doublegunshop.com - home Forums General Discussion Classic & Custom Single Barreled Sporting Rifles @ doublegunshop.com unusual bolt treatment

Yes, that's sort of what I have always figured. It is for form, not so much function with the latter being sort of lamely ascribed to oil-holding capabilities.

If anyone has pictures of a large scraped area, I would love to see them. Scraping a whole breach block can only be for looks as very little of it rides against the receiver and smoothness is not particularly important up to a point.

Remington used to jewel the bolts on factory Model 700's. Not sure if they still do or not. Jeweling or scraping on surfaces that don't make a friction contact is obviously decorative. But on friction surfaces scraping or jeweling is very functional, and works well to reduce surface area and friction.

I would suspect jeweling and this style of 'scrape' finish on the bolt body is for appearance. Aren't these treatments very thin. I'd think if metal surfaces bear against each other the pattern would rub right off.

One maker that regularly uses jeweling is Westley Richards. Over the summer on their blog, they commented about some new four bore locks, and the jist of it was about the effort it took getting the appearance right. The coverage is clearly on non bearing areas. Similar comments about their bolt rifles. It just struck me as a current example of a builder using the effect as part of their embellishment decision, rather than functional.

Steve, wouldn't machine tool ways be scraped to increase the surface area contact?

Ways on machines are scraped for different reasons. Older machines are scraped to bring things back true and remove wear. The type of scraping I was referring to is similar to the bolt pictured in that it is meant to reduce friction.

It doesn't take much depth to reduce friction, and it takes decades of shooting to wear even very minor depth off. I've got an old Rem. 700 varmint rifle that has the jeweled bolt. I haven't a clue how many thousand rounds have gone through it, and the jeweling on the bolt barely shows wear on friction surfaces.

Maybe there is far less actual contact area than you think. The breech bolt on a Pigeon Grade Model 12 Winchester shows contact in a very thin stripe to nothing at all, depending on the particular gun.

Besides the decreased surface area and lubricant retention for friction, a textured surface (by whatever method) would retain oil for rust prevention. Manufacturing metal parts which will make contact with other parts with given tolerances still leaves a lot of guess work of how the pieces will fit and bear against each other in use. If a machinist only textured the area he thought would rub against another in use, the textured area would look strange, thus texture the entire area or part and make it more aesthetic. Imagine how a bolt would look with only the areas that rubbed jeweled.

Just for me, I'd back up and look at the original bolt picture or another example of a jeweled bolt. There are surfaces that I see that would benefit more from rust prevention than are typically covered.

I could see where reducing the surface area might decrease friction, but I'd think the high points were already well fitted and the dips done in a controlled manner. Less surface area to me would mean quicker wear, and the texturing never seems to be on the surfaces that're designed to bear.

I have seen instructions that generally comment about friction reduction and retaining lube, but then warn about keeping the abrasives away from lugs, cams, sears, pivots, etc. These are only thoughts, maybe I'm biased because I don't care for the appearance overall.

the "less surface area" argument doesn't make much sense to me.

Consider a file.

I think of it as aesthetics and nothing more. But it is interesting to see the different perspectives. I would really like to see more examples of scraping.

Fred, isn't it time to offer up your explanation?

I brought up a Michael Petrov thread that pictures some chasing, both on bearing and non bearing surfaces.