Gunsmithing Brass shavings on boltface...

[Wannashootit]

.338 LM, 100 rounds down the tube. Nothing hot, been running 90.5 of H1000 under 300 SMK's, up to 92 during load dev. with no pressure signs on brass or bolt lift. Very fine "flakes".

Anyone seen this before? Possible causes?

 

[surgeon260]

If it's a new bolt, it might just be sharp extractor edges and a new extractor spring combining to take little chunks out of the case rims.

 

[Steel head]

If it's a new bolt, it might just be sharp extractor edges and a new extractor spring combining to take little chunks out of the case rims.

This.

 

[Wannashootit]

Thanks. I did think about the extractor, didn't feel any rough edges on it, or around the brass- but I guess can't hurt to hit the edges lightly with a cratex wheel.
Hadn't thought about the ejector- being new and tight, it certainly could be "filing" these very fine particles off the casehead- and that would explain why they're under the case (I didn't see how the extractor rubbing off the rim would could get flakes under the case).

Thanks again, guys.

 

[oldfatguy]

I see that on my Rem 700 223 and GAP Crusader 260 Rem bolt faces. 2,300+ rounds on the 700 and 1,300+ on the GAP. A couple of swipes with a brush removes it.

OFG

 

[XLR308]

Not sure if it's just the light or what in the picture but looks like you've got some pretty nasty looking grooves in the face of the bolt head.
Mainly on the extractor side.

 

[Huskydriver]

.338 LM, 100 rounds down the tube. Nothing hot, been running 90.5 of H1000 under 300 SMK's, up to 92 during load dev. with no pressure signs on brass or bolt lift. Very fine "flakes".

Anyone seen this before? Possible causes?

View attachment 7168805View attachment 7168806

Looks like shavings from your extractor as others have stated however....

92 grains of h1000 is a very hot load fyi with 300 smks. Those primers are looking pretty flat. Your def at the top end

 

[werew]

I think that's a Savage? A friend of mine and I both have .338LM FCP's and the bolt face surface finish is a "little rough". I've seen this condition in several other Savage's, in other cartridges and Savage rifle models also.

Load development for pressure signs with my .338LM went up to 92.8gr H1000/Berger 300 Hybrids/CCI250/Lapua brass... I noticed the light powder charges at the beginning (90gr H1000) were also scraping brass off.

My bolt face looked rougher than yours and required some rework. Don't do the rework if you're not comfortable/confident you know what you're doing. I'd contact Savage and let them know, they might ship you a new bolt head. I do not condone lying, but if you tell them(Savage C.S.) you shoot reloads they might not be so helpful. Hope this helps.

 

[carlsbad]

Your bolt face is rough. You can see the impressions of the machining marks in the primers. INdeed, that is a hot load bsed on primer flow.

 

[Supersubes]

The giant case head size of the Lapua generates more bolt thrust than small case head cases fired at the same pressures. This is gonna be a thing with all lapuas to some degree. Couple that with a rough bolt face and top end pressures...