The following video details how to anneal an SST or Interbond projectile as described amongst the cartridge texts of the knowledge base. Annealing can produce two benefits. In the first instance, it helps the jacket of both the SST and IB to swage back after expansion rather than over expanding. The reduced frontal area allows for much deeper penetration- but without sacrificing wound channel diameters. This process can for example increase the versatility of the .338 caliber 225 grain SST which if left unaltered, will on occasion over expand if fired from a .338 magnum and used on very large bodied deer at close ranges, resulting in shallow penetration.
In the second instance, at long range, the softer ogive helps to produce faster expansion, imparting energy more readily and improving wound channel diameters. This helps the Interbond to create broad wounding at ranges of around 400 yards in various calibers (as an example) while allowing the SST to produce admirable performance out to ranges exceeding 1000 yards depending on the individual bullet design versus game body weights.
Regarding the SST, please bare in mind, a high sectional density (long for caliber) SST is optimal for this process. For example, annealing the .277" 130 grain SST does not improve performance. Annealing the .277" 150 grain SST is a boon, making for a potent load in the .270 Winchester. As always, results are vastly dependent on impact velocities and game body weights (resistance). As a further example, annealing the 154 grain 7mm SST (almost the same SD as the .277" 150 grain bullet) helps improve expansion at extreme ranges but does not help penetration at close ranges if fired from a 7mm magnum and used on stout bodied game. Magnum muzzle velocities and close range hits are hard on conventional bullet designs. On the other hand, annealing the .277" 130 grain Interbond or 7mm 154 grain Interbond helps both projectiles to achieve deeper penetration and faster expansion. And as previously mentioned, annealing the 225 grain 338 SST can make a big difference in the .338 magnums.
There is a lot to consider. For example, a 7mm user may decide to use an annealed 154 grain Interbond for close to intermediate range work on Mule Deer, using the annealed 154 grain SST for long range work on the same game. Yet, another hunter may decide to choose the annealed 162 grain SST for all situations. As always, matching bullet weights to game body weights along with intended ranges and conditions is the first step in decision making.
Each caliber / weight SST must be studied on an individual basis (just as I have done with other projectiles throughout the knowledge base). Annealing certain SST and Interbond projectiles can radically optimize cartridge performance and many examples of this are given within the knowledge base.
For those who wish to delve further into this subject (beyond the information given within the TBR Knowledge Base), more information can be found in the book, The Practical Guide To Long Range Hunting Cartridges.
THE PRACTICAL GUIDES TO LONG RANGE HUNTING RIFLES & CARTRIDGES
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