View Full Version : Colt 10.3 FSP Question
I am down the rabbit hole on my 10.5 SBR build when it comes to the barrel. I will spare everyone the details but one of the options I came across was a 10.3 Colt surplus barrel with the FSP. It is a cut down 14.5 model. Price is decent so I am seriously considering it (even if I do have to open up the port a bit to get it to cycle a wider range of ammo.) It is most definitely going to have a dedicated can. My one fear is with thread concentricity not knowing who did the chop. Anyone have any feedback/experience on this topic?
I am down the rabbit hole on my 10.5 SBR build when it comes to the barrel. I will spare everyone the details but one of the options I came across was a 10.3 Colt surplus barrel with the FSP. It is a cut down 14.5 model. Price is decent so I am seriously considering it (even if I do have to open up the port a bit to get it to cycle a wider range of ammo.) It is most definitely going to have a dedicated can. My one fear is with thread concentricity not knowing who did the chop. Anyone have any feedback/experience on this topic?
If it's real surplus it was most likely cut down by Crane, it would probable be an early one with that FSB, although anythings possible in the supply chain.
If it's real surplus it was most likely cut down by Crane, it would probable be an early one with that FSB, although anythings possible in the supply chain.
They have manufacture dates from 2001 - 2010. Not sure which year (if any?) are better / worse? If Crane did the cut I am going to assume it's ok and take a flyer. I have an email into the vendor asking as well as if the FSP is F marked or not. I would really like to do a CL barrel for this build.
They have manufacture dates from 2001 - 2010. Not sure which year (if any?) are better / worse? If Crane did the cut I am going to assume it's ok and take a flyer. I have an email into the vendor asking as well as if the FSP is F marked or not. I would really like to do a CL barrel for this build.
Where are you seeing a vendor selling 10.3" legit surplus barrels? If you really felt like you wanted 10.3 over better offerings (making clones or whatever is still great don't get me wrong), I would be suspect over the barrels actually being valid mil surplus.
Where are you seeing a vendor selling 10.3" legit surplus barrels? If you really felt like you wanted 10.3 over better offerings (making clones or whatever is still great don't get me wrong), I would be suspect over the barrels actually being valid mil surplus.
I already have the better barrel lengths. This is because I want to see just how much gas I can take to the face while shooting suppressed. Figure I'll put on a YHM Turbo K and try out my WW2 surplus gas mask and see if the charcoal canisters still work :D
In all seriousness it's just another project I want to take on and play around with. I'll DM you the vendor. Don't want to get in trouble posting sales links in here to non site sponsors
Any reason to not just buy a Factory new LMT or Colt 10.3 or 10.5? I have gone that route with good success.
PB
Any reason to not just buy a Factory new LMT or Colt 10.3 or 10.5? I have gone that route with good success.
PB
Besides me being cheap? None. The surplus one I am looking at is 100 bucks plus cheaper. That and I am going to pull the FSB and open the port up to something between .072 and .075 and would hate to butcher a new barrel with my ham fisted wrenching.
Sounds like a great barrel to play with, if it was really used, you might not have to open the port at all. If it looks good, I'd shoot it first with that "wider range" of ammo and see how ya like it.
Sounds like a great barrel to play with, if it was really used, you might not have to open the port at all. If it looks good, I'd shoot it first with that "wider range" of ammo and see how ya like it.
You're probably right. I was going to open it up nominally to .072 and leave it alone since I need to take the handguard end cap off anyway (yeah I know I can cut it off but two birds, one stone.) But may just take your advice and shoot it a bunch first with and without the can and see how it behaves. IE do the smart thing :D
You're probably right. I was going to open it up nominally to .072 and leave it alone since I need to take the handguard end cap off anyway (yeah I know I can cut it off but two birds, one stone.) But may just take your advice and shoot it a bunch first with and without the can and see how it behaves. IE do the smart thing :D
How much is the unknown barrel? It might be cool if it all works out, but if it doesn't you have waisted every dime, not just the $100 plus you mention. Best of luck either way Dutch.
PB
How much is the unknown barrel? It might be cool if it all works out, but if it doesn't you have waisted every dime, not just the $100 plus you mention. Best of luck either way Dutch.
PB
Thanks PB. It ended up being 200 shipped so I took a flyer. Seller has A,B and C grade with him saying A and B are "excellent condition" and C being "Historical grade but functional." I opted for A. I'll either be a hero or a goat. I'll report back once I have it in hand.
I could be wrong, but I thought all the "legit" surplus cut downs dried up years ago.
If it's right it doesn't matter who cut it. If it's wrong well...
Thanks PB. It ended up being 200 shipped so I took a flyer. Seller has A,B and C grade with him saying A and B are "excellent condition" and C being "Historical grade but functional." I opted for A. I'll either be a hero or a goat. I'll report back once I have it in hand.
If you need to chock it down you could use BRT tubes and maybe not do any damage, if your familiar with those tubes. Hopefully it runs as is.
PB
If you need to chock it down you could use BRT tubes and maybe not do any damage, if your familiar with those tubes. Hopefully it runs as is.
PB
I've never run them but have heard good things on here.
For a dedicated suppressed cut down build, you dont want to touch the gas port at all.
It may be setup nicely unless the vendor already opened up the port.
While the FSB is pulled off, pin gage the port to be sure and go from there.
If the port is larger than factory, you'll want to do something to reduce the gas drive.
I am down the rabbit hole on my 10.5 SBR build when it comes to the barrel. I will spare everyone the details but one of the options I came across was a 10.3 Colt surplus barrel with the FSP. It is a cut down 14.5 model. Price is decent so I am seriously considering it (even if I do have to open up the port a bit to get it to cycle a wider range of ammo.) It is most definitely going to have a dedicated can. My one fear is with thread concentricity not knowing who did the chop. Anyone have any feedback/experience on this topic?
These are cut down Colt 14.5" with dates of manf. 2005-2010 grade A.
https://www.littlebyrdprocurement.com/product-page/colt-10-3-goverment-profile-with-fsp
These are cut down Colt 14.5" with dates of manf. 2005-2010 grade A.
https://www.littlebyrdprocurement.com/product-page/colt-10-3-goverment-profile-with-fsp
Yup. That's where I got this one from. Until I was sure it was legit I didn't want to promo it on here.
For a dedicated suppressed cut down build, you dont want to touch the gas port at all.
It may be setup nicely unless the vendor already opened up the port.
While the FSB is pulled off, pin gage the port to be sure and go from there.
If the port is larger than factory, you'll want to do something to reduce the gas drive.
Thanks Clint. Was on your site last night. I am going to gauge the hole and then go from there. Not sure which can is going on this yet. I have an Otter Creek Polonium that just came in but I kind of want to put a K can on this one. Once I get all that data I'll most likely get one of your gas tubes.
These have the port already opened up to 070, so too large for dedicated suppressed.
These are cut down Colt 14.5" with dates of manf. 2005-2010 grade A.
https://www.littlebyrdprocurement.com/product-page/colt-10-3-goverment-profile-with-fsp
These have the port already opened up to 070, so too large for dedicated suppressed.
Far be it from me to question the guy who makes a living giving people proper gas levels, but .070 is too large for dedicated suppressed out of a 10.3? I thought the original MK18's were in the .083 range (and very gassy.) Everything I have read says conventional wisdom is to keep it in the .073 ish range for being able to run a variety of ammo. The SOLGW boys use .073 and people complain about their barrels being gassy with a can. Like I said, I defer to your knowledge on this topic it just surprises me because all this time I have been told .070 may actually be too small.
What size would you use?
Me? I am going to run it as it shipped, see how it goes, and adjust from there. I'm not experienced with this set up at all so wouldn't pretend to give anyone advice. There is a ton of different opinions on the topic it seems. I did a quick perusal of published specs for port size on the 10.3 - 10.5 FSP barrels
Aero / BA - .0785
SOLGW - .073
LMT - .071 (I think I am going from memory here)
Colt - .070
TDP - .070
Daniel Defense - .070 now but from threads on here they originally shipped with .083 and were a tad on the gassy and bouncy side as a result.
I'm also going to be running a can. Which is also going to play into this. Which is why I am going to run it and go from there and adjust as needed.
Seriously tempted.
Mine shipped today and is showing up Friday. If you can hang on I'll let you know how it looks.
The Crane spec of 070 is just large enough to reliably run 556 ammo un-suppressed.
That 070 spec size will also function acceptably with most suppressors, but is quite a bit over driven and gassy.
it is hardly the right size for dedicated suppressed use.
The Crane spec of 070 is just large enough to reliably run 556 ammo un-suppressed.
That 070 spec size will also function acceptably with most suppressors, but is quite a bit over driven and gassy.
it is hardly the right size for dedicated suppressed use.
Thanks Clint. Appreciate it. In a perfect world what do you think is the correct port size for that application?
The correct gas port size depends on many factors, including the back pressure of the particular supressor model, but most fall just under 060.
That .010" drop from 070 to 060 is a BIG deal and represents a 26% reduction in flow area.
Thanks Clint. Appreciate it. In a perfect world what do you think is the correct port size for that application?
Finally got this all put together and to the range over the weekend to shoot it with and without the can (Otter Creek Polonium)
1. When I got the barrel in I swabbed the chamber and it came out clean. Ran a few patches down the bore as well and that came out clean too. Visual inspection saw no fouling or port erosion. I don't think this barrel had been shot much, if at all.
2. Got to the range and shot it without the can to get it on paper. Indoor range (can is still in jail so I was limited to indoors at 25 yards for my conjugal visit so keep that in mind)
3. First 60 - 100 rounds groups tightened up as expected with a new(ish) barrel.
4. Running an A5 with Sprinco green and an A5H2 buffer. Recoil impulse was good and ejection pattern was right around 3:00. It was a lot softer than I thought it would be to be honest.
5. Put the can on and ran another 100 rounds through it. Groups continued to get smaller. I was actually surprised by the lack of gas to the face. Using a Radian CH so no gas diversion. This same can on other rifles is a bit gassy so I was expecting this to be the same if not more so.
Conclusion? 200 rounds or so is by no means a thorough evaluation but initial impressions are that my sample size of one barrel from this lot is pretty darn good. Maybe I got lucky and got one that sat on the armorers shelf? With the can and an RDS and after breaking it in a bit it was consistently .5 to .75 at 25. So probably a 2 to 3 inch gun at 100? Which for a 10.5 milsurp barrel I am fine with. On and was shooting 55 grain Igman .223.
Oh my. From the same place I got my barrel.
https://www.littlebyrdprocurement.com/product-page/colt-mk18-mod-0-urg
Oh my. From the same place I got my barrel.
https://www.littlebyrdprocurement.com/product-page/colt-mk18-mod-0-urg
GB had some 6933 uppers for around $600 when I looked the other day. With BCG & CH. I got a KAC knock off rail so I was nosing around.
PB
GB had some 6933 uppers for around $600 when I looked the other day. With BCG & CH. I got a KAC knock off rail so I was nosing around.
PB
I saw that thread on the rails. They looked promising. 600 bucks is cheap!
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