Q for those of you who build a mil-spec FSB T91 with .750 journal 14.5/16 barrel

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niqstr
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Tue Jul 14, 2020 9:04 pm

hi thx 4 confirming that 9-10inch is smaller[side view looked smaller vs 11-14mark which is prob 750]

i am hoping that the pinning will secure it to the smaller diameter around the 9-10inch mark?

otherwise i might have to get 416r ba wylde barrel w midlenght.

how much did it cost you and what is the official process called for getting rid of the shoulder?

thx u for your time in replying back..


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Prelude
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Thu Jul 16, 2020 11:11 pm

My suggestion is to add a set screw under the T91 gas block if you want to go the M4 barrel route. (Carbine gas system)
I did this to my 9mm T91, same issue there, the barrel OD is too small.
That way you can semi secure the gas block before pinning it.
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Otherwise it will not stay put.
I think it costs me almost $100 including shipping to get that barrel turn down. Labor is around $60.
It is costly, so later I tried to turn down the barrel myself, using router and wooden jig. They turn out well.
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niqstr
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Wed Jul 22, 2020 7:55 pm

wow yours look nice.

just bought the m4 barrel today.

so i will see how it goes. mail has been really slow. checking via tracking 4 t91 is almost annoying when u see "in transit" message 4 past week.

take care
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niqstr
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Wed Jul 22, 2020 7:59 pm

sorry but the t91 piston rod work[able to go through upper hole] in regular ie aero precision ar15 upper?
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Prelude
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Thu Jul 23, 2020 2:44 pm

niqstr wrote:
Wed Jul 22, 2020 7:59 pm
sorry but the t91 piston rod work[able to go through upper hole] in regular ie aero precision ar15 upper?
the T91 piston rod is slightly larger than gas tube
need to enlarge that hole a bit
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By the way, that upper was used to install the T91 Tactical 14.5" barrel.
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niqstr
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Fri Jul 24, 2020 6:55 pm

damn that sux. man didnt know it would be this much work...lol

that t91 looks sweet.

thx for your replies. hope i didnt bug you too much.
just great to be able to bounce ideas of someone who went
through the process.

also thx 4 the pix. they help visualize the process.

thx & have a great summer
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niqstr
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Sun Aug 09, 2020 6:44 pm

hi, got my m4 & t91 rod/gb. t91 gb slots up nice at 9inch mark but loose at 10inch.

was planning 2 use di bcg[as i had lying around 4 di build originally ] which would sync up at 10inch mark.
but someone mentioned that DI gas key [carpenter steel] will not survive 100rds. is that true/correct?

figured gas key 2 be more durable than that.


finally there is a "nut"/stud[on the right side] that secures the sling stud but mine slips off if i point it 2 the ground. is that ur
experience? or does yours secure? cuz the pin [1 of them] doesnt go into stud 2 secure it.
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Prelude
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Mon Aug 10, 2020 11:16 am

niqstr wrote:
Sun Aug 09, 2020 6:44 pm
hi, got my m4 & t91 rod/gb. t91 gb slots up nice at 9inch mark but loose at 10inch.

was planning 2 use di bcg[as i had lying around 4 di build originally ] which would sync up at 10inch mark.
but someone mentioned that DI gas key [carpenter steel] will not survive 100rds. is that true/correct?

figured gas key 2 be more durable than that.


finally there is a "nut"/stud[on the right side] that secures the sling stud but mine slips off if i point it 2 the ground. is that ur
experience? or does yours secure? cuz the pin [1 of them] doesnt go into stud 2 secure it.
Please don't use DI BCG for piston build. It is not designed to do so.
As for the T91 GB, you need to test install handguard to find the exact location where on the barrel the GB sits.
If the GB is somehow loosely around the location where it should be, I suggest you add some stainless shim to make it secured so you can continue to work on it (pinning it).
I don't follow the last part, are you talking about the sling attachment on the T91 GB?
it is loosen on mine.
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niqstr
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Tue Aug 11, 2020 8:08 pm

the sling is secured by an end piece[ie circular object ie stud in my parlance].on the right side of the gas block.

from sean you have to insert a pin to secure it. but i cant get the pin into the stud[which is the right side] of the sling pin.

? is how did you secure your sling that came w your gb?
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niqstr
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Fri Aug 14, 2020 7:15 pm

dont know who u are asking? but i sent to sean@t91 & still no reply on this.

the pin that holds the sling attachment is secured by a circular object located to the right side and sean showed a pic where the pin goes into the circular object. mine doesnt. and i dont want to use pliers to force it in unless that is what one has to get it in...

or is a defective pin...
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