Rock River X-1 sometimes not cycling using IMR 8208 BR

T

tank1949

Moderator
I have been shooting 168/150 grain Hornady MATCH HPs in Federal cases, CCI LR primers to work up loads. Most accurate 168 is 41 grains but I had a couple of rounds that didn't cycle new rounds correctly. Hogdgon max is 43.3 grains

Most accurate 150 is 41 grains of 8208 as well (weird) . Max load (150 Nosler Bal Tip)is 44.5

I am more concern why bolt didn't cycle correctly on the 168 grain rounds. I use dillion sb case sizer and trimmer and then resize brass again using sb RCBS to also de-primer brass. I deburr all case mouths. If anyone has a suggestion, please respond. Thx
 
Bolt closed in battery after last round fired of 5 round string. It should have came back and stopped. Magazine lip was supposed keep bolt from closing. All my RR magazines are new and I have never had a problem during earlier range visits. I didn't see any anomalies concerning rifle or magazine. It is possible that I may have jarred magazine loose, but I doubt it. With ammo components so expensive, including range visit prices, I don't want to waste ammo and make unnecessary trips. Thx!
 
OK, first point, its the magazine follower, not the feed lips that engage the bolt hold open.

90%+ of the time, when the bolt doesn't lock open when empty the problem is with the magazine follower or the bolt catch or the fit between them.

Rarely, a round can fire and eject without pushing the bolt back far enough to allow the catch to engage, but its rare, and its a "right on the edge" thing for this to happen without other issues showing themselves along with it.

You only had "a couple of rounds" do it, last round in the mag, each time...
Your mags are new, you said, so might just be a little sticky...

One way to test is to take the "problem" load and shoot some, putting only one round in the mag, each time. If the load is underpowered it should do it (malfunction) every time. keep track of the mags, is it only one where it happens or does it happen with any or all of them??

Not locking open when empty is annoying but its not a crash and burn failure.
 
I played around with 8208 in my gas guns and the only suitable use I found for it was 75/77gr loads in my 223s. I know I tried it in my 308s and gave up on it for some reason (accuracy, velocity or wouldn't run the bolt) but what it was I can't remember now.
 
I totally agree with the follower explanation. In addition, I had one round that didn't completely go to battery because bolt didn't completely close after it stripped round from mag. Other following rounds would close correctly. At the time, I suspected that I hadn't resized that specific brass correctly. But, I don't see how that was possible, since I had to de-prime using SB dies, after resizing and trimming via Dillion. I later pulled bolt face but could not see any particles that may have cause a failure to close. I was hopping to see perhaps a piece of rim has sheared off and caused the issue. The brass's rim looked fine too. No popped up primer either... After cleaning breach with chamber brush, the specific failing round closed by bolt correctly. I have since cycled numerous rounds through the specific magazine that may have failed, but I cannot duplicate issues. If I were a betting person, I'd bet that some kind of trash caused my issues. I never had this type issue with my SA M1A. Thanks for replying.
 
I went to range again this week and rifle performed flawless. I suspect, but cannot prove 100%, that my jury-rigged "led-sled" and shooting bench may have somehow dislodged magazine from rifle during earlier range visits. Therefor, magazine follower wouldn't or couldn't engage bolt. I also noticed during reloading brass that RCBS case lube was getting and sticking into some of my 308 case mouths and causing powder throw weight irregularities. Powder grains would stick to lube that somehow got inside cases. I used q-tips to clean case mouth and weighed powder twice (just to be sure). 41 grains 8208/168 HO match is the most accurate load and 44 grains 8208/150 SMK seems to be the most accurate. Ironically, with my rifle's 1x10 twist, the 150 SMKs seem to provided better consistent accuracy. I use a case lube pad to apply case lube and roll brass onto the pad. I may have used too much lube?
 
Sounds like too much. It is probably migrating up around the shoulder during resizing. Be aware you can just dip the neck in powdered graphite or motor mica. You don't have to apply the sticky lube up that high, though it is fine to do so if you keep it thin.
 
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