I looked through my vintage ads and this is the earliest "Heavy Breech" ad I found. 1884 L.C. Smith Maker, Syracuse

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I have an 1899 Baker Gun & Forging ad touting their "wide heavy breech" on the hammerless.

The earliest Ithaca "double thick nitro breech" ad was 1901 with the introduction of the Lewis model. I don't have any Crass ads with that statement.

Lefever went another direction. This is from 1903. "No thicker frame than an ordinary hammer gun."

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