4s MOA (down the paper) @ 1K..I don't know(care)what the loss in bullet speed at target that equates to..I do know that if you want to shoot sub 5 inch 10 shot at 1000yds unless you are a very lucky fellow then bullet equalization is paramount..We have completed 4 1K matchs at my home range so far this year ,my Agg for the 4 is 7.290 inchs..Also an added advantage in meplat trimming is after cutting it is possible to see if the ogive forming has put any folds in the jacket..JR..Jeff Rogers
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