M*CARBO Brotherhood

Heads-Up: Problem with KT Heavyweight (Brass) Bolt & Midwest Optic Mount

Reader’s Digest version: Looks like the combination of the KelTec brass heavyweight bolt and the Midwest Industries optic mount (specifically, the need to keep the bolt open while the sub is folded and wrestle the retention cord around the charging handle when folded) may have deformed the charging handle hole enough to prevent the bolt from coming out of the tube. Pics attached.

I have 2 SUB2Ks, 8 and 9 months old. they’re functionally identical in terms of MCARBO parts installed. One’s a MCARBO edition and the other was a base carbine that I sent off to KelTec to have them install all the MCARBO parts. Both have about 800 rounds through them with no issues until now.

The only difference between them is that the MCARBO edition carbine has a RDS on the Midwest Industries Mini Picatinny Rail Optic Mount, with a Performance Services LLC Handguard Stabilizer under it. The MI optic mount requires that the bolt be open when folded and a lanyard looped around the charging handle to keep it clear and keep it from accidentally releasing and smacking the optic. Both have the MCARBO Recoilless Charging Handle with locking pin installed.

Just broke them both down for their first deep cleaning, and can’t get the bolt/bolt head combo out of the tube on the gun with the optic mount. In the pics you can see my non-optic sub behind the one with the MI mount. It looks like the charging handle hole in the brass bolt is elongated to the rear and has some brass material ridged up behind it. It cycles fine when firing, but won’t budge past the slot in the tube, while the other one allows the bolt head and bolt to just slide right out when I tilt it down.

When folded, it takes some effort to get that MI paracord lanyard lanyard looped around the fat charging handle, and my guess is that the combination of soft brass, applying force to get the lanyard on, and the force on the charging handle applied by the bolt being constantly held open that way all combined to deform the hole in the bolt. Gonna send it to KT and have them figure it out so I don’t do more damage trying to get it out.

Just thought I’d send up a warning flag in case anyone else is running this parts combo.

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overdrill the hole back to round, make a fitted stainless collar to house the bolt. press or thread in, it wont do that again.
what brass does KT speck material wise on that bolt? must not be 360…

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Any updates on this? I’m literally minutes away from buying the brass bolt :grimacing:

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As of Jan 10 2020, sending it in for warranty repair.

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UPDATE:

Got the sub back from KT today (15 Feb 2020). They cleaned and deburred the bolt tube and replaced the damaged brass bolt.

The smith included this note on the repair order: “The H/W brass bolt is softer & malleable, and the tension while held open w/ the paracord will eventually bore out the op handle port. I recommend either going back to the steel bolt when using the Midwest Industries Optic Mount OR use the M*CARBO Optic Mount with the brass bolt.”

So there you have it. KT brass bolt and MI optic mount not a good combo unless you never fold the rifle, which defeats the purpose, IMO. Though I’m a huge M*CARBO fan, I personally don’t like any optic mount solution that has the optic hanging off to the side when the sub is folded. Makes it harder to stow, hide, carry, etc., also defeating the purpose for me.

So, for me, it’s back to the steel bolt with this one. I’ll also find a way to mod the paracord bolt holdback loop so it’s not such a bear to loop over the bolt handle.

My personal preference, YMMV.

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Forget tying the bolt back just move the mount forward if you are using a dot sight you have unlimited eye re-leaf. When you fold the rifle the mount will be in back of the charging handle.

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Have you tried or seen the Mcarbo mount being used in practical everyday situations! I kind of thought the same! But it really is a nonissue! I store mine folded in a side pocket inside my pistol range bag! On top of that I even added a UTG .5" riser so i could get 1/3 cowittness with my Romeo 5! The Midwest had too many cons for me. For starters it set way too high so at close range if you are zeroed at 25yrds you need to hold 4 inches high at 10 yards! It also seemed like it has alot of movement and that stupid retention rope is horrible!

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You know, I honestly don’t know why I didn’t think of that!

Thanks maddog, I’ll take a look at that…

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69Goat, Well I own it now, so gonna make the best of it. I actually like it. The height is fine for me, and there’s really no zero shift or movement issues that I’ve seen so many people talk about with the Performance Services handguard stabilizer.

I agree about the rope, I hate that too. It caused my entire problem…

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I do like how everything folds up nice compact with the Midwest mount! Just tweak it till you like it and have fun with it! There has to be another way to lock the handle back! Maybe some sort of rubber cap with a tab that fits over the end of the charging handle you can grab quick and flip off easily!?

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Another idea is a pistol scope, with a dot it covers the bolls eye & you cant see it. I have a quick release mount with tall rings for the scope this way you can use the scope or iron sights. Once you pick a spot on the rail you always use the same spot so it keeps center. I have solved the problem of adding a second & third mag mount.when I’m finished I will post a picture. Another brother had the idea I just followed through with it. If your in the southern WI northern IL I will be at the Janesville, WI gun show March 7&8 it’s a small show but a good one. The only bad thing about Sub 2 K is it’s just to much fun all the other guns stay at home.

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First did you notice any difference with the recoil with the brass bolt and is the riffle a 9mm or 10 SW? Next drill or use a Dremel to cut away the deformed brass be care not to damage the tube, take the brass bolt out replace with a steel one ( I don’t like brass for this situation. Now take the Midwest mount forward far enough so when the rifle is folded the mount will fall behind the bolt, no tie back is needed plus dot sights have unlimited eye relief. I’m not sure but I believe a stronger recoil spring should be used with a 40 SM bullet has more of a charge. (my opinion only) the springs used are the same for both calibers.

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im going to try something on the whole eye relief thing on the SUBS… using a sight many have never tried…

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Scout Scope, might be possible ?

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this sight is different to get used to. it superimposes the dot in you opposite eye. but you focus on the target not on the sight. ya have to get used to it. both eyes open works fine for me scout mount or rear mount. this is the dot you see in the dark with tritium option
armson pro OEG with tritium

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