Outer Edge Loading Guideline Summary
Important Note: Outer Edge Projectiles (or copper bullets in general) should not be seated any closer than 0.035” or 0.9 mm to the lands. Most copper bullets find optimal accuracy between 0.040” and 0.060” or 1 – 1.5 mm off the lands.
There are various opinions as to how close a bullet should be seated to the rifling lands. Until recently it was commonly believed that jacketed lead hunting bullets would shoot best seated somewhere between 0.010” to 0.030” off the lands. Over the last few years, extensive testing in the US has shown that even jacketed lead bullets seated with a 0.040” to 0.060” jump to the lands will deliver precision accuracy with loads that aren’t as temperature sensitive. Even VLD target bullets will often work better seated well off, rather than close to or engaged with the lands.
In Australia, precision target gunsmiths have been experimenting with chambers for ELR rifles with long throats, similar to the Weatherby line of cartridges for years. The chamber spec criteria are such that if the bullet is in this jump zone and there is still some bullet shank in the case neck, then precision accuracy with higher velocities may be achieved without necessarily increasing pressures. The moral of the story is; don’t get hung up about seating 0.050” or more off the lands.
The downside to nonstandard, long throated chambers is of course that long Cartridge Overall Length (COAL) cartridges may not feed through your magazine and are more susceptible to runout issues with rough magazine handling; so consider this carefully before going down that path.
Case Capacity – Outer Edge load data is based on a nominated case capacity for each cartridge. There are countless load recipes on the internet with meticulous detail about jump, powder, primer etc. but case capacity is often ignored. Please ensure you know the case capacity of your brass. The following is an example as to why it’s so important:
The SAAMI/Winchester standard for the case capacity of a .300 Win. Mag. is 93.8 gr of distilled water.
Remington brass has a case capacity of 88.0 gr; 5.8 grains less than the SAAMI/Winchester standard. Norma brass holds 95.5 gr of water. That is a 7.5 grain, or 8% range in case capacity. The implications for dangerous pressures here are obvious.
Whilst other cartridges may not have such an extreme range, it is important to note that even a small 2-3% difference in case capacity can make a big difference in pressure/accuracy outcomes.
1: Always start at the suggested starting load and increase slowly.
DO NOT EXCEED MAXIMUM LOADS.
2: Match the Outer Edge bullet recommended for your barrel twist. So if you have an 8” twist barrel, use an 8” twist bullet. It’s perfectly fine to use an 8” twist bullet in a 7” twist barrel.
Fast barrel twists will stabilise well-made slow twist bullets, but not the other way around. NB: a 1 in 7” twist barrel is faster than a 1 in 8” twist barrel.
The required twist is in the Outer Edge bullet product code as well as on the box i.e. 264 8 113 BBT provides the following bullet specifications data
i.e. 264 8 113 BBT provides the following bullet specifications data
3: Follow the load data suggestions in the data file on the Outer Edge website. Load data is based on a Cartridge Overall Length (COAL), brand of brass and/or case capacity, powder and primers specified. Using a different COAL or components can increase or decrease pressures substantially. Hand loaders should measure the capacity of three fired cases with distilled water and compare the results with the case capacity noted in the Outer Edge load data.
4: Only use one brand of brass to ensure consistent case capacity and neck tension. Trim to length, chamfer and deburr cases.
5: Set the Cartridge Overall Length (COAL).
In most situations with factory CIP or SAAMI chambers, both bullet drive bands will be seated inside the case neck. Simply follow the Outer Edge load data COAL specifications. Some longer throated or custom throated chambers may require the leading or first drive band to be outside the case mouth, especially when experimenting with the implications of bullet ‘jump’ for accuracy. Given that copper bullets generally prefer a ‘jump’ to the lands of between 0.040” and 0.060”, a 0.050” jump is a good starting point.
Note: the rear drive band must ALWAYS be inside the case neck.
If the COAL is extended further out than the specifications in the Outer Edge load data, then the powder charge may have to be increased.
Use caution when increasing any powder charge.
6: Note: if any component such as powder, primers or the COAL are changed from the initial load set up, then powder loads will need to be re-established from the starting point. This is especially important when substituting magnum for standard primers.
TIP: – to ensure component consistency, buy powder with the same batch number and primers in bulk from the same lot.
Here to help: Should the user have any issues loading OEP or require additional advice, then don’t hesitate to contact:
Steve Hurt – [email protected] or 0413 332 806