Author Topic: DPMS GII, Recon model  (Read 1567 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: January 23, 2017, 12:14:21 AM »
What a pain!

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #20 on: January 23, 2017, 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.

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #21 on: February 10, 2017, 11:08:03 AM »
Well, shot it day before yesterday.  Again, it was 100% reliable, fed, chambered fired and extracted every round.

I started of trying to adjust the Superlative Arms adjustable gas block.  Followed the instructions until near the end.  I turned it shut, then open 4.5 turns to the "full open" position.  I loaded 1 round in the magazine, inserted the magazine and fired the round.  The bolt locked back.  Per the instructions I opened the adjustment screw up 1/2 turn and repeated the one round per magazine, fire it, if the bolt locks back, repeat, repeat, repeat till it stops locking the bolt back.

Well, I went through 20 rounds and it was still locking the bolt back.  Then I went to 1 full turn after each shot.  Finally I stopped for fear I'd have so few threads in the gas block that a shot would launch the adjustment screw down range.

I do believe the recoil was reducing.  I could not tell it after each shot, but it did "feel" like the recoil was less by the time I'd finished.  I sighted it in at 25 yds. (didn't do this while adjusting the gas block so I could concentrate on adjustment screw turns counting.  We wanted to shoot the rifles at 100 yds. but the 100 yd. range was pretty packed so we put the stuff in the car and left.

When I cleaned it yesterday I found the gas screw was adjusted out past the point where the pawl would catch/stop/hold the adjustment screw.  I thought for sure, while adjusting at the range, that I could feel the clicks (I was also watching the turns of the allen wrench).  I'm not sure, at this point if I stopped right at the end of the ability of the pawl to hold the screw adjustment and firing it during sighting in bumped it off that last notch or if I went to far. 

I turned the screw back in all the way and came out 12.5 clicks to make sure I had plenty of "notch" left on the screw for the pawl to engage.

I did notice, when I cleaned it, that it was much cleaner inside than my AR15's when I shoot a similar number of rounds.  There was no carbon burnt on the tail of the bolt.  The oil on most of the bolt was still pretty clean when I wiped it off with a white patch.  The firing pin had no carbon burnt on it.  At just over 30 rounds through an AR15 I'd have carbon burnt to the tail of the bolt and the firing pin (done it so many times).

Maybe, just maybe, moving the adjustment screw out past the full open position (to reduce recoil by venting some of the gas) might also keep it cleaner back in the bolt and upper receiver, too.  Yes, testing by folks on arfcom shows that adjusting the screw past full open (to vent gas) reduces velocity by 60 or 80 fps (if I remember their numbers correctly) but I'm not worried about less than 100 fps loss in muzzle velocity.  I'm interested in groups, not speed of the bullet.

As for recoil?  I'm shooting with my nose to the charging handle just like a .223 AR15 and it's not "getting my attention" so recoil's not bad with SA surplus.  I've got some other reloading to catch up on and then I'll work on some .308 loads for the GII.
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 #22 on: February 10, 2017, 11:15:07 AM »
One other thing, about using the A1 stock.

The A1 buffer and buffer spring wouldn't work due to the longer .308 bolt.

A carbine buffer wouldn't work due to the short length allowing the bolt to come too far back into the buffer tube and letting the gas key strike the back of the lower receiver.

I ended up using the GII recoil spring and two carbine buffers.  I used the (very) heavy GII carbine buffer up front and standard carbine buffer inserted into the buffer tube in reverse.  The face of the second carbine buffer is up against the back of the buffer tube and sort of acts as both a spacer and a recoil spring guide (not that it's necessary, but I needed some type of spacer that didn't compress the recoil spring and therefore change it's characteristics.)  The two buffers were a tad too long so I used the hobby belt sander to take some of the polymer bumper material off each buffer.  Together I have about the same amount of polymer as one stock carbine buffer would have.  The two polymer buffers would make contact if the bolt was driven back hard enough, but that shouldn't hurt anything.

I will, when I get around to it, modify the rifle buffer by shortening it, and then experiment with it and a standard rifle recoil spring.  Sooner or later, I promise.
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 #23 on: February 22, 2017, 06:13:33 PM »
Slow day, rain and all.  Worked on the buffer set up for the GII.  Now I need to get to the range again and see what effect this might have had on the adjustable gas block setting/rifle function.

When I put the M16A1 stock on it I found the original buffer was too short and the M16A1/rifle buffer was too long.

In order to shoot it (remember, short on patience here) I did a couple measuring/modding cycles.  I ended up with the factory carbine (?) GII buffer up front against the back of the bolt and an AR15 carbine buffer in the rear (small end forward, acting as a spring guide and stop for the GII buffer to keep the bolt gas key from striking the rear of the lower receiver and damaging it).  I used the belt sander to remove enough of the buffer bumper (those polymer things on the rear of the buffer) to give me enough bolt travel to allow the bolt catch to function properly.  So, when the buffers made contact, it was buffer bumper to buffer bumper (Wobbly - say that three times real fast).

The rifle worked 100% set up like this.

As I said, rain today, so I got to looking at cutting the rifle length buffer down to match the combined length of the two carbine buffers.

Measure, add, measure, check the math, cut the rifle buffer tube (used a tubing cutter, worked just fine, had to clean up the edges of the cut with an old file).  Put it all together and DARN!!! the bolt wouldn't go back far enough.

Yeah, I'd removed all the buffer bumpers, weights, roll pins, etc. from all three buffers (bought some new buffer bumpers and I installed them in the two carbine buffers I'd been using so they were good to go, again, as standard carbine buffers.)  I forgot to measure the darn buffer bumpers after removing them from the buffers.  That required some more measuring/math and another cut of the buffer with some clean up of the cut edge.

Put the rifle buffer together and put it in the rifle without the spring and checked rearward travel of the bolt - no bolt gas key contact.  Great!  Took it apart, put the spring in it, checked rearward travel again and had no gas key contact (didn't expect it) and the bolt goes back just about 3/8" past the bolt catch.  Should be good to go.  Will have to shoot it to be sure.  The rifle spring is longer and smaller diameter (wire diameter) than the GII spring, but works with rifle buffer.  The GII spring was a slightly smaller ID than the rifle spring and just didn't want to go up onto the back of the rifle buffer.

Picture of the pieces (except the modified rifle buffer because it's in the rifle).  You can see the two carbine buffers, the two sanded down original buffer bumpers (the long smaller OD part of the bumper sticking up is what goes into the buffer) and the bag of buffer bumpers I bought.  Got the bumpers for $1 each.  Since shipping was almost $9 I figured I'd buy 10 bumpers to make it "worth it."



Yes, if it works, I'll be happy with it and no more mods. planned.  Just some load development and trips to the range.
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 eastman

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Re: DPMS GII, Recon model
« Reply #24 on: February 22, 2017, 09:25:19 PM »
Man I really wanna build an AR :|

I'm thinking about doing that next year. The only design features I am set on are - heavy barrel (20" or more), flat top with low gas block and a Rock River 2-stage match trigger. I plan to put a good scope on it and use it for 100 yard (or more) targets.

Best laid plans, and all ...

The 20" heavy barrel part was correct, but everything else changed (not building now, found a LN Colt HBAR). Need to remove the carry handle (with the rear sight) and replace it with an appropriate optic (Vortex, Nikon or Leupold all have potential options).
I don't look like my avatar!

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #25 on: February 24, 2017, 04:44:58 PM »
Picture of the shortened rifle AR15 rifle buffer.  I reused the original rifle buffer bumper.



The coolest thing of the day (spend part of the day replacing the AC and serpentine belts on the truck  - not too bad really - and replacing the evaporative emissions system vent valve solenoid - that was the pain in the butt) was at the end of the day when I remembered to get the buffer back out of the GII and go drill the new hole for the roll pin that holds the buffer bumper in the back end of the buffer.

I took it to the garage, plugged in the drill press, picked out the right sized drill bit (used the Mk1 eyeball for comparison of pin to bit diameter) and started lining up the buffer on the drill press "table".  Started to hold it, with my left hand off to the left side of the table.  Then it hit me it could be hard to center up the drill on the top of the buffer that way.  I turned the buffer so it was pointing directly away from my chest, with my left had against my chest and centered it up under the drill bit on a flat piece of wood.  I hit the "ON" button (drill bit turning at a very slow speed) and slowly pulled the handle to make the bit contact the buffer and start drilling the hole. 

As the bit turned some metal pieces were twisting off the surface of the buffer and then suddenly the bit went through the buffer and dropped like a rock through the polymer bumper.  Shook me up.  I was expecting a little resistance from the polymer bumper and some shavings.  Then it hit me - I'd (totally by luck/accident) hit the original hole in the polymer bumper.  I put more pressure on the drill bit with the handle and ran the bit through the other side of the buffer.  I shut off the drill press and took a look at it.  I wasn't exactly in the original hole as I could see a sliver of polymer in the edge of the newly drilled hole in the buffer.  But so close you couldn't tell otherwise.  I drove the old roll pin back in and brought it inside to take a picture and show my wife.  Luck.  Sometimes it happens.

That faint light line through the center of the buffer is the hole with the roll pin in it.  I couldn't do that again if I tried.

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 Swamp ash

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Re: DPMS GII, Recon model
« Reply #26 on: February 24, 2017, 10:46:14 PM »
This is a great thread! 

Have you seen the new Savage MSR line?
https://www.savagearms.com/firearms/model/msr10hunter
Ruger rimfire fan

Offline M1A4ME

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Re: DPMS GII, Recon model
« Reply #27 on: February 25, 2017, 07:07:06 AM »
Just saw an add yesterday for them.   Looks interesting, too.
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 Swamp ash

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Re: DPMS GII, Recon model
« Reply #28 on: February 27, 2017, 12:08:50 PM »
Just saw an add yesterday for them.   Looks interesting, too.
Yes, they look quite nice!  I have always had a fondness for Savage. 
Ruger rimfire fan

Offline Austin316

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Re: DPMS GII, Recon model
« Reply #29 on: March 04, 2017, 10:04:05 PM »
Midwest Industries has specific handguards for the GII including some 15" options.

https://www.midwestindustriesinc.com/category-s/313.htm

 

anything