HK SL7 Roller blowback question

[SL8-4]

I bought an SL7 off a fellow CGN member many years ago, but never fired it much.

I'm thinking of selling it so I went out on the weekend for some test firing. It was fun.

One thing that puzzled me however is that the spent casings have black streaks on them and do not have the shiny brass look after being fired.

Is this a normal part of the blowback system?

Any advice would be great.

Here's a pic of a few casings:

 

[Jake1911]

Yes, can see the streaks from the chamber fluting leading all the way back to the groove

 

[enefgee]

Many (most?) roller delay guns have fluted chambers to ease primary extraction. It works so well on some that they'll function perfectly without an extractor. That's what you're seeing. The SL7 is a lovely rifle, but generally a bit hard on brass.

 

[SL8-4]

Thanks for weighing in. Yeah, I'm torn on getting rid of it. I have the quick-detach scope mount and put a 4x Nightforce up top to mimic a ww2 G43. See pic.

I like that I can put the scope in a shoulder bag (modern version of the ww2 system) and use the scope or not in the field. The HK battle sight is awesome and a big reason I'll consider keeping it.

I heard that not a lot of these rifles came in to Canada...do you know anything about that?

md

 

[johnl]

Beautiful rifle you got there, too bad they’re restricted or I’d have one, also a SL6 is nice sadly restricted too

 

[sillymike]

The SL7 is a lovely rifle, but generally a bit hard on brass.

Well, that's an understatement... they're usually all get a dent in the ejection process.

 

[lerch641]

I heard that not a lot of these rifles came in to Canada...do you know anything about that?

mdView attachment 686947

HK 770's pop up maybe once a year. HK SL7 pops up maybe once a decade. Non-restricted SL7? I've seen 3 now, and one is mine.

I'd suspect the number is double digits for a NR SL7 in Canada.

 

[ArmedGinger]

The place I work at has two mags for an H&K SL7

 

[stickhunter]

HK 770's pop up maybe once a year. HK SL7 pops up maybe once a decade. Non-restricted SL7? I've seen 3 now, and one is mine.

I'd suspect the number is double digits for a NR SL7 in Canada.

I've owned two NRs, and one is the OPs . I agree with you --- the numbers are very low in Canada. I seem to recall that it was Century Arms who imported them and had the NR-length barrels specifically made (I'm presuming by H&K since they have the fluted chambers and polygonal rifling).

Oddly enough, I had an SL6 (223) that was, for all intents and purposes, identical in form and function to the SL7 except that it had no fluted chamber and the rifling was standard land-and-groove. I didn't think it was a rebarrel as the outer finish (colour and machining) was identical to my SL7s, but who knows? That rifle would regularly pull the heads off of steel-cased 223.