Fair Weather Rifles? What’s the issue?

[AMP!]

Well I finally decided to jump on the 6.5 creedmoor bandwagon. Built an AR10, she now has around 40 rounds down her. Curious if anyone else has these problems.

When shooting in normal 50-70 degrees everything worked fine. However, it’s about 15 F today and she won’t cycle Hornady Black for Federal Whitetale, and won’t lock back. It’ll eject but not pick up the next round.

Also, when I cycle the charging handle, she doesn’t want to go into battary half the time. I’ve gotta pull back and release a few times. No, I’m not riding the handle forward. Bolt lock release does the same thing.

I put three rounds of hornady Superformance through it without a hiccup. But the Federal and Black wouldn’t work at all. The same box of ammor worked fine a week ago. Is it possible it’s just the temp? The rifle and ammo did sit outside around an hour before shooting.

Thoughts?

 

[skatz11]

Are you using an adjustable gas block? I see this from time to time at cold 3gun matches. Some times shooters tune their guns to max in warm weather and then choke when it’s cold.

 

[lash]

I have to believe it’s the cold weather. I’m certainly no gas gun expert, but recently tuned my first gas gun assemble project and when using an adjustable gas block, it worked fine with one type of factory ammo but would do the same thing as yours with another brand.

Once I tuned the rifle to cycle the other brand, I was golden with everything.

Probably not coincidentally, the first load was also Superformance and the other load was match. Consider that Superformance is by definition a hotter load than many others.

If you have an adjustable gas block, tune it for the lighter load. If not, change your buffer to a lighter buffer to cycle in the colder temps.

 

[lennyo3034]

What lube are you using and how much? Cold weather can change its viscosity and slow down the carrier significantly.

 

[AMP!]

I do have an Adjustable gas block. SLR, and she was wide open. I’m using slip 2000 EWL. JP standard silent capture spring.
Also, ejection is like 1-2 o’clock which does not seem normal.

 

[AMP!]

FedEx just dropped off some 143 gr Hornady Precision Hunter. Went straight out and fired 3 rounds. They cycled, but did not lock back.

 

[davsco]

try using a lighter viscosity oil. and make sure any gunked oil is removed from receiver, buffer, etc.

 

[AMP!]

Any recommendations? I’ve been using the slip for awhile now. And it was just cleaned. I’ve been cleaning it every few rounds for barre break in. Did the whole BCG after the first 10, and the next 20.

 

[Stooxie]

EWL 2000 should be fine in cold weather. Grease would definitely be a problem.

Ejecting at 1pm is too fast, it is absolutely possible that the action is cycling too fast for the bolt catch to pop up and stop the bolt. Turn your gas down so that it's ejecting at 3pm to 4pm.

FYI, you should also totally expect to have to adjust the gas block for different ammo. There's a vast difference in gas pressure between Superformance (which isn't even recommended for gas guns) and regular target loads. One to three clicks is not uncommon. Doubly so with the use of a suppressor.

-Stooxie

 

[AMP!]

I thought too little was the issue. I guess I don’t fully understand the gas adjustments. I thought if it didn’t cycle or lock back, you should open the gas block more?

 

[308pirate]

I thought if it didn’t cycle or lock back, you should open the gas block more?

Read Stooxie's explanation again. It's very likely he's right.

 

[AMP!]

I cleaned up the BCG with a different mix of Cleaner/Lube. There was a slight buildup inside the bolt. Will adjust the GB down and test her out here in a few. Going to let the gun and ammo sit outside again to mimic yesterday.

 

[AMP!]

It’s about 18 F today. Adjust the GB down to where it would not eject. Open 1 click it would eject but not cycle, one more click and she cycles everything fine, but will not lock back. Opened it up two more, one at a time, still doesn’t lock back and is ejecting at 1-2 again. I turned it back down, everything cycles fine as before but the bolt never locks back.

JP SIlent capture spring suspect?

 

[davsco]

do you have an indoor range around to try it in warmer temps? at least eliminate the hot or cold variable.

i've been using wilson combat oil exclusively for years now with no issues (in everything, AR's, handguns...) but few weekends ago in the cold my 2011 was a little sluggish and had a few malfs for first time ever. after cleaning and before next match i used some benelli oil that is def lighter and had no problems the next match, also cold.

 

[The DFC]

To eliminate hot/cold variable just keep rifle warm in house or car until you shoot-although I don't think it takes long for it to get cold I would at least think at first you'd be somewhat warm.

Does this with multiple types of magazines?

 

[The DFC]

Also-I shot my LMT MWS with 6.5 cm barrel yesterday-20degF. Loading first round I noticed the bolt was ~2mm back from full battery. Just a little love tap and it went to full. After that all was normal with the following 50 rounds. I use Lucas gun oil.

 

[SupressYourself]

The lack of lock-back may be due to the magazine. I've had a few p-mags that would do that even though they didn't seem to look any different.
For gas adjustment, I would focus more on consistent cycling and ejection at 3-4 o'clock.

 

[The King]

If you go from underpasses to over in 2 clicks your operating system is heavily gassed. What bolt carrier? Which combination of JP scs weights? And are you using a rifle tube or a carbine tube?

 

[Greg Langelius *]

My guess is it's the magazine, everything else sounds like it's working right. Clean the mag internals completely and try it again. If no joy, try some graphite on the mag interior, the follower may be hanging up before reaching full height.

The same for the bolt catch; blow it out with Gun Scrubber, dry it, and leave it dry. No joy, graphite.

Finally, with only minimal rounds through it, there may be something going on that will be cured by simply shooting a bunch more rounds. A friend is going through this with a home build, and it's improving as the round count builds up. AR/Stoner actions accumulate carbon in places that don't always get completely cleaned, and that carbon sometimes behaves like graphite.

Greg

 

[Subwrx300]

If you go from underpasses to over in 2 clicks your operating system is heavily gassed. What bolt carrier? Which combination of JP scs weights? And are you using a rifle tube or a carbine tube?

This. I think you are seeing overgassed issue: it can mimic being undergassed. You likely need a heavier spring and then reduce gas. The JP tuner spring kit is well worth 30 bucks. It really helps dial in cycling issues.

 

[AMP!]

Thanks for all the info so far guys. This is my first large frame build. I’m using the standard JP SCS. No different springs or weights, in a rifle tube. And an Aero Nib BCG because they were on sale for $160.

I have not tried different mags. That should have been the first thing I did. I believe it was 3 clicks to overgas from cycling normally. But still not much wiggle room.

I don’t have an indoor range close by, but I can keep her warm and the test her within a minute of going outdoors. I keep a 100 yard range in the back yard. I will try a different mag and that tomorrow.

 

[The King]

I use the JP VMOS for this - their buffered bolt carrier. Helps keep everything in the awesome.

 

[AMP!]

I believe I found the sweet spot of the gas block. She is consistently cycling everything now. I made a video of some of the issues from the other day if anyone wants to check it out. I slowed down two of the shots so you can see it cycling towards the end. Also this was before I adjusted the gas block to get her where she is now.

Link to that video:

She cycles everything and ejects around 3-4 o'clock. One click down ejection is between 5-6 but it won't reliably feed. However, even with different mags she will not lock back. Would a heavier spring on the JP SCS help? If the springs are only $30, I may get another one of those ordered.

I'm currently making another vid of some shooting and groups. Helps to get this stuff on camera so I can see what is going on. Will keep you posted.

 

[AMP!]

Here are three 3 shot groups I just shot at 100.

 

[The King]

Does the bolt hold open freely move in its channel?

And can you easily lock it back by hand?

 

[Stooxie]

Just one more thing. I put a JP Silent Capture Spring in an AR308 and, while I like it, I found I had use the heaviest spring (that they include) and also switch out at least one of the weights to a tungsten one. The symptom was similar to what you describe where, each click of the gas block had too much "effect" on the gas system. I want to be able to use the gas block to fine tune, not go from 0-60 in three clicks.

I like JP stuff but much of it is geared towards the lightweight actions of 3 gun shooters. You just have to know which parts are which. If you're still looking to experiment, I bet using a plain old DPMS 308 carbine spring and buffer will make the system way less sensitive.

-Stooxie

 

[AMP!]

Does the bolt hold open freely move in its channel?

And can you easily lock it back by hand?

Yeah I can easily lock it back by hand. With or without a mag in just by pulling the CH.

 

[Stooxie]

I watched the video, you're definitely cycling too quickly. It was amusing to watch the cartridge casings hit the ammo box, like a split beam cannon from a video game. Those cases should be ideally thrown back and to the right (3 o'clock to 4 o'clock, give or take). When they are shooting forward and spinning around like a firecracker the action is cycling too quickly.

It also appears that your bolt doesn't travel back far enough, but that could just be the camera angle. The BCG should be able to travel far enough back to leave at least a quarter to a third of an inch between the front of the lugs and the bolt catch. The bolt should NEVER catch on the mag follower nor should the shoulder of the carrier catch on anything. You want at least one entire lug covered by the bolt catch when it's up. I've seen it where the bolt catch was undersized (either by using an AR15 one or via poor machining).

Also check the extractor tension on the BCG. Your first shot was a failure to extract, which could again be because the bolt is cycling too fast and the case had yet to shrink back down before the BCG started yanking on it. For now, just make sure that there is only ONE o-ring (or none) under the extractor. Also make sure the extractor has a well machined, well defined slot where it goes over the rim. Lousy extractors don't cleanly grab. Some companies use parkerized extractors even on nickel boron bolts because the extractor is not necessarily where you want "slick." But just make sure there is only one o-ring for now.

Lastly, take note of details like where your brass is flying, where your BCG ended up, did it fail to extract, eject or feed? Your video is very helpful to us, now we need to get it to be helpful for you!

What you want is a steady, smooth, full stroke of the BCG. Everything needs time to happen. The case needs time to shrink after firing so the extractor can pull it out, the BCG needs to travel far enough back so the case can be flung away and a new cartridge stripped off. It also needs to travel far enough back so that the mag spring pushes the bolt catch up before the BCG comes rushing back. Get it working with ONE kind of ammo before switching to something else.

-Stooxie

 

[The DFC]

I watched the video, you're definitely cycling too quickly. It was amusing to watch the cartridge casings hit the ammo box, like a split beam cannon from a video game. Those cases should be ideally thrown back and to the right (3 o'clock to 4 o'clock, give or take). When they are shooting forward and spinning around like a firecracker the action is cycling too quickly.

It also appears that your bolt doesn't travel back far enough, but that could just be the camera angle. The BCG should be able to travel far enough back to leave at least a quarter to a third of an inch between the front of the lugs and the mag catch. The bolt should NEVER catch on the mag follower nor should the shoulder of the carrier catch on anything. You want at least one entire lug covered by the bolt catch when it's up. I've seen it where the bolt catch was undersized (either by using an AR15 one or via poor machining).

Also check the extractor tension on the BCG. Your first shot was a failure to extract, which could again be because the bolt is cycling too fast and the case had yet to shrink back down before the BCG started yanking on it. For now, just make sure that there is only ONE o-ring (or none) under the extractor. Also make sure the extractor has a well machined, well defined slot where it goes over the rim. Lousy extractors don't cleanly grab. Some companies use parkerized extractors even on nickel boron bolts because the extractor is not necessarily where you want "slick." But just make sure there is only one o-ring for now.

Lastly, take note of details like where your brass is flying, where your BCG ended up, did it fail to extract, eject or feed? Your video is very helpful to us, now we need to get it to be helpful for you!

What you want is a steady, smooth, full stroke of the BCG. Everything needs time to happen. The case needs time to shrink after firing so the extractor can pull it out, the BCG needs to travel far enough back so the case can be flung away and a new cartridge stripped off. It also needs to travel far enough back so that the mag spring pushes the bolt catch up before the BCG comes rushing back. Get it working with ONE kind of ammo before switching to something else.

-Stooxie

A lot of good observavtions here-nothing to add other than it's a nice looking rig.

 

[DRAM40A1]

I have a POF that was giving me fits forever and I finally installed an XH Carbine buffer and Armalite rifle spring and it cleared up all my malfunctions.
I’d try a heavier buffer.

 

[AMP!]

Just FYI, I just built another one with my brother (walked him through the assembly) with the same BCG and JP Spring. Both 6.5 CM with rifle gas. Only difference is the barrels. Mine is a Ballistic Advantage, he went with Faxon. His rifle cycled, ejected, and locked back perfectly from the first shot. My BA barrel gas port may be out of spec.

 

[GrandpaDeadLegs]

Probably not your issue but in the Korean War they had to de-oil the carbines completely, and if they froze again, dudes pissed on them to get back to business

 

[AMP!]

Probably not your issue but in the Korean War they had to de-oil the carbines completely, and if they froze again, dudes pissed on them to get back to business

I'll remember this if I'm ever in a hairy situation.

 

[The DFC]

Have you tried peeing on it?

 

[chavezz556]

FedEx just dropped off some 143 gr Hornady Precision Hunter. Went straight out and fired 3 rounds. They cycled, but did not lock back.

I had this happen in my 224v using factory 88 grn eldm's... Chrono at 2520 fps.. I might as well shoot 223 with those #'s

 

[lash]

I had this happen in my 224v using factory 88 grn eldm's... Chrono at 2520 fps.. I might as well shoot 223 with those #'s

What barrel and length? I’m getting 2750 FPS with factory Hornady 88s in a 22” Rock Creek. I can see why 2520 would leave you less than impressed.

 

[AMP!]

Good news! She runs fine now with every ammo I feed her.



A little clip of my brother shooting his after I got mine dialed in. We took them out to 400 last week. Both holding MOA with factory ammo.

Thanks again for the tips. Didn’t even have to pee on it.

 

[The DFC]

Cool-love shooting long distance steel.

Did I miss the fix?

 

[AMP!]

Cool-love shooting long distance steel.

Did I miss the fix?

I think it was a combination of the thick oil, dirt, and being brand new. I cleaned her up and shot some more, had one more failure out of 20 rounds then she’s been running smooth. The bolt is moving way easier now.

My brothers did the same thing (same Aero BCG) a few times. Seems like they’re just really stiff from the factory.

 

[AMP!]

Another update, she’s been running like a champ and seems to like the Hornady Precision Hunter. 5 shot group from yesterday after I removed and painted the scope.

Not bad for a $1,600 build.

I repainted a kryptek style camo on it. Not sure if I like it or want to go back to FDE or OD, but here she is for now.

 

[The DFC]

Nice. Paint job looks great.

 

[SupressYourself]

That's badass, and as someone whos painted guns with Duracoat, I know how much work it is to spray an intricate pattern like that. The stencils are tedious. IMO, you'd be out of your mind to spray anything over that. I would probably spray the barrel in the darker brown color though.

 

[AMP!]

That's badass, and as someone whos painted guns with Duracoat, I know how much work it is to spray an intricate pattern like that. The stencils are tedious. IMO, you'd be out of your mind to spray anything over that. I would probably spray the barrel in the darker brown color though.

Yeah it’s at least a two day process for me. The barrel was bead blasted which I definitely didn’t like. The magpul FDE May look better on it than the black for sure though, and that’s simple job. Thanks for the tip, I may just do that.

 

[SupressYourself]

Are you using Duracoat, Cerekote, or something else?
I like the Duracoat Ultra flat colors on hunting rifles. The regular colors are too shiny. However, I've found that if you spray the base coat with the normal 12:1 paint to hardener ratio, and then spray a second coat with a 24:1 ratio (immediately after the first coat is fine), it still has a durable base coat, but is far less shiny -- although still not quite a flat as the "ultra flat" colors.

 

[AMP!]

Are you using Duracoat, Cerekote, or something else?
I like the Duracoat Ultra flat colors on hunting rifles. The regular colors are too shiny. However, I've found that if you spray the base coat with the normal 12:1 paint to hardener ratio, and then spray a second coat with a 24:1 ratio (immediately after the first coat is fine), it still has a durable base coat, but is far less shiny -- although still not quite a flat as the "ultra flat" colors.

Using Duracoat. And yeah, changing the ratio of the hardener can help make colors a little flatter. I haven't tried using their ultra flat colors. I usually do a few light layers and it turns out nicely. If I turn it up to a thicker layer there is definitely too much shine.

 

[AMP!]

Another vid of her up since I painted the scope. Looks like the DOPE changed a bit. Probably a combination of scope position and weather of course, but good stuff nonetheless.



BTW she has about 100 rounds through her now and runs super smooth. No further issues to speak of either. CHEERS!