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not sure if the weight is the sole reason for the low cyclic rate, its definately a contributing factor but I wonder if its all thats going on here?

 

eg 325g bolt carrier run with stock AGM plastic buffer is 336 gram of weight thats having to be cycled, heavy yes ..but RAT carrier fitted to a rifle along with heavy weight buffer is around 305 to 310 grammes of weight and that combo can still turn out half decent ROF

 

 

 

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Does the bolt move smoothly in and out of the carrier? Perhaps under pressure the o-ring is expanding too much causing excessive friction during cycling. And improperly sized o-ring or ring gland could cause such a situation. If anybody had the bore diameter, o-ring size, bolt diameter, and gland dimensions I can do the calculations to determine if it is correctly designed, and if not, what size o-ring would be ideal.

Edited by t_hum
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couldnt tell you, still twiddling my thumbs waiting on mine to arrive.. Id also take a look at how restricted the blowback setup is as Ino run their own NP config (might be prompting similar condition to a RAT NPAS system thats been adjusted almost entirely to muzzle energy where recoil and ROF can go down the toilet)

 

if these are INO parts that have had the backside milled off them and dumped onto the market then things may not be optimal 'under the hood' I know there was talk of the Ino 2009 carrier group being revised prior to release, so solution then might be to do a direct compare with the Ino part that actually shipped with the 2009 MTW to see what (if any) alterations have been made.

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I dont think these are merely dumped INO carriers. I think JDT got ahold of leaked plans and made their own. Whether or not those plans were pre-release prints of final prints is the question.

 

Just my theory. Either way, Im sure with modification these can be made to work.

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Did some testing today, unfortunately indoors only.

Used two types of gas - Abbey predator ultra (which is utter *suitcase* when temperature lower beneath 15 C), and Green gas 22 (Red can with yellow stripes)

The abbey was ok in all of my mags but when I filled up the AGM mag with it, the hammer couldn't depress the valve. Damn - to strong gas. The GHK's cycled.

 

As I mentioned earlier, I had problems with my GHK's cooling down too rapidly. On the side note they also had the tendency to lock up and freeze the valve. The valve staid stuck even after an hour or two, or even a day... when it was not frozen anymore obviously.

I ordered the spare element spring and pin set (lucky buy), cut the mag catch spring which is perfectly dimensioned :D . I cut it in half and replaced with mag return valve – everything ok for now and the GHK mags work better. On the side note today my hammer pin broke. Indeed the element spring and pin set was a lucky buy.

img1372n.th.jpg

 

 

Mag catch isn't worn at all as seen in the pics, as not the bolt stop (this is before cleaning the inners :) ).

 

img1373z.th.jpg

 

img1375a.th.jpg

 

 

And I found how to successfully solve the BCG reliability problem!

 

img1377t.th.jpg

 

You really didn't think that I was really going to give you a decent solution to WA's troubles? :D

Got 4 of them, all AGM, some with element nozzles. Not happy at all with those elements. The plastic is cheap, the pins don't fit and the molding of the plastic is extremely crappy. AGM replacement is the way to go for now.

 

Also I got the 5ku charging handle. This is what is needed to get it fit:

 

img1381q.th.jpg

img1379s.th.jpg

 

 

 

Sorry for the lousy buy Luis, now you got your self almost a semi fire only weapon.

 

 

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got JDT steel trigger assembly and JDT firing block/boltcatch assembly in

 

 

steel trigger assembly - is a complete drop in unit you get trigger, trigger sear, trigger spring, trigger sear spring and a steel axis pin to hold it into the receiver with

 

the sear - same slab sided style as RAT and Ino - this one has the slightly squared off beak that an Ino one uses rather than the slightly rounded beak of an RAT sear

 

the trigger - I have two Ino triggers both are different

 

the one I got RAT to source me direct as an Ino spare part has slightly soft edges and the webbing behind the trigger blade met up with the trigger blade via an angled cut. That trigger has a slightly stippled/grainy finish and is very dark grey (pretty much a dead rigner for the 2008 trigger shown in Inos spare parts listing).

 

The other Ino trigger I bought later from airsoft global looks more like the current 2009 trigger - very squared edges the web behind the trigger blade mates up with the blade at far closer to a 90 degree angle (much less of an intermediate cut). Finish is smooth bar light machining marks and finished in near as damn jet black colour.

 

The JDT trigger is a dead ringer for the first of those two ie the 2008 style part.

 

 

JDT firing block/bolt catch assembly

As per trigger this is the complete preassembled unit - bolt catch (steel) the two halves of the block machined from alu, the firing pin (steel) the firing pin return spring, the bolt catch plunger and spring are G&P style where the plunger and spring act on stem of the bolt catch spring loading it (versus the original WA method of a little spring loaded detente that catches it near the top) Finish that off with the usual allen head bolt that holds the two halves of the block together.

 

 

Cosmetically its imperfect - someones taken one pass too many on the left hand section of the front face of the button, leaving a visible line where the surface steps down (it looks for all the world like a casting line but it isnt - if you look closely at it you can see the extra material thats been removed in that section is the cause - the line is just down to how the light is being reflected from the stepped surface that results).

 

Purely cosmetic doesnt affect the function (whiich is nice and clicky n positive against the spring and plunger)

 

Note this JDT firing block will need filed a little to fit into the AGM receiver

 

 

Conclusions

 

trigger assembly - if you've launched your existing trigger sear spring into oblivion and or want a trigger that will definately do the job this is the cheapest confirmed option. If you still have your trigger sear spring, dont mind a gamble consider the Element trigger and sear instead -you wont get the springs or axis pin and its untested as yet but is half the cost.

 

cons - none really (unless you hold the fact that the element might do same job against it)

 

 

Firing block needs a bit of filing will do the job.

 

Cons - costs 30 bucks or so whereas an RAT bolt catch is fifteen and an element steel hammer (which is supplied with a steel firign pin) is another 10, so for 25 bucks you'ld get same functionality and a steel hammer thrown in.

 

On plus side you dont need to take this block apart to fit steel firing pin - granted its an easy job, but some AGM firing blocks have the screw that holds them together torqued up waaay too tight (leaving you with a sheared bolt or stripped threads when you try to take it apart) and you get the revised G&P style spring and plunger on this block - which gives the bolt catch far more positive tension than AGMs slavish copy of the WA original.

 

Personally if money was really tight then Id treat myself to this block, and save cash on the trigger side of things.

Edited by snorkelman
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One thing to remember about the 5KU steel barrel set(5 pieces).

 

It has a thin barrel shoulder at the base where it mates with the upper receiver. The AGM barrel nut is made for barrels with thick shoulders, so there will be alot of leftover space and your barrel will wobble madly. If you don't want to get a new barrel nut then spacers will work. Just a heads up.

 

Other than that, you're good to go.

 

-Luis

I bought the 5KU barrel set from EBB and it came with a little bag of spacers as well.

I wonder if they've decided to stop giving them away or maybe you just didn't get them when you should have?

 

I just got my JDT BCG! I ordered it from PX-Airsoft.

 

All I can tell you about it right now is:

[...]

-Loading nozzle movement is very stiff inside carrier. O-Ring sticks too much....

 

Surely THIS is the main thing that needs sorting out before any conclusions can be drawn about performance?

 

:unsure:

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I bought the 5KU barrel set from EBB and it came with a little bag of spacers as well.

I wonder if they've decided to stop giving them away or maybe you just didn't get them when you should have?

 

 

 

Surely THIS is the main thing that needs sorting out before any conclusions can be drawn about performance?

 

:unsure:

 

Yes, I shaved down the O-Ring and the loading nozzle now moves freely. It's cycling good now.

 

I filmed the video for my 5KU mag performance and the JDT BCG review last night. I'll have them both uploaded by tommorrow.

 

Stay tuned.

 

Thanks,

 

-Luis

 

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Yeah, shaving down the o-ring not recommended. Your inbox is full Luis, btw.

 

I picked up a used AGM earlier this week as I need a test platform for a series of parts Im making. First on the list has been a CrMo bolt carrier and loading nozzle, both of which utilize a design which is a slight departure from the WA design. The more I look at the current bolt design I start to think that the major fault isn't necessarily weak materials (though they really are), but also the poor design of the bolt catch. Im starting to think that an improved bolt catch that engages the bolt differently is maybe more important.

 

What are your opinions?

Edited by t_hum
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After been readed the most of the post i´m going to make some changers on my AGM M4 GBB, but I wanted to know your opinion. Those are the internals I´m goint to use:

 

- 5KU Reinforced Spring & Pin Set

- G&P WA Hop Up Rubber

- G&P WA Steel Bolt Stop

- JDT WA GBB M4 6.03mm Stainless Steel Inner Barrel (368mm)

- Taiwan '' JDT '' WA GBB Hop Up Rubber & Aluminum Hop Up Chamber

- 5KU WA GBB M4 STEEL Outer Barrel

 

Then i´m going to install a NPAS because I need to downgrade the power to 350fps.

 

What more I need?

 

Thanks!

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I'm starting to think that an improved bolt catch that engages the bolt differently is maybe more important.

 

What are your opinions?

Definitely.

 

Be aware, however, that different magazines cause the bolt catch to operate differently.

 

The main thing that'd improve the way the bolt catch works would be to figure out a design that works more positively but, at the same time, is more sensitive.

Basically, if you can make it work from the AGM mag it should work with every other mag out there.

 

I guess a more substantial bolt catch might also be useful but, TBH, the BCG tends to sustain more damage than the catch usually.

 

It's kinda interesting but there's an accidental battle between parts going on all the time.

A company invents a reinforced BCG and then another company comes up with a steel bolt catch.

What we need to understand is that nothing is indestructable.

I'd rather that the $10 bolt-catch was sacrificed than a $100 BCG.

Perhaps what's needed is a hardened bolt catch with a small, soft, insert tha could be replaced when it becomes damaged?

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What I envision is a hardened BCG and a hardened catch seated in a steel firing block.

 

Or maybe the block needs a mechanism that keeps catch positively engaged or positively disengaged. The magazine activates the mechanism while the bolt release button just resets it.

 

One major flaw to the current design is the location of the axis for the bolt catch. It needs to be located closer to where the catch on a real AR is.

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well I finally got one of these carriers thru this morning so should have a chance to give it a thurough look over some stage this weekend

 

initial observations - very nicely made the machining and finish is on par with any other carrier out there and the finish on the nozzle tube puts the one on RATs 260 dollar carrier to shame.

 

this one had a sticker for m4gbb.com on it so that was either the wholesaler/retailer that the ones on sale in HK were sourced from, or the HK ones are a cancelled order from there.

 

yes it is heavy (315 on my digi scales in comparison to 241 for the RAT)

 

and yes theres certainly some weight that could be trimmed - the ID of the rear carrier section is 2mm less than the RAT part for starters leaving you with a carrier thats got 4mm thick wall rather than 3mm, the top cut is also Ino length not the longer WA/RAT length so theres a little more material can be taken off there

 

the carrier is steel

the side lock plate is steel

the gas key is steel

 

only the nozzle tube (gold bronzed anodized alu) and the NP valve arent steel (valve looks like brass on first glance) - even the Ino style bolt that fits inside the nozzle tube is steel going by a quick magnet test

 

wil fit and test fire it later - fit of the parts within the carrier is tight as a gnats chuff so I'd rather strip it check it n lube it up first

 

this carrier is 0.2mm wider OD than the AGM one (which makes it around 0.3mm OD wider than the RAT) so Id forget trying to use it on a JG (which already has a tendency to bind up running AGM carriers going by other folks reports?)

 

 

 

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After been readed the most of the post i´m going to make some changers on my AGM M4 GBB, but I wanted to know your opinion. Those are the internals I´m goint to use:

 

- 5KU Reinforced Spring & Pin Set

- G&P WA Hop Up Rubber

- G&P WA Steel Bolt Stop

- JDT WA GBB M4 6.03mm Stainless Steel Inner Barrel (368mm)

- Taiwan '' JDT '' WA GBB Hop Up Rubber & Aluminum Hop Up Chamber

- 5KU WA GBB M4 STEEL Outer Barrel

 

Then i´m going to install a NPAS because I need to downgrade the power to 350fps.

 

What more I need?

 

Thanks!

 

 

check prices before buying G&P bolt stop - you might find its expensive enough that you could buy an RAT bolt stop and RAT hop rubber for same price as the G&P bolt stop alone (even allowing for a few dollars postage to cover cost of RAT sending you those two parts seperate from parts you're ordering elsewhere)

 

the hop chamber in the EBB 'JDT hop rubber and aluminium hop chamber' is same hop chamber EBB sells on its own - if you're buying RAT rubber along with RAT bolt catch, then just buy the hop chamber on its own (dont bother with the extra few dollars to buy it with hop rubber)

 

things Id add would be fire control parts Element hammer element trigger element sear they're cheap and worth a try - you dont need to buy them straight away (and if you're sourcing them from EBbanned you wont save any postage including them in an existing order) but keep them in mind if your semi auto sear breaks etc

 

 

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one other area of extra weight on the ino carrier is the blowback chamber its 16mm ID rather than best part of 19mm for standard WA style carriers which adds another 1.5mm or so of wall thickness onto front half of the carrier that forms the blowback chamber too (another reason you're not going to be able to swap the Ino nozzle and bolt assembly out for a standard Wa/G&P/AGM/RAT etc one

 

Course that means not only do you have greater mass of bolt carrier you've got a blowback chamber with a lower capacity (same stroke narrower bore) and less of a surface for gas to expand against..

 

another ten grams of the difference is down to the nozzle assembly (54grams versus 44)

 

the bolt screws into the nozzle tube (no key and thru pin fit) and judging by this one has been thread locked in place as its just not for budging Im going to have to get some heat on it before I can reach the NP valve asembly ..tune in later once Ive turned myself into a human torch :)

 

one blowtorch later and Ive got the bolt n nozzle apart

 

1 it was loctited they've got red loctite over the threads like it was being spread on a strawberry jam sandwich

 

2 the unit comprises of a very fine spring, a brass flute valve, a brass castlated seat for that, a heavy duty spring that rests on in turn and finally a ledge insde the tube of the bolt for the heavy duty spring to sit against.

 

 

Edited by snorkelman
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