Discussion in 'Reloading Forum (All Calibers)' started by Alex Wheeler, Jan 9, 2016.
I am finding the lands with a 6br case in a dasher chamber. What you said is exactly the problem. After talking to my smith I found my chamber is 1.555 which is why I kept feeling the hangup. Good call on trimming back a bit.
Hi Bob.. You must completely strip the bolt , that means no firing pin assy , no ejector , and remove the rear baffle (extraction ramp) you can leave the extractor hook on the bolt face but you must hook the case into it before sliding case into chamber.
You will need to reinstall the bolt handle itself and the large screw that holds the bolt on. Doing it this way there will be absolutely no resistance to closing if there is no contact being made by case or bullet. The only resistance you will feel is if the case is not sized enough or the bullet is touching.
I have been using Alex's method for years with very good success, but recently started working with a bullet, barrel combination that is giving me fits, so I'm asking what others are looking at for their "touch" measurement.
I paint my bullet on the set-up round with Dykem lay-out dye which really help in the definition of seeing the engraving from the lands. I strip the bolt, place the cartridge under the Sako extractor and insert the assembly into the receiver raising and lowering the bolt handle several times. I then extract the cartridge and measure the length of the marks created by the bullet scuffing on the lands with a digital caliper while viewing through a large lighted magnifier. I measure all of the marks length, ie. a 4 groove barrel would give you 4 marks. For the sake of conversation if those marks were .040 long, should I assume that my touch measurement would be B2O -.040?
To put another way, if my set up cartridge measured 2.680" B2O and the engraving marks were .040 long, then my touch measurement would be 2.640"? This would be my base measurement that I would reference for seating depth changes, throat erosion etc..
Any thoughts would be appreciated.
No, the length of the marks do not correlate to the depth your in the lands. The closer the lead angle matches the ogive shape the longer the marks will be for any given amount of jam. Two different shaped bullets both .010" in the lands will have different length marks.
Many thanks to Alex Wheeler for enlightening users to an excellent methodology! Having just used it, the repeatability is unbelievable! I vote he be awarded the next user “tip award”!
Then I would have to give the award the one who showed me this method. I learned it at Deep Creek. Tom Mousel suggested the video. Its not the Alex Wheeler method. Deep Creek method would be more honest, but maybe it came from PA.?? Who knows.
BUT, you are the one that is successfully getting the word out to an audience of at least 40,000 people! You have some credit due, Sir.
That makes sense, thanks Alex.
Your reply just reminded me of something. When the barrel was chambered, I had my "smith" go back in with a throating reamer to give me the most use of the capacity of the case, as well as keeping the BT bearing surface in front of the neck/shoulder junction. It is very possible that the angle of the throater and/or the profile of the bullet is contributing to the situation I have. Thanks again for the clarification.
I was wondering how this would work with a Tikka. With my Remington style bolts it is not an issue. The bolt handle is attached to the bolt body. With the Tikka, the firing pin holds the bolt handle in place. Remove the firing pin and the handle can slide in the dovetail. Would this not interfere with the sensitivity required to feel the touch?
Great Video Thanks Alex.
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