Topic: DPMS 308 SASS Barrel and Gas Block Issue (Read 5001 times)

imschur · « **on:** October 17, 2010, 11:59:49 AM »

Alright, I decided to get to the bottom of this once and for all.

Here's a DPMS forum link and a Snipers Hide link describing the issue.

Lets talk about it

imschur · « **Reply #1 on:** October 17, 2010, 12:24:52 PM »

Now here is two images of whats supposed to be a PRI .936 and the SASS gas block. The SASS wall appears thicker which based on appearance would orient the gas tube higher.

Do you guys see it the same way?

Also I wonder if this also ties in to the new height of the upper receivers?

survivalshop · « **Reply #2 on:** October 18, 2010, 08:21:22 AM »

They is no alteration to the gas tube passage in the upper ,just the rail height difference .
For them to change the gas tube passage in the upper , you would have to also change or alter the carrier key.
Any thing that DPMS does now would not surprise me .
I am concerned with ,if they raised the gas tube height for it to fit into a higher then normal gas block to clear a higher than normal barrel , what kind of angle does the gas tube have going into the upper.
Are they being bent to keep it aliened with the key? (that's if they didn't alter the normal spec's on the gas tube passage in the upper & carrier key)
Or are they doing this just to keep there stuff ,there stuff .
Another idea could be a piston system coming ? Conversions any one ?

imschur · « **Reply #3 on:** October 18, 2010, 08:08:11 PM »

Well not that long ago they said they had zero interest in a piston gun. I'll they are trying to get more parts proprietary.

98Z5V · « **Reply #4 on:** October 19, 2010, 04:07:24 AM »

Here's what I'm thinking:

The shoulder on the barrel us huge. Even if the gas block mounting area is .936, the step is pretty big. Does a "standard" .936 gas block have the gas tube hole covered partially by that big step? If so, that would explain why the DPMS-specific block has a larger wall thickness - both to get the gas tube up high enough to clear the step, and for asthetics (O.D. as large as the fluted portion of the barrel).

SASS gas block:

If the above is true, then it also requires a special gas tube with a different bend - like ss said up there, I'm betting they didn't go to the R&D trouble to relocate the hole in the upper, and change the gas key. However, also like ss said, anything they do know would come as no surprise at all.

motorwerks · « **Reply #5 on:** October 24, 2010, 02:36:05 PM »

I would bet you could just bent the gas tube by hand if it didn't match up. Its only a 1/16th or so.

imschur · « **Reply #6 on:** October 24, 2010, 09:27:37 PM »

Does anyone have a .936 gas block I can borrow for photographic purposes to illustrate the issue?

DocLarsen · « **Reply #7 on:** November 01, 2010, 08:22:31 AM »

I am very interested in the outcome of this discussion; I am sitting on the fence trying to decide between a 18" SASS and a 24" fluted barrel. Has anyone come to actual bottom of this issue? If so, I'd really like to know!

DocLarsen

imschur · « **Reply #8 on:** November 01, 2010, 08:28:51 AM »

Without a doubt the barrel requires the DPMS proprietary gas block.

98Z5V · « **Reply #9 on:** November 01, 2010, 08:42:07 AM »

Is that because of the mounting height of the gas tube, at the gas block? Wall thickness of that DPMS SASS block, height-over-bore of the gas tube hole, which is higher than anything else with a .936 block...

Which will also mean you need the DPMS SASS-specific gas tube with a different bend in it...

I'm wondering if you can trench that barrel towards the shoulder, to accomodate a "standard" gas tube bend and "standard" .936 gas block? The gas tube would actually go down into the trenching, and right into the regular .936 gas block hole.

All the crazy stuff I've seen on the 'net is about a "tapered" gas block - which would be a huge problem if you planned on fitting a "standard" .936 block. If it's just offset due to DPMS' idiotic proprietary thinking and movement, then that can be overcome with machining tools...

98Z5V · « **Reply #10 on:** November 01, 2010, 08:54:02 AM »

Drew, here's a YHM .936 lo-pro gas block, some kind of DPMS lo-pro .936 block, and a PRI .936 lo-pro block - I used the PRI on my .308 build, onto the Fulton SS barrel.

Just from pics, I'd say focus on gas tube centerline over barrel centerline, just for the comparison. Best I can do from pics, brother...

imschur · « **Reply #11 on:** November 01, 2010, 10:11:45 AM »

Im going to buy the DPMS block this week. I would like to get a standard .936 block in hand to compare and publish the data with pictures

survivalshop · « **Reply #12 on:** November 03, 2010, 07:40:16 AM »

Just by looks , it appears the gas tube hole in the sass gas block is twice as high as std . gas holes in std .936 blocks.
That would mean the gas tube would be of a different configuration compared to a std gas tube.
Reconfiguring a gas tube is not a big deal. They wanted a specific barrel configuration and made a different gas block & reconfigured ( bent ) a gas tube .
The only thing here that is really of importance is the gas block change to make the gas tube come out higher to clear the barrel.

That is unless the barrel extension flange is also higher than std. , then you would need some reconfiguring of the upper receiver gas tube opening (higher ) , which I don't think they did , because people are building with the newer rail height with no problems .

They could have a special gas tube made up for that configuration also.
Its just S/S tubing & you can bend them any way you want , with some restrictions of course.

imschur · « **Reply #13 on:** November 03, 2010, 07:54:29 AM »

Long, thin and flexible, Ill bet the standard gas tube works without much issue. I checked the DPMS parts pages and there isnt a special tube listed.

Cash permitting Im hoping to get a Fulton stripped upper by Xmas and put this all to rest.

DocLarsen · « **Reply #14 on:** November 03, 2010, 08:23:37 AM »

I just pulled the trigger on a 18" SASS barrel and SASS Gas Block and the new SASS handguard. I am just shickled titless

and can't wait for it to arrive!! Should get here Friday or Saturday, Monday at the latest. I just couldn't see hasseling with something else; I had saved enough $$ in other places so that the $90 from JSE for the SASS gas block was doable and, with the new DPMS handguard, I'll have plenty of rail for my purposes.

I'll be starting a build thread soon LOL

I went to the local gun shop/FFL yesterday and got to play with a couple of their ARs and have been bouncing around like a school girl ever since; couldn't wait to put my order in this morning.

DocLarsen