Chamber Length And Patterns


Could you share your thoughts on chamber length as it relates to patterns. I have guns that have 2 3/4″ and guns that have 3″ chambers. I have patterned both and I can’t really say one is better than the other using ammo from the same box. This all leads to the question whether it will change something one way or the other to extend a chamber. In particular re-chambering a Browning 625 Sporting .410 from 2 1/2 to 3″.

Thanks in advance,



I don’t think that lengthening a chamber will hurt your patterns. All Krieghoff K-80s come with 3″ chambers in ALL gauges, whether for skeet or sporting. That includes a 3″ chamber for the 28 gauge and I’ve never run across a 3″ 28 gauge shell. Krieghoff is certainly known for optimizing its barrels for good patterns.

The new 725 Browning Sporter .410s have 3″ chambers too.

That said, I have not personally done a before and after patterning test on a 2-1/2″ to 3″ .410 conversion.

If I were to lengthen the .410 chamber, I’d be sure to also lengthen the chamber forcing cone while I was at it. If ever a shell needs a smooth transition from chamber to bore, it’s the .410.

I’ll bet that Briley would do the chamber lengthening for you and they probably have a useful opinion of the effect. They really do the work. I just parrot what other people say and what I observe of their efforts. You can’t go wrong going to the source.

Best regards,
Bruce Buck
Shotgun Report’s Technoid

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