Low Velocity Lead Bullet Chronograph Data

In the beginning there was a question, and it was interesting - can one define the necessary and sufficient conditions such that hard cast bullets will shoot well from Marlin lever-guns with Microgroove barrels? That was 1996.

Thirty thousand bullets launched downrange later, we concluded that we had a reasonable handle on the question. In 1999 we published our small treatise on the results and topic - Modern and Historic Developments in CAS velocity loads "The Use of Pistol Powders in Rifle Cartridges" .

Since then another 50k bullets have been launched downrange. Some might say to confirm and further refine the previous observations; others might say it's been entirely in pursuit of the "art of flying slow", yet others might argue that it's all been an effort to more finely tune the gmdr internal ballistics predictor [an IBP specifically designed to predict low pressure and low velocity loads]. Maybe there's a bit of truth in all.

The data on the attached pages represent a record of what we saw - the good, the bad, and the truly ugly. Reiterating: the data on the attached pages is chronograph data, ie, these are the components we used, this is the firearm, barrel length and twist, these were the ambient conditions, and these are the results.

This data is being offered as is, and for the benefit of those wishing to study internal ballistics (but without having to bear the cost of generating the necessary data).

If the reader chooses to reproduce any of the experiments, they do so strictly at their own risk. If one is looking for reloading/handloading data, please consult any of the various reloading manuals published by the powder and bullet vendors. If one is looking for internal ballistics data, from which to learn, then read on.

Data Taking Context/Conditions
The data for each data page was taken with the bullet specified for that page, and with the components and firearm as specified on the cartridge description page. Cases were full length sized; powder charges were all thrown (RCBS UniFlow) after being calibrated to +/- .03gr. Components were bought in large lots to avoid lot-to-lot variances (primers in 10-20k lots, powder in 4 or 8 lb canisters, brass in 500 or 1000 lots). Ambient temperatures for data for a single bullet (within a cartridge) were limited to a 10 deg (F) range, or less; and to 15deg (F) limits across all the data for a cartridge. All cartridges to be fired were heat soaked at the ambient for at least 30 minutes before being fired. Test cartridges were typically fired within 1 week of being built/reloaded.

Data is for 10 shots per powder weight. The average velocity is the average of those datapoints passing a 3 sigma filter. The ES and SD data items are for the remaining datapoints. A front rest was used, the shooter's shoulder for the rear. Data-takers were all demonstrated .5 moa or better shooters. Group Sizes are for all 10 shots, but excluding called-flyers.

The early data (357, 41 44 mag, 44 38 spc 44 russian were taken using a PACT model 1 chronograph, subsequent data has been taken using an Advantage Automation modal "A" lab chronograph. The screens in both cases were those for a PACT 1. The AA chronograph data was taken to .01 fps, the PACT 1 fps, or .1 fps. The screen were positioned such that the midpoint between the start and stop screen was 10' 0" downpath from the muzzle [SAAMI standard position for taking muzzle-velocity data]..

The generated data was either real-time processed by At-The-Range, a chronographic system manager, or after the fact, again with ATR. Resulting data was stored in RCBS.Load databases, and presented using RCBS.Load.

The resulting data is listed by cartridge. Data within a cartridge is broken down by bullet weight and type. The context information for a cartridge and information about the history/lineage of a cartridge can be had by clicking on the cartridge name at the left. To access the data for a particular bullet weight/type, click on that title as listed under the desired cartridge.

Special Thanks
Firstly, to the Oregon Trail Bullet Company - without their fine bullets, their knowledge in the subject, their cooperation, encouragement, and enthusiasm for the results, this would not have been possible - many many thanks.
Oregon Trail Bullet Company, WebSite

And to Marshall Jones of Jones' Fort. They provided all the necessary gunsmithing, repairs, parts for repairs for the data taking; they were also the source for the primers and powers used in the data taking. If anyone is looking for fine gunsmithing or reloading materials at reasonable prices, we recommend them.
Jones' Fort WebSite

The acronyms used in the tables for the different cartridge components are:

PR : Primer,
OAL : cartridge Over All Length,
CM : Case Manufacturer,
TempF : temperature in Degrees Farenheit,
PT : Powder Type,
PW : Powder weight in grains,
Vel : Velocity in feet per second,
SD : velocity Standard Deviation in feet per second,
GS : Group Size in inches.

It is expressly and strictly the handloader's responsibility to know their firearms, reloading equipment, components, procedures and safety practices.
GMDR has no control over individual reloading practices, reloading components or the quality of the firearms in which the resulting ammunition will be used, and as such, assumes NO liability for mishaps of any kind resulting from the use or misuse of the engineering data presented on these pages.

Click on a cartridge title at the left to see information about that cartridge and the specific context information for that cartridge's data; Click on the bullet weight listed beneath each cartridge to see the data for that cartridge/bullet weight.