MY 24" 6.5 is unlocking early- solutions

[mongoosesnipe]

When I get a chance Ill pull the gas block again and see what it measures. I had this barrel custom profiled after I bought the DPMS lo pro gas block that is on it. So I had him leave the gas block journal the length of the DPMS gas block, so it would be best to stick with it anyway as I would have to have the gas block journal turned down to match the length of whatever block I was using and in that case I might as well go to a .750 Gas block and journal so it would fit.

You can use an adjustable gas tube instead of gas block... http://www.midwayusa.com/product/297...gas-tube-ar-15

[joker31]

Heavybuffers.com XH buffer and a Wolff Heavy Buffer Spring, works great for my 18"....perfect timing and empties all fall in a coffee can at the 4 oclock position.

[Bwild97]

It took all 3 devices to control the early unlocking for my rifle, Adj. gas block, Tubbs CWS, and a wolff extra power spring.

[WildBill3/75]

What are all the signs exactly? I have a 20" barrel with rifle length gas system. Running Tubb flatwire spring, m16 Bolt carrier, and 5.12oz rifle buffer. All my cases are extremely clean but I get half moon marks from the ejector on 1/2 of my fired cases using factory hornady 123gr amax ammo.

[WildBill3/75]

Think I will buy 1-2 H3 buffers just to play around with tungsten weights...doing the math 5 weights in the rifle buffer should bring the buffer to around 10oz which would still be a lot cheaper than one of the 11oz XH buffers.

[joker31]

The 11oz XH buffer and spring are $125, I'm using an AR-15 Carrier but I could have used a lighter buffer and a heavier carrier but I figured I would rather have the weight on the sprung side instead of in the moving mass. It seems like it is a softer recoil than using a heavier carrier to me, I tried both and I liked the combo I have. When I start using the suppressor I will be switching to a Noveske Switchblock or a similar system with an M-16 or JP Carrier if I have problems.

[WildBill3/75]

I'm thinking my problem is that the bolt is unlocking to early as I doubt the ejector swipes are from over pressure as the primers are not flattened.
So I just ordered 2 H3 buffers for $80 shipped...that's 6 tungsten weights. I will let y'all know how it turns out when they get here and I get some range time. Right now I'm thinking about dumping out all 5 steel weights and replacing them with 5 tungsten ones. That should really work as I already got an M16 carrier and Tubb flatwire...between the HBB on this thing and all this extra weight this is really defeating the point in getting an ar15 instead of the ar10 platform haha.

[WildBill3/75]

Well I currently have the buffer weighing a little over 10oz and still am seeing swipes lol. I might try adding the last tungsten weight to see if it does anything.

[rasp65]

WB What do the swipes look like could you show us a picture? If your boltface has some rough edges it will definitely leave a mark.

[NugginFutz]

It seems to me that WB is treating the symptom, rather than addressing the cause. The Half moon marks mentioned are quite likely from extractor pull. This is consistent with a bolt that is unlocking early. The usual suspect in such a case is an over-gassed condition, which is a common occurrence in the Grendel. Increasing BCG mass will dampen the reaction to the high gas pressures, but it can come back to bite you, if you decide to try different loads. For the cost of the two H3's you can install a quality adjustable gas block, which would likely resolve the issue. This way, you don't increase the reciprocating mass, which is a win, in my book. The other principal advantage to the adjustable gas block is that it offers the capability of tuning virtually any load you care to feed your thunder stick.

[WildBill3/75]

Rasp65 they looks similar to these shown here http://68forums.com/forums/showthrea...ss-help-me-out
It is caused from the bolt unlocking to early.
NugginFutz I think your right and that will be the only fix to this problem as I loaded up the buffer with all the tungsten weights which made it weigh a little over 11oz and I was still getting swipes.

[LRRPF52]

Any pics of your brass? The Hornady load is not a mild one, I can say that.

[WildBill3/75]

I'll try to get some up tomorrow but they look like the ones in the link(half moons)
I get them on all my reloads as well as factory ammo which makes me suspect unlocking.

[WildBill3/75]

brass.jpg

Top is twice fired brass(my reloads)
Bottom is once fired hornady factory 123amax loads.