Author Topic: DPMS GII, Recon model  (Read 576 times)

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Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #15 on: January 06, 2017, 11:10:04 AM »
Well, an update to the GII and it's "issues."

I'd ordered a YHM free float tube to replace that big old factory quadrail.  When it came in, the issues started.

Gas block set screws were glued in with a gray substance call rock set.  But they came loose without breaking the allen wrench or stripping the head out of the screws.

Quad rail was glued to the barrel nut with rock set.  Gouged it up some at the rear hammering on the big wrench used to tighten/loosen quadrails. 

The jamb nut for the quad rail was also glued to the barrel nut with rock set.  The wrench wouldn't budge it.  Finally got out a chisel and hammer and broke it loose, with some surface damage to the notch I set the chisel in.

I'd hoped to screw the new YHM free float tube onto the factory barrel nut but they have different threads.

The barrel nut came loose (no rock set, imagine that) but the barrel nut wrench broke up the little holes in the front that the pins of the wrench fit into .  Had to reposition the wrench several times to get now holes for the pins.  Did have to use a hammer on the wrench to break it loose though.

In order to get the barrel nut off the gas block had to come off.  In order to get the gas block off I'd have to take the flash suppressor off.  I couldn't budge the flash suppressor with the barrel clamped into a big bench vise wrapped in leather.  The big wrench mashed the flash suppressor flats some.

I ordered the AAC tool used to install/remove that style flash suppressor.  When it came in I clamped the barrel back in the vise and put the tool in my Snap On battery impact wrench and couldn't budge it.  I got the heat gun and put enough heat on the flash suppressor that the barrel 5" away was uncomfortably hot and the Snap On still wouldn't budge the flash suppressor.  I got the 1/2 air powered impact wrench and tried it and it would just slowly spin the barrel in the vise (leather wrapped barrel but it spun around enough to ring the barrel in the chamber area a little anyway.)

I ordered a barrel block for the vise.  It came in yesterday.  It has 3 different diameter holes in the two halve and they have rubber inserts to grip the barrel better.  I clamped the barrel and vise block into the vise and put a big wrench on the AAC tool.  No go.  I leaned on that thing and it turned in the vise block.  I cranked down some more on the vise till I was worrying about breaking the vise block and leaned on it some more.  No go.  I'm a big guy (6'3" and 300 lbs.)  I got a 3/8" drive ratchet, put it on the tool for the suppressor removal and put a big wrench on the back of the ratchet for more leverage.  When it popped loose (the suppressor) it made such a bang I first thought the barrel had broken at the threads.  I turned it some more and the flash suppressor turned loose and came off.  Sure enough.  DPMS had glued the flash suppressor to the barrel with rock set.

I was told that rock set could be loosened up by putting the parts down in a bucket/tub of water over night but I really hated to set my barrel/muzzle (even though it's stainless steel I didn't know if the flash suppressor was or not) in a bucket of water for 12 or 14 hours.  I've been told that rock set won't loosen up if you get caught outside in a heavy rainstorm for a few hours (water is water???)

Anyway, I finally had it where I wanted it.  I got the new barrel nut installed (easy), screwed the new YHM free float tube on (easy), got it lined up, tightened up the jamb nut, installed the set screws (all pretty easy), put the gas block back on and tightened up the set screws (easy) and put the flash suppressor back on (easy to do).

Only issue I have not is I need to remove a little more metal off the front/bottom of the scope mount so it doesn't contact the top rail on the free float tube.  I'd used the hobby belt sander (1" wide belt) to make one "cut" but didn't go back quite far enough.  I need the scope a bit farther forward to get my nose on the charging handle and get a clear image through the scope (no edge shadows).

I like those M16A1 butt stocks (a little shorter than the A2's) and I'd ordered a couple of those (have them on another rifle, too).  I'd also ordered a rifle buffer tube, buffer spring and buffer.  Found I couldn't use the rifle buffer due to the length of the GII bolt (would not go back far enough to allow the bolt to lock back on an empty magazine) so I took the rifle buffer out and put the GII buffer in it instead.  If you're going to use standard AR15 buffer tubes and stocks (like the GII does) the longer bolt requires a shorter buffer.

Here's the picture of the (almost) finished rifle.  Hopefully I'll get it to the range for yet another sight in session one day next week after the snow melts.  It should be gone by Wednesday or Thursday if it warms up like predicted.

And, nose to the charging handle on a .308?  So far I've put almost 200 rounds through it like that and while I can tell it's more recoil than a regular AR15 (.223/5.56X45) it's not as bad as you might think.

I might get around to camouflaging it some pretty day this spring when there's lots of sunshine to warm it up and dry it out.

I've got an adjustable gas block on order for it (back order it seems).  Without all the factory rock set that should be a much easier job.



Oh, this is what rock set looks like after you get the pieces apart.  The front ring on the barrel is about where the back of the flash suppressor stops/sits.  Not sure about the back ring though.  The barrel vise was set back at the shoulder where the gas block is usually located and is about 5" wide, so it didn't make those marks.

Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #16 on: January 19, 2017, 08:03:20 AM »
Well, thankfully a guy on arfcom recommended I check the use of a carbine buffer with the fixed stock tube (rifle buffer in a the rifle buffer tube will not allow the longer GII bolt carrier to move far enough into the buffer tube to feed rounds from the magazine or lock the bolt back on an empty magazine.)  I'd thought using a carbine buffer (like the original) might work but that's a definite no go unless I want the gas key striking the back of the receiver and eventually breaking something.

I've also got to cut the longer upper buttplate screw off where it sticks through the back of the buffer tube.  The A1 and A2 stocks use the same buffer tube, spring and buffer but the A2 stock, being longer, uses a plastic spacer between the tube and the butt plate so it uses a longer upper screw.  I've looked for A1 upper butt plate screws but have had to resort to using the longer A2 screw and cutting the tips off with a dremel cutting wheel.  That works and no one sees the end of the screw anyway.

Anyone here every shorten an AR15 rifle buffer?  It looks doable (from a first glance) by driving out the roll pin, removing the polymer bumper and cutting the tube on the back end.  I'd have to redrill the roll pin hole in the tube before reinstalling the polymer bumper and roll pin (after cutting the bugger to the right length to allow sufficient bolt carrier rearward movement without the carrier striking the back of the receiver).
Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #17 on: January 20, 2017, 12:41:01 PM »
Well, I think I've got a workable solution.

I ran across some H2 AR15 buffers in the parts cabinet (bought them a couple years ago and never had to use them).  I pulled one out and with the DPMS carbine buffer the rifle came with and a little sanding it looks workable.

I put the DPMS buffer in the buffer tube with the front to the back of the tube - so the spring would slide down over the tail of the buffer.  Then I put the H2 buffer on the front end of the spring and shoved the bolt/carrier into the tube.  No Go.  The length was a tad too long to allow the bolt to move far enough to the rear to lock the bolt back on the last round/empty magazine.

Both buffers had the polymer bumpers pinned to the rear.  I got out the hobby belt sander and took 3/8" off each polymer bumper pad.  I reinstalled the buffers and recoil spring and now have between 1/4" and 1/3" between the bolt face and the bolt catch with the bolt fully to the rear.  The clearance between the rear of the gas key and front of the lower receiver (where the buffer tube screws in) is more than enough to insure no contact.

Now, my Superlative Arms adjustable gas block should be in today or tomorrow (I hope, it left Butner, NC yesterday morning just after 830 AM - after all, how long can it take to get from Butner, NC to Chesterfield, VA - 3 hrs. for me in a car, but the is the US Mail we're talking about here).  I'll get it on and head to the range for a test shoot probably the middle of next week.

Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #18 on: January 22, 2017, 07:38:25 PM »
Sat down this afternoon to put the new adjustable gas block on the barrel.  Another mess.

Back to the garage to the vise/barrel block to get the flash suppressor off (no idea I'd hand tightened it that much).

The new free float tube and original gas block came off easily (no rock set used by me).

The problem came up when I drove the roll pin out of the factory gas block and could not (no way, no how) get the gas tube to come out of the gas block.  I pulled, I jerked, I smacked the gas block with the tack hammer and I finally gave up and dropped the gas block with the gas tube still stuck in it into a glass of water to soak overnight.  I'm thinking the sadistic rifle assembler at DPMS that put rock set on every thing threaded I've taken apart so far also put rock set in the gas block before driving the roll pin through the block/gas tube.

I was about to give up, sit down and order a new gas tube when I remembered I had a spare mid-length gas tube in the parts drawer in the garage.  SUCCESS!  I found it with no trouble (kind of uncommon).  I did some measuring (Mk1 eyeball) and test fitting.

The rear set screw on the adjustable gas block lined up perfectly with the indention in the barrel from the factory.  The front screw did not.  When I tightened down the front screw it left a mark and couple taps with a center punch and a drill bit with the 12 volt B&D cordless drill and I had an indention in the right spot for the new adjustable gas block. 

I again did some test fitting/looking and couldn't see the gas tube lining up the hole in the gas block.  Scared me.  Then I realized the adjustment shaft was fully closed.  I opened it up and I had alignment (checked with a bright light and my eye ball).  The I installed the gas tube and roll pin (nope, didn't use a bit of rock set since that's what the roll pin if for - hey, maybe the guys putting rifles together at DPMS don't know that's what roll pins and jam nuts are for???).

I slid the gas block on and checked for gas port alignment with a wire.  Had it.  I tightened the set screws on the gas port down, and installed the free float tube and hand tightened the flash suppressor (will take it to the vise/barrel block tomorrow when it's light outside). 

Now, maybe I can get to the range this coming week.  I've got a feeling I'm going to need a range trip to work off some frustration based on all the other stuff going on (wife's car in the garage 14 days now for a 3 to 4 day repair, 18 month old LG refrigerator repairs scheduled for Wednesday and I've got a bad feeling they're going to try to tell me the 10 year warranty on the compressor doesn't apply because.......).

Maybe I'll have a good range report to make all the aggravation worth it.
Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.

Offline copemech

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Re: DPMS GII, Recon model
« Reply #19 on: Today at 12:14:21 AM »
What a pain!

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #20 on: Today at 09:05:49 AM »
Saw thread on arfcom where a guy was asking about changing his flash suppressor on his GII Recon.  Two or three other posters replied that their suppressors were also stuck to the barrel with rock set.

Something to be aware of if you intend to buy a DPMS GII.  Apparently rock set is thought to be necessary by the people who put the rifles together.
Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.