long drop tube vs short
- Thread starter Chiquita
- Start date
okie
Gold $$ Contributor
please do that test and report back to us. thanks!
Thank you for the reply.
okie
Gold $$ Contributor
I honestly shouldve said that i do not know--sorry for being a smartaxx
dellet
Gold $$ Contributor
Depends on load density and type of powder, stick, ball, flake.
A load with 60% fill you probably won't be able to measure a difference.
A high density load that slightly compresses the powder with the seating of the bullet, may not even touch the base of the bullet with a slow drop. That will more than likely show across the chronograph and on target with some powders.
A load with 60% fill you probably won't be able to measure a difference.
A high density load that slightly compresses the powder with the seating of the bullet, may not even touch the base of the bullet with a slow drop. That will more than likely show across the chronograph and on target with some powders.
Thanks for clarification. Being it may be a beginnrrs question I thought you were being sarcastic or didn't know. So I assumed the positive.
okie
Gold $$ Contributor
not a beginners question
H P White laboratory looked at this issue a long time back. (1950s?) IIRC it was written up in some NRA journal and I think I read about it in the NRA handloading book. 30-06 with a heavy bullet and case-filling bulky extruded powder was used and the exercise was to study the effects of charge compression v settling the kernels in the charge.
Plain compression produced no excessive pressure nor changes to ES compared to a 100% fill just touching the bullet base. IIRC light settling had no or little effect apart from reducing pressure on the bullet seating action. Heavy settling reduced MVs slightly and increased ES values. Very heavy settling (use of extra - long drop tubes and even more so with vibratory settling through the case-head) decreased MV and increased ESs significantly.
The reason attributed for these behaviours was that simply poured coarse powders leave lots of gaps between kernels for the primer flame / ejected material to penetrate deep into the charge and start / propagate burning efficiently.
Compression of extruded powders within reason doesn't degrade this feature, but heavy settling does as it reduces the air-gaps between kernels. Really reduce them by vibratory machine settling and the primer flame has a harder job penetrating the charge and/or charge burn becomes less consistent.
Against that some sources such as Mic McPherson recommend a 'swirl pour' through the powder funnel which gives a degree of kernel settling, but more important sees extruded kernels aligned more consistently in the case-body. I've used this method for years, but can't say if it works in terms of chronographing 'with' and 'without' cartridges. I suspect you'd have to shoot and chrono' a lot of groups under identical conditions to see a change one way or another. But still .... who knows?
Ball type powders are a different kettle of fish in that they naturally align themselves with little airspace left within the charge column. This may be one reason as to why magnum primers are recommended (in addition to heavy surface deterrent coatings slowing ignition). It used to be common to read in loading manuals and elsewhere to avoid heavily compressed charges with this powder type, but with the sole exception of the Norma Reloading Manual this advice has disappeared over the years. Norma says to avoid it as compression closes the already small gaps up even more degrading primer flame penetration.
(A good example of problems from really heavy ball powder charge compression is the saga of early .458 Winchester Magnum dangerous game cartridges back in the 60s. Stored cartridges saw the vast degree of compression that the factory had imparted - in order to push a too-small case design up to African DG cartridges ME levels with contemporary powders - force the powder kernels to fuse together degrade performance, in extreme cases producing impenetrable powder clumps and resulting hang/misfires, squib loads. Reducing loads and hence the amount of compression solved the problem but at the expense of significant MV/ME loss until ball powder performance caught up. Winchester had developed and launched the cartridge without problems with 'fresh' produce, but it was later discovered that the effect occurred when storage took place and lasted a year or two.)
Plain compression produced no excessive pressure nor changes to ES compared to a 100% fill just touching the bullet base. IIRC light settling had no or little effect apart from reducing pressure on the bullet seating action. Heavy settling reduced MVs slightly and increased ES values. Very heavy settling (use of extra - long drop tubes and even more so with vibratory settling through the case-head) decreased MV and increased ESs significantly.
The reason attributed for these behaviours was that simply poured coarse powders leave lots of gaps between kernels for the primer flame / ejected material to penetrate deep into the charge and start / propagate burning efficiently.
Compression of extruded powders within reason doesn't degrade this feature, but heavy settling does as it reduces the air-gaps between kernels. Really reduce them by vibratory machine settling and the primer flame has a harder job penetrating the charge and/or charge burn becomes less consistent.
Against that some sources such as Mic McPherson recommend a 'swirl pour' through the powder funnel which gives a degree of kernel settling, but more important sees extruded kernels aligned more consistently in the case-body. I've used this method for years, but can't say if it works in terms of chronographing 'with' and 'without' cartridges. I suspect you'd have to shoot and chrono' a lot of groups under identical conditions to see a change one way or another. But still .... who knows?
Ball type powders are a different kettle of fish in that they naturally align themselves with little airspace left within the charge column. This may be one reason as to why magnum primers are recommended (in addition to heavy surface deterrent coatings slowing ignition). It used to be common to read in loading manuals and elsewhere to avoid heavily compressed charges with this powder type, but with the sole exception of the Norma Reloading Manual this advice has disappeared over the years. Norma says to avoid it as compression closes the already small gaps up even more degrading primer flame penetration.
(A good example of problems from really heavy ball powder charge compression is the saga of early .458 Winchester Magnum dangerous game cartridges back in the 60s. Stored cartridges saw the vast degree of compression that the factory had imparted - in order to push a too-small case design up to African DG cartridges ME levels with contemporary powders - force the powder kernels to fuse together degrade performance, in extreme cases producing impenetrable powder clumps and resulting hang/misfires, squib loads. Reducing loads and hence the amount of compression solved the problem but at the expense of significant MV/ME loss until ball powder performance caught up. Winchester had developed and launched the cartridge without problems with 'fresh' produce, but it was later discovered that the effect occurred when storage took place and lasted a year or two.)
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