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Back-Boring vs Over-Boring!?

TGS Outdoors
Published on December 13, 2018
Category: Training & Techniques
Duration: 7:04

This video explains the technical differences between back-boring and over-boring shotgun barrels. While both increase bore diameter, over-boring is more common and involves a slight increase (e.g., 18.6-18.8mm), whereas true back-boring is a more significant modification starting from the chamber. Potential benefits like reduced friction and improved patterns are discussed, but the speaker emphasizes these gains are often marginal and marketing-driven, with some experienced shooters preferring standard bore sizes.

Tags

Shotgun Bore Diameter
Back Boring
Over Boring
Shotgun Performance
Ballistics
Shotgun Patterns
Choke
Shotgun Maintenance
Firearm Technology

Quick Summary

Back-boring is a gunsmithing process of reaming a shotgun barrel from the chamber to increase its diameter, while over-boring is a manufacturing method producing barrels with slightly larger diameters (e.g., 18.6-18.8mm). While claimed benefits include reduced friction and better patterns, these gains are often marginal and marketing-driven.

Chapters

  1. 00:09Introduction: Back Boring vs Over Boring
  2. 00:25What is Back Boring?
  3. 00:52What is Over Boring?
  4. 01:07True Back Boring Process
  5. 01:34Back Boring vs Over Boring Clarified
  6. 01:55Benefits of Increased Bore Diameter
  7. 02:28Perceived Recoil Reduction
  8. 02:46Denser Pattern Centers
  9. 03:01Marginal Benefits
  10. 03:215-Shot Wads in Overbored Barrels
  11. 03:48Consistent Gas Seal
  12. 04:01Wad Operation in Larger Bores
  13. 04:38How Far Can Back Boring Go?
  14. 05:14Contributing Factors to Patterns
  15. 05:31Wider Bore and Pellet Formation
  16. 05:40Other Pattern Influences
  17. 05:46Is It Worth It? Marketing vs Reality
  18. 06:06Rarity of Back Boring Today
  19. 06:17Conclusion: Not the End-All
  20. 06:37Final Thoughts on Marketing

Frequently Asked Questions

What is the difference between back-boring and over-boring a shotgun barrel?

Back-boring is a gunsmithing process where the barrel is reamed from the chamber end to increase its internal diameter. Over-boring is a manufacturing technique where barrels are produced with a slightly larger diameter than standard, typically between 18.6mm and 18.8mm.

What are the claimed benefits of over-boring shotgun barrels?

Claimed benefits of over-boring include reduced friction for slightly higher shot velocity, potentially denser pattern centers, and perceived recoil reduction. However, these gains are often marginal and debated.

Can standard 5-shot wads be used in over-bored shotgun barrels?

Yes, plastic wads generally seal well in over-bored barrels up to 19mm due to their ability to expand. Fiber wads may struggle to create a consistent seal in bores larger than 18.7mm or 18.8mm without specialized inserts.

Is back-boring a common shotgun modification today?

No, true back-boring is very rare today. Over-boring is a common manufacturing practice, but significant back-boring is a specialized modification performed by a few gunsmiths and is not considered essential by many experienced shooters.

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