Hi all,
Quick question, does changing the C.O.L. effect pressure & muzzle velocity?
If so do calculators exist that help work this out?
Thanks,
Mick.
Effects of C.O.L.
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All handloading data posted on Full-Bore UK from 23/2/2021 must reference the published pressure tested data it was sourced from, posts without such verification will be removed.
Any existing data without such a reference should be treated as suspect and not used.
Use reloading information posted here at your own risk. This forum (http://www.full-bore.co.uk) is not responsible for any property damage or personal injury as a consequence of using reloading data posted here, the information is individual members findings and observations only. Always verify the load data and be absolutely sure your firearm can handle the load, especially older ones. If in doubt start low and work your way up.
Effects of C.O.L.
Infidel
Re: Effects of C.O.L.
Yes.
The closer the bullet to the leade the higher the pressure. This is one of the reasons that many off the shelf rifles have long throated chambers, often in excess of SAAMI dimensions (especially firearms of American manufacture). Not sure of any calculators out there for this.
The closer the bullet to the leade the higher the pressure. This is one of the reasons that many off the shelf rifles have long throated chambers, often in excess of SAAMI dimensions (especially firearms of American manufacture). Not sure of any calculators out there for this.
Re: Effects of C.O.L.
I am not aware of any calculators either and even tools like Quick Load do not take into account the jump or jam of the bullet with none SAAMI/CIP chambers.
Re: Effects of C.O.L.
Ok, thanks guys.
It was the lack of reference to C.O.L. in QuickLoad that prompted the question.
It was the lack of reference to C.O.L. in QuickLoad that prompted the question.
Infidel
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Sandgroper
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Re: Effects of C.O.L.
I use Silhouette Ballistics http://home.comcast.net/~jesse99/interior.html - you can adjust the COAL/seating depth and see the effects. According to the results, a shorter COAL increases the pressure with a given weight of powder compared to a longer COAL - see this article for more info http://bulletin.accurateshooter.com/201 ... -to-ogive/
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The Cupcake Kid
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Re: Effects of C.O.L.
Surely there are (at least) two different answers to the original question?
1. Assuming the bullet is not going to touch the rifling, increasing COL with everything else being equal will generally result in lower pressures and velocities. Software like Quickload can be used to calculate this, assuming you have calibrated it with some real-world data first. Decrease the COL and the pressure and velocity will generally increase.
2. If you are starting with the bullet close to, or touching the rifling and increase the COL so the bullet is now jammed, then the pressure will certainly increase but the velocity may not.
1. Assuming the bullet is not going to touch the rifling, increasing COL with everything else being equal will generally result in lower pressures and velocities. Software like Quickload can be used to calculate this, assuming you have calibrated it with some real-world data first. Decrease the COL and the pressure and velocity will generally increase.
2. If you are starting with the bullet close to, or touching the rifling and increase the COL so the bullet is now jammed, then the pressure will certainly increase but the velocity may not.
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