QuickLoad - Breech Seating

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  • Last Post 16 December 2016
Bud Hyett posted this 16 December 2016

Extrapolating from a single data source is not good science. Attempting to simulate the .32-20 cartridge when breech-seated, I entered a value of “zero” for the seating depth and continued.

The Lyman dropdown menu lists the  323471 bullet which I used this past year. Using 9.0 and 9.5 grains of Accurate Arms #9 in the calculations, the resulting trajectory data closely approximates the data from match shooting.

My question is; “Has anyone else done this using QuickLoad? Specifically, using “zero” for  seating depth as an approximation of breech-seating."

 

Farm boy from Illinois, living in the magical Pacific Northwest

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SierraHunter posted this 16 December 2016

I'm not sure that entering zero would be the correct data. In my experiance, breech seated bullets go into the cases some when the case is chambered in the gun.

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R. Dupraz posted this 16 December 2016

"..............  breech seated bullets go into the cases some when the case is chambered in the gun''

 

 When breach seating for my 32-40 and 38-55, the seater is adjusted so that the bullets are full in the bore and 1/8” ahead of the case mouth.

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frnkeore posted this 16 December 2016

Most everything that I use my QL for is BSing. In chronographing loads against QL, I've found that some data is close but, some data can be close to 100 fps off.

 

You have to be diligent when using QL, making sure all the perimiters are covered. One thing that bares verification, is case capacity. You should check the length and water capacity of your brass, against what QL has for that capacity, as well as the distance that your BSer sets the bullet in the barrel (back of BSer case to the front of the BSing rod). One more thing, is you have to match the bore area of your barrel to what QL lists for the program.

 

To check trajectory, you also need the bullets BC, in Bud's case, the BC of the 323471 is well known but, most single shot guys, have no idea of what the BC of their bullet is. Bud, are you using a GC on the 471 or did you take that off of the mold? I used the 471, back in the early 90's, BSed in a 32/40, shooting CBA matches at 2150 fps. Lots of sizing to be done and lots of recoil ></p>

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SierraHunter posted this 16 December 2016

Very interesting. I only played with breach seating very little in a 6x45.

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Bud Hyett posted this 16 December 2016

This is a good observation. The seater does set the bullet forward of the cartridge case. That means there is more volume for QuickLoad to calculate. Setting a negative value in QuickLoad will move the base of the bullet forward into the leade. This approach will be my next research steps.

You are right about case capacity checks. Not only in cast bullet loads, but the jacketed bullet loads also. I find QuickLoad to be close and a good tool. The Starline brass is heavier meaning thicker walls and thicker base. I need to learn how to add a new cartridge to the dropdown menu, the .32-20 CPA and use the thicker walls as a default value.

I have the breech seat bullet that CPA sent with the rifle plus another adjustable breech seat tool. More ways to experiment and compare. 

Farm boy from Illinois, living in the magical Pacific Northwest

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SierraHunter posted this 16 December 2016

I've wanted to try quick loads for a long time, but do not own a computer, and they do not offer it for mobile devices for whatever reason.

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