Zumabob JD Machine Build

[zumabob1957]

I have a JD upper And lower, butt stock, buffer tube, & spring and a lower parts kit. I have some questions about ordering from Brownell's. 

Is a forward assist button for a 223 the same for a 308 ? Does the 308 dust cover come in a kit or does it come in 4 pieces ? I'm starting with the less expensive items for now putting off the pricey items for later. So far you all have been very helpful. Maybe I well be able to help the rookies when I become the old veteran on the block.

                       

[98Z5V]

Is a forward assist button for a 223 the same for a 308 ? Does the 308 dust cover come in a kit or does it come in 4 pieces ?                       

Forward assist is the same as the AR-15 parts.  Don't know if the dust cover comes as a kit from anybody, but anyone might have that, Fulton Armory might be the ones.

[zumabob1957]

Thank you for the info.

                Bob

[zumabob1957]

I have been searching high and low on the ar-10 & 15 sights . This is the first time I have seen Fulton Armory. What else am I missing ?

    Thank you again

f

[zumabob1957]

Anyone have a opinion on diopter drum rear sights made by Itac & Rainier ? I saw one @ the gun shop and it was outrageously expensive. It is about 220.00 but @ Amazon its as low as 90.00 which is reasonable. Just another obsession. Rainier is nice and about 105.00. Not quite beefy enough.

[zumabob1957]

I ordered a 16" barrel from Rainier  Arms . It was the only one that I could find with everything I wanted. 16", Mid length, .750 @ gas block and between 200.00 to 300.00.

  Anyone got any suggestions on handguards ? I like Troy but I dont know if I well work with my configuation. I would like to stay in the  200.00 range. I trying to build this 308 for under 2000.00. Im @ 1540.00 . Need hand guard and gas tube

[NoFail]

I ordered a 16" barrel from Rainier  Arms . It was the only one that I could find with everything I wanted. 16", Mid length, .750 @ gas block and between 200.00 to 300.00.

  Anyone got any suggestions on handguards ? I like Troy but I dont know if I well work with my configuation. I would like to stay in the  200.00 range. I trying to build this 308 for under 2000.00. Im @ 1540.00 . Need hand guard and gas tube

Why not get the JDM tube to go with your JDM set? I got the 14" it is $219. from JD Machine.

[zumabob1957]

I love all of JD Machine's products and we need to support a California manufactuer . But I'm going for the square look , round is  comfortable and there is more options. I got my barrel today. I measured between the end of the upper to end of the gas block and I got  9 1/4". So now I have less options . I have noticed on the mid length 9" the actual length is 9.25". I know there is a hand rail out there for me. Daniel Defense has one thats almost perfect but it 375.00

[NoFail]

Yeah I like DD too but the price turned me way off back when i was starting my list. I was just thinking maybe the JDM tube would mount up nice and easy with their own upper  <dontknow>, yeah I dunno yet because I don't have their upper yet, maybe next week it will come. LOL, I thought if I built it they would come  <lmao>

[zumabob1957]

I'm going to call Troy Industries tomorrow to see if they have what I'm looking for. Hopefully the TRX system could work. The  Glendale Gun Show is this weekend maybe I can find some answers or ideas. There is a booth that I have bought some AR308 stuff from, these two guys are very knowledgable. I. well let you know what I come up with

[zumabob1957]

Talked to my guy from Sacramento  he informed me that

Troy is not going to work with the HP upper. Looks like I'm going to bite the bullet and get the SAmson or the Daniel Defense. I justify it by not going over 2000.00. I'm at 1850.00. I may be ready to shoot by Sunday.                                     

Rainier Arms is great. I ordered my barrel on

Thursday night  and it was on my door step Monday afternoon. No tax and reasonable shipping costs. I ordered a Vltor light clamp from DMPS the cost was 32.00 . with tax and shipping it was almost 50.00. Live and learn.

[zumabob1957]

I just live

[98Z5V]

Have you contacted JD Machine yet, to see what their upper receiver threads are based off?  It's either DPMS or Armalite.  There are lots of rails out there for both types.

[NoFail]

I called JD today to confirm I need DPMS barrel nut wrench and indeed it is. Maybe that would make sense that the threads are DPMS also  <dontknow>  But they probably are.

[Yamadawg]

Zumabob,

If you ordered that Rainier Arms select barrel be aware you will not be able to shoot the lighter ammunition. like PMC 147 gr and so on, the kind you can buy affordably in bulk for 308 type ammo.

My buddy ordered one before I had the chance to because he got paid first. So it was professionally mounted on the reciever and we headed to the desert. NO BUENO!! Those bullets would not stabilize worth a daan. This is one of the reasons they offer a 30 money back guarantee so when people find out that there ammo wont shoot through it they can send it back as long as its within 30 days.

After that I did some research and tons of people got rid of the select barrels due to their 1x11 twist rate that wont stabilize 147 gr. So unless you plan on shooting nothing but Hornady 163 and above and at about a dollar or more a round send it back.

I purchased the Rainier Arms Match grade barrel with the 1x10 twist that will stabilize the "lower quality" ammunition as people would say. sorry for the news. but if you do some research you will see my friend wasnt the only one having the problem.

[zumabob1957]

Yamadawg,

Thanks for the info. Even if you are the bearer of bad news. I was also informed that if you use a low mass bolt carrier it can correct the problem. The Sacramento connection said that the gas tube on the 223 is the same on the 308. The same amount of gas pushing a larger bolt. A low mass bolt carrier can sometimes fix the problem.

Your information is helpful. I am going to test this barrel soon as possible. This is an example why this site is so helpful. If this barrel doesn't workout what do you suggest

[zumabob1957]

Yamadawg'

That do you thing of the low mass bolt carrier idea ?

[Yamadawg]

Well bob heres the thing you will save money on buying a 1x11 twist barrel but have you seen the price on a JP Enterprises low mass BCG? Its about 430. Vs a DPMS thats around 240 max from a reputable dealer.

Using a low mass bolt to aid in the adding of velocity of the bullet exiting the barrel just doesnt sound correct.

Now correct that the gas tube is the same diameter. But its like blowing a spit ball through a straw. 223 being a little kids lungs vs a 308 adult lungs. Theres going to be more pressure going faster and stronger out of the 308. I think that makes sense  <dontknow>

Ive tried to save a buck and cut corners, even buying some used parts like the BCG from my buddy so he can get the JP low mass bolt. I was beside myself when I saw the Rainier Select but for me I just didnt wanna take that chance. Especially since I will be modifying the barrel which will void the warranty.

Also FYI about the low mass BCG. The JP one you will not be able to use your forward assist in aid of making your rifle function. Now me being me, Im a big believer in the TAP, RACK, BANG method and its been ingrained in me through my training that whenever you realease the charging handle when loading or reloading always make a habit to hit the forward assist. And just not having that option to send the bolt the 1/16 of an inch that the FA does just doesnt sit well with me.

[zumabob1957]

Yamadawg,

Im going to the gun show tomorrow to pick up a quad rail a samson or daniel defense. Both about the same price. Its going together and we well see that happens. Im  also buying 163gr.

Thanks for the good tips and suggestions. I well let you know what happens

                                   

                                          Bob

[Andreas6.5AR]

Hello Guys,

I have a JD matched receiver set with a JP low mass bolt carrier group and enhanced bolt and while it doesn't have the gear like surface of a typical 223 bolt, I find that if is just a matter of the rotation of the bolt not completed (perhaps the last 1/4 inch or so (when I release the bolt slowly for example) the Fulton Armories forward assist button does in fact engage the bolt carrier and force it closed (though there is some effort involved). When I first received the assembly I thought there is no way the forward is going to do anything other than prevent gases coming back at me, so I was pleasantly surprised to find this.

My set up is a bit different in that it is 6.5m Creedmoor, but that is the 308 bolt system anyway. Also using a JP adjustable gas system which works great.

[NoFail]

Hello Guys,

I have a JD matched receiver set with a JP low mass bolt carrier group and enhanced bolt and while it doesn't have the gear like surface of a typical 223 bolt, I find that if is just a matter of the rotation of the bolt not completed (perhaps the last 1/4 inch or so (when I release the bolt slowly for example) the Fulton Armories forward assist button does in fact engage the bolt carrier and force it closed (though there is some effort involved). When I first received the assembly I thought there is no way the forward is going to do anything other than prevent gases coming back at me, so I was pleasantly surprised to find this.

My set up is a bit different in that it is 6.5m Creedmoor, but that is the 308 bolt system anyway. Also using a JP adjustable gas system which works great.

Hi Andreas,

So did you once say that after like 40 rounds you started having extract or mag swipe problems because of fouling, and you think it is because of the LMOS Bolt Carrier being lighter? I remember that and keep thinking it came from you. Anyway you are using the Tubbs flat wire spring. I dunno maybe someone can chime in here because I don't really know any better yet. I'm waiting to see what happens because, as you know already, I went the JP LMOS route. I think it's because of what I read from you before (a few weeks ago?) that I began to worry. But I went different than you with the Slash's CAR-10 buffer. I'm worried that my system won't extract &/or swipe next round from mag reliably. I wasn't thinking I will have to worry about the bolt going back to battery though, unless of course there is a extract or swipe problem. Andreas can you summarize again exactly what is going on in your case?

[NoFail]

Andreas yes i just found it, it was on my own build thread, LOL!!!

You said, "and man that was filthy after 60 rounds on the weekend. I seriously want to get an ultrasonic cleaner for cleaning these parts well between firings. I also started to notice that it wasn't cycling completely every time after about 40 rounds, more gas didn't really help. It was pretty wide open already. I think my Tubb flat wire spring may have more compression force than the usual springs (But with that Slipstream grease worked in it is pretty quiet and I like that)."

Now your saying the bolt wasn't rotating all the way, on the way back to battery you mean? Eh, or the other way during extraction, but it seems like you meant back to battery....

[Andreas6.5AR]

Hi there Brother (No Fail),

I did have some issues that day. I gave it a good cleaning again... the hot gases blow back into the bolt assembly and I didn't realize that at first, so be very careful about the lubricants you use and how much, had a bit too much of a lighter oil in there once and it burned and really coked the action badly and it got pretty stiff but still cycled without one failure for the 50 rounds I shot that day. This is a learning experience for me I am not an AR expert (yet  :) ) but I hope to be considered one one day. After a disassembling all but the ejector pin (special tooling required to get it back together) on the bolt assembly, a really good cleaning with Break Free CLP and a light bronze brushing... a light greasing and it is smooth as silk again.

I wouldn't worry if I were you, I really think you are going to be fine with your build. The components you have selected are top quality parts... I have no doubt it will run like a charm. Just keep it clean to prevent premature wear. I have 180 rounds down the pipe now no signs of any issues on the bolt. (Other than the slight bend in the firing pin retention pin.)

Also please remember I am shooting factory ammo designed for target bolt guns (read slow burning). I think this may contribute to more dirt going into my bolt assembly. When I start reloading I will move to a slightly quicker burning powder like those used in the 7.62 military rounds.

I would definitely follow the target masters break in protocol if you are getting a top quality barrel like a match barrel. I didn't at first but in short order I did... (clean the barrel after each of the first ten shots, then clean after groups of 3 for 5  to 10 groups then after groups of 5).... using the Otis cable type unit makes it a snap to do. and the CLP is also the recommended cleaning agent here.

[Andreas6.5AR]

Hello No Fail,

The going back to battery is a separate thing... when it cycles it does so just fine, it was just the first day when I didn't have the right Allen Key to adjust the gas and the one other day after about 40 rounds as indicated that I didn't get it coming back far enough to pick up a new round. Yesterday was another 50 rounds and no issues. (and one guy came over and asked if his wife could try it.... when I was packing up they came back again and he said she wants one...  :)  She said, "well my7 B'day  is in November, Christmas in December and Anniversary in January... maybe a combined occasion gift?" and looked sheepishly at her husband... I think I have had about 10 people take 3 shots each with it so far.)

The rifle appears to be running great now, but I will keep you posted.

The not going back into battery was something I noticed the first day we were out when the cases would eject but not enough gas to pick up another round. If I pulled to cock and let go... no problem it was loading just fine, it was when I was easing a couple of rounds in to see what would happen and it hung up out of battery (which it will without a round too if you gently ease the handle in... at least with my spring system and buffer system it does). if it has its inertia from full free spring travel I have never had an issue of out of battery... you have to force it to do that. I was habitually checking at first that it is in place and in my case the JP bolt carrier system and JD Machine extractor port line up perfectly so I can easily see if there is any problem. Now I just pop away without checking each round.

What seems to be happening too is that it is starting to loosen up a bit become freer or smoother in action so I think it will get better in time yet.

[NoFail]

Oh okay  <thumbsup>

yeah that's right you were still in break in too, that matters much!!! I think I am going to go get Slip 2000 for my lube. lots of guys give it high praise. I like the idea of using a synthetic, after all, petroleum breaks down especially under the stress of high temps. Some guys are using mobil 1 or royal purple. I might not have ever thought of that if I hadn't read it here 1st. But yeah, why not?

Andreas you are starting to make me feel better now  <thumbsup>