Bolt catch spacing issue...

[firemanpete]

ok, Yes I'm new (just created an account today) yes I searched the forum for a thread regarding my issue, obviously didn't find my answer....so here we go.

I bought a Si-Defense upper from someone and also bought a DPMS LR308 lower from someone else(lower was already assembled, same w/ upper just minus a few parts) now my problem is this, they fit together fine, but the Bolt catch paddle (the upper part that has a relief cut for it on the upper) doesn't line up with the relief cut and the bolt will not pull back because the paddle is pushing the catch up and locking the bolt forward.  Obviously diff companies have different specs however, I have read in a few places that the DPMS lowers used a "screw" type thing instead of a standard roll pin because there's no way to tap a pin out if something on the catch breaks and needs to be replaced.  is that true? if it is, what size screw(or allen key) is it? I've tried a few standard and metric allen keys with no success.  can I just "shave down" perse the paddle to make it fit and not cause the catch to stick up making my rifle inoperable? Or do I just have to sell the SI-D upper and get a dpms one? my ultimate last resort option is dremelling the paddle part off and having a friend weld a piece onto it that sticks out more so as not to interfere with the upper.  I can get pictures to better explain/demonstrate my issue.  Any help is greatly appreciated.  ((and yes btw this is my first 308AR, figured I'd built enough 5.56 ones how much different can this be? lol obviously a lot)

 

-- Pete

[98Z5V]

Pete, pics will help greatly in this issue. Post pics of the fitment issue. I understand what you're saying, but you're going to get more solutions from others when the pics of the problem are posted.

 

Feel free to post up in the Intro Section, as well. 

[98Z5V]

In my opinion, machine the upper area that the bolt catch is hitting.  Cut it down.  There's plenty of meat there.

Edited July 4, 2017 by 98Z5V

[firemanpete]

6 minutes ago, 98Z5V said:

In my opinion, machine the upper area that the bolt catch is hitting.  Cut it down.  There's plenty of meat there.

just took a few pics and a video to show exactly what I mean.....give me a sec to get them from my phone to the computer and upload them... I don't think there's enough meat on the upper for that idea....

[98Z5V]

Dremel and this bit will solve it - before I even see the issue  - other ideas will come along shortly. 

[firemanpete]

video's being a bit of a bitch to get off my phone....need a min or so more for that lol

[firemanpete]

@98Z5V got the video to load.....hopefully you can see it.... what do you think?

IMG_4014.MOV

[survivalshop]

 Something is not right with that Upper Receiver , proprietary ?  SI Defense was bought out & no longer a business , I had one of their Gen II Uppers on a early CMMG Lower & everything lined up correctly .
 Could you photo the forward Pivot Pin area ?

  If you have the $$ , just purchase a DPMS type Upper or if there is enough material to have it Milled to extend the cut in it already , that can be done , but the only thing with that is , if this Upper is really made for something else or a goof , what could be next not to line up or is not with in spec's for a DPMS LR 308 Lower Receiver.

Edited July 4, 2017 by survivalshop

[98Z5V]

That's a left-over blem upper that someone had sitting in a back shelf somewhere.  Cut it.  It's not gonna hurt, because it's not worth anything else.  Extend that cutout in the upper, and it should work fine. 

If you can, get a wider pic that shows the upper and lower, with pin alignment - not necessarily pinned together, but apart - something to see the distance between front and rear pins, both upper and lower in the same pic.  It's definitely SI Defense, based on the cuts on the front of the shell deflector, but that square cut for the mag catch is something they did on the 5.56 guns, with the .308 guns having a round cut for it.  Somethings up.

Might as well chop it.  Seriously. It's not gonna hurt.

[98Z5V]

By the way, the vid came out great - but cutting the top off the bolt catch and welding something else to it isn't gonna solve that issue with the blem upper - that bolt catch recess in the upper is machined in the wrong place - it needs extended - for real. Everything else looks good, based on the vid, man.

That's a pretty fat bolt catch, too - but that's not the issue here.

Edited July 5, 2017 by 98Z5V

[firemanpete]

4 hours ago, 98Z5V said:

That's a left-over blem upper that someone had sitting in a back shelf somewhere.  Cut it.  It's not gonna hurt, because it's not worth anything else.  Extend that cutout in the upper, and it should work fine. 

If you can, get a wider pic that shows the upper and lower, with pin alignment - not necessarily pinned together, but apart - something to see the distance between front and rear pins, both upper and lower in the same pic.  It's definitely SI Defense, based on the cuts on the front of the shell deflector, but that square cut for the mag catch is something they did on the 5.56 guns, with the .308 guns having a round cut for it.  Somethings up.

Might as well chop it.  Seriously. It's not gonna hurt.

So you mean to tell me, the .308 BCG and barrel that fit perfectly are really in a 5.56 (based on the square cut) upper?! That's going to cause a problem if I try to use .308 than, which is what the ejection port is the size for.... Both my 5.56 bolt catch top paddle pieces are round though, so now I'm confused now LOL  regardless, the milling bit you showed a pic of, slapped into a dremel should mill out the relief on the upper yeah? Just making sure cause it doesn't look like there's enough meat there, hence why I wanted to shave the paddle on the bolt catch  

6 hours ago, survivalshop said:

 Something is not right with that Upper Receiver , proprietary ?  SI Defense was bought out & no longer a business , I had one of their Gen II Uppers on a early CMMG Lower & everything lined up correctly .
 Could you photo the forward Pivot Pin area ?

  If you have the $$ , just purchase a DPMS type Upper or if there is enough material to have it Milled to extend the cut in it already , that can be done , but the only thing with that is , if this Upper is really made for something else or a goof , what could be next not to line up or is not with in spec's for a DPMS LR 308 Lower Receiver.

I can get a pic of that yeah.... I'll do it after I get home frok the second job tomorrow evening.  

[98Z5V]

34 minutes ago, firemanpete said:

So you mean to tell me, the .308 BCG and barrel that fit perfectly are really in a 5.56 (based on the square cut) upper?!

No. That's not what I'm telling you.

You never would have gotten a 308 barrel into a 5.56 upper.

 

What I'm telling you is that upper wasn't machined in the "normal way" that SI Defense used to machine the 308 uppers. There's something up with it. The machining is all out of whack, and it's just not normal - it's not right.  They square-cut the 5.56 uppers in that area, they round-cut the 308 uppers in that area.  You have a 308 upper that has a 5.56 cut in it, IN THAT AREA.  That doesn't mean the whole upper is a 5.56 upper - which is why I asked you for pics of everything.  Bigass pics.  You ended up with a blem that probably shouldn't have left the machine shop.  It is what it is.

 

SO.  SO...

Cut it.

If the pins line up for the lower-to-upper mating, and the pins fit, then you have nothing to lose.  Cut the damn pocket for the bolt catch, and see if it functions.  If it doesn't - you're already out an non-functional upper receiver.  You don't have anything to lose here.

[firemanpete]

4 hours ago, 98Z5V said:

No. That's not what I'm telling you.

You never would have gotten a 308 barrel into a 5.56 upper.

 

What I'm telling you is that upper wasn't machined in the "normal way" that SI Defense used to machine the 308 uppers. There's something up with it. The machining is all out of whack, and it's just not normal - it's not right.  They square-cut the 5.56 uppers in that area, they round-cut the 308 uppers in that area.  You have a 308 upper that has a 5.56 cut in it, IN THAT AREA.  That doesn't mean the whole upper is a 5.56 upper - which is why I asked you for pics of everything.  Bigass pics.  You ended up with a blem that probably shouldn't have left the machine shop.  It is what it is.

 

SO.  SO...

Cut it.

If the pins line up for the lower-to-upper mating, and the pins fit, then you have nothing to lose.  Cut the damn pocket for the bolt catch, and see if it functions.  If it doesn't - you're already out an non-functional upper receiver.  You don't have anything to lose here.

Ooohhh ok, my apologies I misunderstood you.  Going to call my boy who has a dremmel tool and get that done. Thanks for the advice.   PS: sorry for sounding like a complete tool bag during this.... It's my first 308ar "build" perse  

 

@survivalshop here's a few pics I just took. (Woke up earlier than planned lol) it looks a little off but rifle's also laying on my bed lol.  I assure you the whole are all lined upand the pins fit and close. 

 

Edited July 5, 2017 by firemanpete

[survivalshop]

  Here is a photo of my Gen. II Upper on the CMMG  & no Chevrons on the Deflector , might have been something they did after the Gun.II  , which was an early Upper Receiver . Not to mention the side rail on the Receiver , which I never did find a use for . 
 Looks like the logo for SI Defense was changed also .

 

[firemanpete]

13 hours ago, survivalshop said:

  Here is a photo of my Gen. II Upper on the CMMG  & no Chevrons on the Deflector , might have been something they did after the Gun.II  , which was an early Upper Receiver . Not to mention the side rail on the Receiver , which I never did find a use for . 
 Looks like the logo for SI Defense was changed also .

 

Looks nice.  I see what y'all were saying about the round paddle... Just gotta figure out now if the paddle on my lower is a roll pin (makes no sense, since no way to remove roll pin if bolt catch breaks) or a "screw top" type, if that's the case what size is it designed for? Cause as I'm sure you saw in the pic aint a hell of a lot of meat to mill out from the upper to extend the relief cut for the paddle. 

[98Z5V]

I think all the DPMS LR308 lowers were set up for the screw, and not roll pin. I don't know the size of it offhand, but most of those screws (from DOMS, and other manufacturers) sucked, and broke if you even overtightened them a tiny bit.  Ironically, SI Defense made one from stainless, offered it separately, and people bought them up to replace their broken "other" screws.

The thing is basically a long allen set screw, that's been turned turn on the last 2/3rds of it.

Here's the DPMS one:

http://www.brownells.com/rifle-parts/bolt-parts/bolt-hardware/bolt-pins/dpms-bolt-catch-screw-prod54582.aspx

Here's one manufactured by Black Rain Ordinance, which I'd trust more than a DPMS one:

http://www.primaryarms.com/black-rain-ordnance-308-bolt-catch-screw-lr-12-308

 

This is what these things look like:

Find an allen wrench that fits it, and take it out. It'll be easy to find out what the thread pattern is.

[survivalshop]

 Makes me wonder if that Upper Receiver was made for a longer caliber , like a 300 win. mag.  or a 30'06 , because of its relationship to the  Bolt Stop . A longer caliber would bring the Mag Well back further & that would also move the Bolt Stop notch .

 

 Also not sure you have room to alter & keep the Upper Receivers integrity .

Edited July 6, 2017 by survivalshop

[98Z5V]

4 hours ago, survivalshop said:

 Makes me wonder if that Upper Receiver was made for a longer caliber , like a 300 win. mag.  or a 30'06 , because of its relationship to the  Bolt Stop . A longer caliber would bring the Mag Well back further & that would also move the Bolt Stop notch .

This is a great point -  time to start calling Falkor and trying to find background info.

The additional distance would be something close to this:

I poked around on Falkor's website, and can't find long action AR receivers.  Searching for SI DEfense long action AR receivers doesn't turn up anything, either.  Falkor does make a long action magazine for 300 Win Mag, though.

https://www.falkordefense.com/shop/parts-accessories/falkor-petra-10-round-magazine-300-win-mag/

 

[jtallen83]

They have a 300WM AR;

https://www.falkordefense.com/rifles/petra/

[Robocop1051]

These are both SI-D .308 rifles, built about 2 years apart. 

[firemanpete]

Thanks for all the info guys (and gals if it so applies) I gotta find me the right size allen key and see if I can't spin that bitch outta there LOL. then if I can, obviously get a bery thin head bolt catch paddle LOL. Or hell I just might have to get a new upper.... 

[survivalshop]

 Ya never know what SI Defense was experimenting with or what calibers .

[98Z5V]

5 hours ago, firemanpete said:

Thanks for all the info guys (and gals if it so applies) I gotta find me the right size allen key and see if I can't spin that bitch outta there LOL. then if I can, obviously get a bery thin head bolt catch paddle LOL. Or hell I just might have to get a new upper.... 

That's a THICK back on that bolt catch, for what it's worth.  That thing can take some shaving.

The more I look at it, the more I think that's a long action upper.  YOUR bolt catch recess on the upper is further back than normal - but so are the recesses in the upper for a magazine.  For a longer magazine?... 

That needs compared to a known 308ar upper, dimension-wise.  I'll measure as many as you need for reference info - I have DPMS, Aero Precision, and Matrix Aerospace to go from. 

How far back that magwell recess/cut in the upper extends readward, from the front pivot pin area... 

[98Z5V]

Nope.  That ain't it.Screw my last ass-essment.

Magwell length in the upper is 3.550" on a 308AR upper. For a .308 Win caliber upper, or any derivative.  Note closely how far back my 308 BCG is, back of the BCG body, firing pin location, etc.  Yours is the same, from your pics above. 

Your bolt catch cutout is on the wrong place, and that's not a long-action upper. 

The pic below is my Matrix upper. I think this posting-attemp will attach your pic first, then mine...

 

[firemanpete]

1 hour ago, 98Z5V said:

That's a THICK back on that bolt catch, for what it's worth.  That thing can take some shaving.... 

Lol, see that's what I was thinking originally as well.... Glad you're seeing it the same as I am LOL.  Going to see if I can't combo it... Ie: shave the bolt catch paddle a d bit and extend that relief cut a bit too.  Hopefully it won't blow up in my face, that would kind of suck, LOL  

1 hour ago, 98Z5V said:

The pic below is my Matrix upper. I think this posting-attemp will attach your pic first, then mine...

 

Yes I see what you mean.... I guess I got a blem upper... Eh I'm not worried... I'll make it work.  Thank you again for your help I do appreciate it.