Teufelshund Tactical Heckler and Koch Bolt Gap Review

[@Jrhoney]

That is the most comprehensive demonstration of roller delayed blowback I've ever seen. That is a really cool cutaway demonstrator!

[@teufelshundtactical]

JRhoney Thanks. As you will see with my other videos, it’s what I do.

[@AgoristAlex]

Love the look of the no Tri-Lug barrel on the K’s. Thanks James 🦃

[@nickm8651]

A very nice professional video. Great job explaining everything perfectly. Your the GOAT, cheers!

[@anthonyhablinski9852]

Thank you Sir, really appreciate you sharing your knowledge with us all.

[@armandgun]

Excellent video, thank you!

[@reconhell1]

Can’t thank you enough for the education you provide for my new favorite system. Really appreciate you.

[@teufelshundtactical]

My pleasure. Much more to be gained on the channel and through attending our training courses.

[@scottsmith7424]

That has to be the best explanation of this roller system I have ever seen. Saving this one to watch over and over the more I become familiar with my PTR 9kt. I've got to change out my locking piece and possibly install new rollers if the gap is off.

[@teufelshundtactical]

Thanks. Check out the channel for more H&K knowledge bombs.

[@mini14jac]

Thank you sir. I feel like I'm learning a lot about the MP5 platform by watching your videos.

[@sparkyboots]

Best video out there on the roller install, thank you! You have been a big help.

[@teufelshundtactical]

Many thanks. You'll find an entire channel dedicated to H&K knowledge and experience.

[@djsity]

I recently bought my first roller-locked gun, this was super helpful. Thank you for posting!!!

[@montydyer]

This answered so many questions, thank you James! We really appreciate yor content.

[@teufelshundtactical]

Monty Dyer My pleasure, as always.

[@medikpac7105]

I know this is an older video but thank you. It made switching some +2 rollers in a breeze.

[@Katya5cat]

Excellent demonstration Thank You !

[@John-ro3vu]

Excellent Video, James. This is a confusing topic for a lot of people and it is great to have It Explained so concisely and with cutaway models to facilitate learning for those unfamiliar with the system.

[@teufelshundtactical]

John Zelna Thanks. Just sharing the knowledge.

[@MartinsMachines]

James, love your stuff but I do believe you have the effects of too small or large of a bolt gap reversed in this video. The smaller the bolt gap the larger the delay with zero bolt gap being full lock. The larger the gap the less delay and closer to straight blowback you get. In the video you say the opposite at multiple points. Please correct me if I am indeed wrong. Thanks

[@teufelshundtactical]

You’re answering your own question. I would want my bolt gap to be at the top of the acceptable range.

[@philgamboa2906]

Continued learning on the platform for me. Thank you for the deep dive into bolt gap and and how to adjust when needed. Very informative and well made video. Thank you!

[@teufelshundtactical]

My pleasure, as always.

[@stephenlozano2816]

Recently purchased my first roller delayed blowback gun (PTR9CT) interesting to see how this system actually works. Well done 👍🏼

[@1966Hemi426]

This was an amazing explanation of the bolt gap. Very thorough. Thank you.

[@JosefCharoni]

I was always under impression an undersized bolt gap casued too much delay and essentaiily locks the action making it single shot and a too large of gap had too little delay and caused excessive bolt speed and recoil.

[@NormanTotsch]

Great and most helpful video!

[@johnbauby6612]

Very comprehensive. Thanks for taking the time to make the video. So on a new build, if the barrel is not pressed in far enough or pressed into the trunion too far - what would we see in either situation? Pressed in too far would result in too little a gap and not pressed far enough would result in a larger gap?

[@iMurk903]

Awesome information. I just bought a MAC 5 and I'm wondering if anyone could tell me if I need to change the locking piece if I'm going to run it suppressed with a brace

[@teufelshundtactical]

I don’t know what that is. Changing the locking piece is only recommended for the MP5K PDW when using a stock, full auto and a suppressor.

[@iMurk903]

@teufelshundtactical The MAC 5 is a Turkish clone like the century arms. I believe they are made in the same facility. I've been reading into the platform and people are recommending you change the locking piece to 90-100 if you run it suppressed to mitigate roller dents. I have no clue though. Bolt gap measures .33mm

[@jannesto2577]

Love your info and quality of instruction! Hope you can cover someday MP5 barrel replacement.

[@masakuniyoshikawa8160]

Exactly what I wanted to learn...thank you so much for putting this together!

[@dbuck806]

How much force should be used on the feeler gauge when checking bolt gap? When it just falls in place with no force? Sorry and thank you for your time.

[@teufelshundtactical]

Keep moving up in size until you have to really apply significant force to insert it.

[@kaddyman61]

This is an overall great video but may I make a recommendation that I am sure someone else may have mentioned, I would have left the cutaway on the table in frame while explaining the mechanics of the bolt and rollers and locking piece, etc. but other than that thank you for this information!

[@leerx7015]

I found a stahlwille with the thickness that goes from 0.05 - 1.0 mm, in 0.05mm increments. Is this the right one to buy?

[@leerx7015]

I'll take that as a yes...

[@CTTH100]

I understand there's an acceptable range but just curious why a new HK SP5 not be shipped with a factory .45 mm gap. What would cause it be be lower....materials, manufacturing process? Mine SP5 has .35 mm. out of box. My MKE AP5-M had .33 mm.

[@teufelshundtactical]

Every SP5 I have inspected, either on my workbench or when teaching a training course, has been .45mm. I can’t see what you’re seeing but first guess is you’re doing it wrong.

[@GunWodan]

I‘ve put around 500 rounds through my HK SP5 so far (mostly suppressed) before I even became aware of this bolt gap metric. Just measured it and got a tight fit on the 0.40mm feeler. Is that considered normal break-in or cause for concern? Thanks very much for sharing!

[@teufelshundtactical]

That is fine and you’ll probably never shoot enough to have it ever be a concern, that is unless you start attending our Teufelshund Tactical MP5 Operator Courses.

[@GunWodan]

@@teufelshundtactical thanks so much for your response. It‘s priceless to be able to connect with experts around the world regarding such extremely technical details. Would love to attend one day when I visit the US. Beste Grüße aus Deutschland 😄 keep on posting your awesome content!

[@jwmeitzler2671]

Just purchased a factory new MAC 5. I am a FFL and it came right from my jobber who just got a batch in from MAC/SDS Imports. Firearm has not been fired, totally clean. Bolt gap was 0. No gap whatsoever.

[@kirk4478]

I like the flatop full auto converted Sp5k BCG🤙As always,,the BEST HK info available,,bare none!!

[@hhe5218]

Hi James, do you know if the HK locking pieces in the HK91 are the same as the ones in the 770 / SL7? I have not been able to find an answer to this anywhere, hoping you can help. Really appreciate your videoes👍

[@LenHernandez]

Thank you for this video. Clear and concise!

[@teufelshundtactical]

Thanks. Lots more knowledge bombs on H&K weapons on my channel.

[@MidTennSLIM]

I've recently been having pretty extreme failure to eject with my zenith. Put a new ejector lever. New extractor spring(2 times now) searching for possible causes

[@teufelshundtactical]

Too many variables without seeing it. I recommend you contact Zenith for warranty service.

[@yomust0of]

My question is how are those channels for the rollers machined? Looks like either a real small endmill or some ECM machining

[@hahtsauce]

i really need to take one of your armorer classes

[@teufelshundtactical]

Indeed

[@kirk4478]

James what kind of finish is that on the bolt carrier shown?? I know it differs from the MKE as they are black and the HK cocking tube support and Bolt carrier seem to have that same off black mayby even greenish color to them.I have a brand new Zenth Z5p i have just never fired as i have quite a few other weapons i had to break in first and ammo has been tight the last couple of years. EVERYTHING is perfectly straight and the welds are even better than the sp5,,only the paint has bubbled just above the trunion weld and i scratched it lightly and the paint came right off exposing the parkerizing. I figured no big deal and then i noticed it up at the back of the cocking handle slot as well where the perfect welds are and the paint just flaked off about the size of the top of a plastic pushpin that we use to mount things to walls. Not big,,jus very dissapointing. I Do Not want to turn the gun in as everything is soo straight and the welds are soo perfect that with my exposure to mayby 20 or so MKE and HK MP5's and K models by Zenith and Century i have not seen one as perfect as this one so i dont wanna turn it in so even though its never been fired,,iv decided to have it blasted with Aluminum Oxide and have it refinished. Iv been looking at the RDTS 3 step finish that seems to be used on a lot of high dollar class 3 MP5's. They appear to have that same greenish BCG and charging tube support color when finished. Can you recomend someone or mayby let me know if you have any experience with RDTS?? It sounds like they have the actual NAVY Ocean Environment coating that was applied to Navy Seal's weapon of all types in the past. Im on in $1700 on this gun,,i have not SBR this one yet because of this paint issue. Your the Master in this area and you KNOW the diff in the MKE finishes and the HK finishes. Any help would be great. An SP5K is going for 5 grand as of today. Im sure i can keep my all in under 3500 if i play my cards correct. Any help or advice would be GREATLY APPRECIATED. Thanks James,,Kirk🙏🤙

[@teufelshundtactical]

RDTS or his son, HK Ralph Jr (you can find him through Facebook) can help you with a refinish project.

[@kirk4478]

@@teufelshundtactical Thank you James🙏🤙

[@SoldierO7]

Thank you for explaining this so clearly! Just one additional question however: If the acceptable range begins at 0.25mm, wouldn’t any feeler gauge beneath that width also fit into the bolt gap? My Z5-P with the RCM 80° locking piece won’t accept anything past 0.35mm, but 0.25mm and under slips right in.

[@teufelshundtactical]

Thanks. It would, you can go as low or as high as you want in your inspection.

[@SoldierO7]

@@teufelshundtactical Good copy! So would you say that if a 0.25mm gauge fits with mild-to-moderate play after switching out a locking piece, the bolt gap might be undersized? In which case you lose the “roller delayed” part of the blowback operation?

[@teufelshundtactical]

@@SoldierO7 You need to be somewhere between the minimum and maximum range for bolt gap.

[@shawnwillis7561]

A lot of H&K knowledge here. Glad I found your channel. Subscribed

[@michaeldavis2524]

Love your info and quality of instruction!

[@teufelshundtactical]

Michael Davis That’s the goal. Thanks.

[@TopShotDustin]

ah see you should have sent this video to me last year lol. Thanks bud.

[@teufelshundtactical]

Haha. Yep. Most people find me and the info I provide after they really needed it.

[@ace1gun]

My JLD PTR91 Bolt gap is at 0.10mm and has all HK internals bolts would that be safe or should it need the Plus Rollers?

[@teufelshundtactical]

The video covers what the acceptable range is.

[@ace1gun]

@@teufelshundtactical Yea I watched it, mine is barely at the acceptable range so I guess what would you do in my situation to address bolt gap at the lowest end of tolerances ?

[@johnblanchard7871]

Lots of answers! Thanks

[@Darkness-ln9by]

Greta video as usual James! Top notch!!

[@leerx7015]

I found an HK91-G3 LOCKING PIECE from rtg parts. Says the locking piece is very important for managing proper bolt gap. It's only 13 dollars... is this what I need for my hk51? I still don't understand why I need this bolt gap LP and a 17/36 LP for shooting suppressed? Is the bolt gap LP just for you testing and then removed before shooting? Or does it stay in along with the 17/36?

[@teufelshundtactical]

I don’t know what you are talking about. The locking piece is one of the components of the bolt group. Bolt gap is the measurement of space taken between the bolt carrier and bolt to inspect if your weapon is in the correct spec range. This is done with a feeler gauge. H&K made a bunch of locking pieces for different models and variants. H&K never made a HK51, so there is no specific locking piece for it.

[@abitnutz6747]

I haven't seen a roll-pin punch like that before. What are they called? Can you tell me where to get a set? Thanks...

[@teufelshundtactical]

Try HKParts.net

[@shawnwillis7561]

I'm currently trying to barrel a trunnion for a homebuild mp5k style gun. Do you think that 0.45mm is the best gap to set the barrel for pinning at so that when the barrel settles from use into its final position that it will be in the middle? I guess is it better to pin it at the higher range rather then the lower range

[@teufelshundtactical]

I would recommend you reach out to a builder for their best recommendation.

[@hahtsauce]

James would you mind helping me out... do you go all the way down to the locking piece with the feeler gauge or just the initial gap between the carrier and bolt? My bolt gap reading is too large initially but if I push it down to the locking piece it tells me that the gap isn't too large.. im right under the max specs if i go to the locking piece with the feeler gauge. If i don't go to the locking piece my gap is way too large.

[@teufelshundtactical]

I insert the gauge all the way in.

[@brycegill2022]

Really appreciate this great info.

[@apsirotin]

Thank you for this.

[@gregsicinski8138]

Teufelshund, do you know where there might be cutaway bolts for sale? Specifically for the HK91? I have a much beloved pre-ban HK91 and this would make an excellent addition to my gun room. Thank you.

[@teufelshundtactical]

These have not been produced since the 80s. Finding one for sale would come from a private collection and can cost up to $5000 or more.

[@gregsicinski8138]

Wow, that's quite a bit of money but the detail is incredible, so well worth it for your highly informative video. Thank you very much!

[@teufelshundtactical]

@@gregsicinski8138 Agreed. I certainly did not pay that much for mine, but that is the reality of the current market.

[@fnarhkfreak]

Hello, I have a rifle bolt gap that is in spec but the rifle is single shotting, it worked fine before but now it does this? What else could it be? Thank you in advance.

[@teufelshundtactical]

Without seeing it, I would not know. Maybe improperly assembled or with the wrong ejector lever.

[@fnarhkfreak]

@@teufelshundtactical it barely unlocks could it be barrel length and ammo?

[@teufelshundtactical]

@@fnarhkfreak As I said, without seeing it, I don’t know.

[@fnarhkfreak]

@@teufelshundtactical ok thank you. Do you have a video explaining the locking piece and how it effects operation in different circumstances?

[@teufelshundtactical]

@@fnarhkfreak This video explains the locking piece. It provides the amount of delay. The steeper the angle of the shoulders, the less delay.

[@anthonyjimenez9725]

Is the .25-.45 mm spec the same as the g3?

[@teufelshundtactical]

Yes

[@anthonyjimenez9725]

@@teufelshundtactical I appreciate that. Have a g3 parts kit from Portugal that I'm working on.

[@F4iGuy599]

Great video!

[@InfoNotWars]

Thanks man

[@jimtheedcguy4313]

With those displays being so scarce, I wonder if anyone has 3d files to make a printed one.

[@teufelshundtactical]

You don’t need a 3d file. You just need a bolt group, a block of wood and the skills and tooling to do some cutting.

[@gregkunkel708]

Excellent video!