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Posted: 4/4/2017 1:18:31 AM EDT
[Last Edit: 4/4/2017 1:20:46 AM EDT by HendersonDefense]
Hi folks,

I've started a few threads in the various forums discussing our experiences with high-volume shooting on our range. We are now approaching, if not surpassing, 860,000 rounds per month We only use our ammo with our weapons as customers cannot bring their own weapons onto our range. We have provided this information to several state and Federal agencies as a form of "test and evaluation" on extended use and our results. That being said, I can provide you with a little insight into what our experience with HK's and HK clones. From this point forward, I will refer to all weapons as HK unless I am providing detail on a certain clone brand/mfg.

The most often used HK at our range is the MP5 followed by MP5K, then the MP5-SD, UMP-45/49 and finally the G3 (or semi the semi HK91 variant). The number one thing I can say about keeping the HK platform reliable is changing recoil and extractor springs. On our MP5's, we change extractor springs every 2-3 days. We've used the MP5-specific copper spring, the stronger steel G3 spring and aftermarket black extractor springs and they all give us about 2-3 days of hard use. We will bend them once before replacing but that's about as good as it gets for us. With the volume of ammunition we are putting down range, there has been no way around it.

The recoil spring is a completely different beast. By not changing it often enough, you will eventually destroy your receiver. The problem with the recoil spring is that it's right in front of your face but it rarely got changed up until recently. We now have a PC in the armory so the armorers can leave reminders to change springs out after three months. We've lost MP5 and G3/HK91 receivers because not changing the recoil springs. The receiver will start to bulge where the bolt carrier bottoms out at the stock. The weak recoil spring allows the bolt to come back with so much force that the rollers eventually to put reverse dimples/bulges on both side of the receiver. If not caught soon enough, the roller will eventually just start getting caught in those dimples and the bolt carrier will stay stuck to the rear. The other issue that occurs is the receiver will crack where the rear stock pins attach. Both issues are caused by the bolt carrier group slamming back so hard that the sheet metal eventually gives. We just recently lost a PTR-91 due to a VERY weak recoil spring that cause the rear of the receiver to crack. This rifle was never run full-auto but is shot daily because it's in one of our more popular packages (sniper package). I did have an original HK SR9 on the line but after five or six months of range use, the factory SR9 stock cracked. At that point I pulled the rifle from the line as it was one of my personal rifles. I never meant to keep it on the line and used it to see how well the package would do.

We keep (+) size rollers to keep the weapons running as the bolt gap slowly fades away. We have a decent inventory and pull and replace as needed. It's a simple fix for the HK platform but once they no longer work, it's time to push the barrel out and replace it. Once a new barrel is installed, you can grab your original rollers and set the bolt gap to those spec's and use them all over again. When replacing the barrel, we've always replaced our locking pieces. I don't know the proper terminology for it, but the angles that allow the bolt and rollers to lock up and go into battery, eventually wear away and won't provide a proper bolt gap. Replacing barrels isn't the easiest task and so I asked Tony Dee from the Gun Store (who has decades of experience on MP5's) to train my guys on when to replace the barrel and went to take it a step further.

We had approximately twenty MP5's that were down due to continued cycling issues. Tony explained to us that since some of our weapons were in the 400,000-500,000 round count, we needed to swap out the trunions. He showed us exactly why we were experiencing so many issues and all the (+) size rollers and new barrels wouldn't correct the problem. I had the staff do complete rebuilds on approximately fifteen of our MP5's. New trunions, barrels, bolt carrier groups, cocking tubes and recoil springs were ordered. After all of the time spend on doing the rebuild program, we've concluded that it's best to just demil or scrap the MP5's and start with new units. The issues we had were not limited to one brand but spread across all of the various manufacturers.

So, this leads to our experiences with all the different manufactures. We have used the following brands on our range: HK, Cohaire, PTR, Century (the HK-53 clone and CETME Sporter), POF, MKE, Special Weapons, Zenith and the Atlantic Firearms variants. Not one of these brands has really outlasted the other. Only one time did we receive a batch of POF's that we had problems with from day one. The rollers must not have been heat-treated properly because all of the rollers cracked within the first week of use. Once we replaced the rollers, the weapons went on to function for thousands upon thousands of rounds. The only model we never used were the cast receivers from Special Weapons or Cohaire, I don't remember who made them. We do have some Special Weapons stamped receivers that are over ten years old but they are finally being retired. ALL of the receivers eventually cracked where the receiver pinches the trunion and we welded them back up. I never considered this a safety or liability issue and they remained on the line.

We pulled thirty plus MP5's this past weekend and will start the demil process. Some of the receivers that were not converted to full-auto will be sold to staff members but they will get the whole firearm for $200 and these include the some of the receivers that just went through the full rebuild. I felt that the receivers were all in such different conditions and age that it would be better to start fresh at this point. We purchased thirty standard Omega MP5's, five Omega MP5K's and five Omega MP5-SD's and five PTR-91's.

I also want to mention the various types of magazines we on the range. We use POF, MKE, the Taiwan-made magazines with parkerized finish and chrome follower as well some HK factory mags mixed in. They all seem to function about the same but the HK factory units do last the longest. The biggest problem with them is weak springs that cause malfunctions. These magazines can get loaded 50-60 times a day and the springs don't last forever. We used to replace the springs with Wolff extra power springs but at this point, it's cheaper and more efficient to just replace the magazine.

I know there are quite a few things that I skipped right over so if I didn't bring it up, please ask me and I will try to answer the best I can. It's been a long day and I didn't mention anything about the various brands of parts we use or how often we replace other parts, which parts fail (other than springs), etc. As with the other threads, I started this thread for all the people are thinking about taking the plunge and purchasing a HK platform. It's not the cheapest platform out there but it's simple and reliable design with SO many choices for replacment parts that they really are a good purchase.

V/R
Ron

eta: Just like before, please forgive any typo's. I already have problems writing things as I hear them in my head but I am beat
Link Posted: 4/4/2017 1:36:19 AM EDT
Interesting info. When doing rebuilds do you stick to the manufacturer's parts for each weapon or do you just mix and match with what you have on hand?
Link Posted: 4/4/2017 1:36:20 AM EDT
Great thread, love these reports.
Link Posted: 4/4/2017 2:02:42 AM EDT
Wow, great post! Thank you Sir!
Link Posted: 4/4/2017 2:12:50 AM EDT
Were any of the mp5s in 40? how did they run? and your guy Robert/Doug why does he always smell of cheese?
Link Posted: 4/4/2017 3:51:25 AM EDT
Do you guys rent HK G36's? If so, how well do they last?
Link Posted: 4/4/2017 4:31:17 AM EDT
Love these threads HendersonDefense, thank you for covering the HK platform!

Two questions:

1) What suppressors are you using for your MP5-SD and what is your cleaning regimen?

2) How are your polymer HKs holding up like your UMPs and G36s if you have any?
Link Posted: 4/4/2017 5:29:59 AM EDT
Thank you for taking the time to make these threads.
Link Posted: 4/4/2017 6:48:56 AM EDT
Uh, any of those junk, 200 dollar semi MP5s left over?
Link Posted: 4/4/2017 10:08:03 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Reaperatm:
Do you guys rent HK G36's? If so, how well do they last?
View Quote
Yes Second this question how do the G36meltalot's hold up.
Link Posted: 4/4/2017 11:01:52 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By rotorblade:


Yes Second this question how do the G36meltalot's hold up.
View Quote
I completely forgot to mention the G36's in that original post. As in my other posts, where I assumed the Gun Gospel was true about barrel life, I also assumed the same was true about G36's melting. We have yet to lose a single G36 receiver after a few rifles have reached the 200,000+ round count. We haven't experienced any cracked, melted or warped receivers to this point.

We have both factory G36's as well as SL8-6's that have been converted. Our conversions have been configured in E, K and C models. These weapons are like SCAR's but in polymer receivers. The barrels and bolts last just as long SCAR's but we have yet to lose any internal rails.

Here are some notes of our experience that really impress me about the G36 series.

- The bolt carrier is likely to fail where the ambi charging handle sits. The spring that keeps it in place will also fail but this doesn't usually happen until the 100,000 round mark. It will fail at the tig-welded portion which is nice because we just sandblast the surface and re-weld it. Losing the spring is a pain because the charging handle will just flop around.

- The factory SL8 barrels can be profiled into a military profile and they last just as long. They have German proof marks throughout and they are cold hammer forged and chrome-lined.

- Gas rings on the on the piston will slowly erode away but last MONTHS longer than the AR platform. They aren't as easy to find but again, they do last quite awhile.

- You do have to cut out a portion of the receiver on the SL8 conversion in order to use a thirty-round magazine. This initially made feel the receiver would fail even faster than a G36 (from all the Gospel online) but that is not the case. We have yet to have any receiver fail or crack, especially in the area where it's been cut out.

- Bolts will last 70,000-90,000 rounds before cracking. You can't use the SL8 bolts when doing the conversion and bolts are a scare item. We try to keep a bench stock of 2-3 bolts at all times because they just aren't readily available.

- We ditched all of our factory magazines and only use Magpul versions. The originals don't hold up to the abuse of being thrown into buckets and all of the abuse that magazines experience during the loading process. We have some Magpul magazines that have been on the line for 2+ years and still function flawlessly.

The biggest downfall to this platform is the availability of spare parts. The best source of parts is from weapons that have been purchased and demilled from police departments around the country. Tom Bostic, who makes unbelievable "clones" of G36's from demilled kits on SL8's, has the same issues that we do. He's been by Battlefield a few times and even offered to put some of his works of art in our vault but I can bring myself to let him do such quality work to just get beat up. During our conversations, it always ends up about getting spare parts. He is working on providing a solution for that but I will get permission from him to speak about and see what his progress is.

The one thing I can say about OUR experience in these weapons not melting down is that maybe we handle our weapons differently? Though the weapons get shot in full-auto everyday, the staff have a different mind set than the average GI. The staff knows that we don't have the Government willing and able to give us more if we break ours and we don't have a supply chain that has as many bolts, carriers and rifles that we can gobble up.

Hope this helps out some.

V/R
Ron
Link Posted: 4/4/2017 11:08:00 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mr_Maim:
Love these threads HendersonDefense, thank you for covering the HK platform!

Two questions:

1) What suppressors are you using for your MP5-SD and what is your cleaning regimen?

2) How are your polymer HKs holding up like your UMPs and G36s if you have any?
View Quote
We only use the TPM Outfitter's suppressors on our MP5-SD's. We've been using them for years and they have gone through some improvements since initially purchasing them but I would take a TPM suppressor over a factory HK suppressor every day of the week and twice on Sunday. The TPM suppressors are very user-friendly and they offer a lifetime warranty on their suppressors. The other thing about their suppressors is that we don't have to wait months and organize some "group buy" in order to purchase them like other mfg's. I email them, they respond and when the Form 3 is approved, they show up... too easy.

The TPM suppressors get cleaned 1-2 times weekly depending on much use they get.

V/R
Ron
Link Posted: 4/4/2017 12:20:30 PM EDT
Hey Ron, great post.

My question regards the life expectancy of typical recoil springs in your MP5s, 91s, etc.

Your timeframe is 3 months for changing them out. Do you have a rough round count for doing so?

I'd imagine that's pretty high.


Those of us that have transferrable sears already know how fast extractor springs can go and to check bolt gap reasonably frequently. I would certainly like to establish my own threshold for the recoil springs though.



Also, have you required any parts replacement in the trigger packs themselves? The burst packs in particular can be pretty complex and I'm not sure if you've run into issues with any of them.
Link Posted: 4/4/2017 12:27:39 PM EDT
Good Stuff! Thanks for the sharing of info!!!!
Link Posted: 4/4/2017 12:46:36 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HendersonDefense:


We only use the TPM Outfitter's suppressors on our MP5-SD's. We've been using them for years and they have gone through some improvements since initially purchasing them but I would take a TPM suppressor over a factory HK suppressor every day of the week and twice on Sunday. The TPM suppressors are very user-friendly and they offer a lifetime warranty on their suppressors. The other thing about their suppressors is that we don't have to wait months and organize some "group buy" in order to purchase them like other mfg's. I email them, they respond and when the Form 3 is approved, they show up... too easy.

The TPM suppressors get cleaned 1-2 times weekly depending on much use they get.

V/R
Ron
View Quote
Thanks Ron,

What is the general process your guys use to clean the TPM MP5SD suppressors?
Link Posted: 4/4/2017 2:20:18 PM EDT
Really neat post, thank you for the info. If you would, could you also give your report on the UMP? Thanks!
Link Posted: 4/4/2017 3:45:12 PM EDT
Awesome!

BTW, do you guys have any full auto PTR91s? If so, how long have they lasted? How many rounds through them before needing to replace a barrel?
Link Posted: 4/4/2017 8:45:36 PM EDT
As always - awesome and informative post. The next time I get out to LAS I'm going to swing by and shoot something...

If I could afford to run 500K of 9mm through an MP5 - that's $100,000 in ammo at $200/K - the cost of replacing the MP5 would be kind of insignificant...

Spooky
Link Posted: 4/4/2017 11:31:55 PM EDT
1.  What ammo (weight, pressure) do you use for the MP5s?

2.  What locking pieces are you using?  Some of those issues with receivers getting beat up can be from using the incorrect locking piece.  iirc, regular MP5's should use the 100 degree LP, while MP5K's with stock and suppressor should use the 80 degree LP and the MP5SD the 120 degree.  On HK91's, going to a #17 LP (36 degree) will noticeably reduce recoil and keep the receiver from getting beat up

3.  How many rounds do you estimate before locking pieces need to be changed?
Link Posted: 4/4/2017 11:36:38 PM EDT
P7 notes?
Link Posted: 4/4/2017 11:49:21 PM EDT
i enjoy hearing these reports. Been to Battlefield twice and shot the mp5,mp5k,mp5sd,and g36k. Will definitely go back, but my money lasts longer at the strip clubs.
Link Posted: 4/5/2017 12:50:43 AM EDT
Nice to read this. Next time I am in Vegas, I want to shoot an MP5 of some kind. That, and a SIG-553 if you have one. If you do, I'd love a similar thread on SIG type rifles. 550/3 series and maybe the MCX if you have received any of those yet.
Link Posted: 4/6/2017 9:55:52 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By mcantu:
1.  What ammo (weight, pressure) do you use for the MP5s?

2.  What locking pieces are you using?  Some of those issues with receivers getting beat up can be from using the incorrect locking piece.  iirc, regular MP5's should use the 100 degree LP, while MP5K's with stock and suppressor should use the 80 degree LP and the MP5SD the 120 degree.  On HK91's, going to a #17 LP (36 degree) will noticeably reduce recoil and keep the receiver from getting beat up

3.  How many rounds do you estimate before locking pieces need to be changed?
View Quote
- We use a mix of Magtech 115 and 124 grain FMJ in all of our 9mm's

- We use the appropriate locking piece (HK when possible) in each platform but I didn't know about using a #17 in the HK91. I want to go back and look at the PTR-91 that we deadlines and check to see if there any markings.

- To be honest, I don't know how often the armorers replace them. The inspect the angles for wear and if it "looks" like the area that is polished from use, swap it out.

V/R
Ron
Link Posted: 4/6/2017 10:39:53 PM EDT
Question on MP5 magizines.
Are you using ball or hollow point ammunition? And are you using both Curved and Straight magazines ?

Old web statement has been that Straight magazines were a bit picky with ammunition other than Ball ammunition. Just wondering if you've noticed any correlation on this.
Link Posted: 4/6/2017 10:51:34 PM EDT
In on one.
Link Posted: 4/7/2017 12:09:58 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By thinice:
Question on MP5 magizines.
Are you using ball or hollow point ammunition? And are you using both Curved and Straight magazines ?

Old web statement has been that Straight magazines were a bit picky with ammunition other than Ball ammunition. Just wondering if you've noticed any correlation on this.
View Quote
Only ball ammo in curved mags.

V/R
Ron
Link Posted: 4/7/2017 1:03:34 AM EDT
Great info. Thanks for posting.
Link Posted: 4/7/2017 3:59:17 AM EDT
Thanks for all the great in Ron. Very excited to get this HK specific info.
Link Posted: 4/8/2017 7:33:43 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mecha_Loopy:
Thanks for all the great in Ron. Very excited to get this HK specific info.
View Quote
How many rounds would you guess through your semi PTR 91's/HK 91's weekly? 
Link Posted: 4/8/2017 1:54:46 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By slimslade:
How many rounds would you guess through your semi PTR 91's/HK 91's weekly? 
View Quote
I will start asking the armorers for more info regarding the HK platform and keep this thread updated.

V/R
Ron
Link Posted: 4/8/2017 5:32:58 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HendersonDefense:
I will start asking the armorers for more info regarding the HK platform and keep this thread updated.

V/R
Ron
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HendersonDefense:
Originally Posted By slimslade:
How many rounds would you guess through your semi PTR 91's/HK 91's weekly? 
I will start asking the armorers for more info regarding the HK platform and keep this thread updated.

V/R
Ron
If you think about it, ask them about part replacement intervals on the semi's also, extractors, recoil springs, etc. 
Link Posted: 4/10/2017 8:02:11 AM EDT
Do you guys have one of the HK clone rifle with a buffer tech buffer or the HK heavy Buffer installed?
Link Posted: 4/10/2017 4:05:02 PM EDT
[Last Edit: 4/10/2017 5:20:05 PM EDT by APSArmament]
For what it's worth, the M240 series of guns, as well as the M2MG series does not give specific round count or even spring measurement specs for replacement and use a similar captured recoil spring system.

Rather there are wear indicators used to determine spring replacement as well as inspection for broken coils, etc.

I would suggest regular inspections for flat/worn coils on the springs and of course broken coils. Inspection of the back plates and rear of the bolt carriers for impact and deformation as well as the already noted dimpling of the inside of the receiver by the rollers like you already do.

On guns with a recoil buffer such as the HK91 series, replacement of buffer spring or even the entire assembly at regular intervals may help. Upgrading to a heavier buffer might also help extend receiver life.
Link Posted: 4/10/2017 9:12:39 PM EDT
My hk53 rear pin is pushed back and receiver cracked a little around it, roller dents visible on the outside and rails gouged a bit on the inside. I got it used, probably pretty well used. I replaced the recoil spring and the old one was probably 1.5" shorter than the new one.
Link Posted: 4/10/2017 10:41:10 PM EDT
Always a sucker for these kinds of threads.....thanks.
Link Posted: 4/10/2017 10:53:33 PM EDT
Great info Ron, much appreciated! This info will help with our clones
Link Posted: 4/12/2017 8:20:20 AM EDT
Thank you for taking the time on this!

I'm also curious on how often you replace the recoil springs?
Link Posted: 4/12/2017 2:51:27 PM EDT
Thanks for sharing this treasure trove of knowledge!
Link Posted: 4/12/2017 6:20:24 PM EDT
[Last Edit: 4/12/2017 7:01:32 PM EDT by 55Kingpin]
Thanks for sharing. Really enjoy reading your various threads, very helpful info and I sincerely appreciate your time and effort.

I have no explanation for it, but there's just something about an HK roller-lock gun.....



On the MP5s do you all use the twisted dual spring Firing Pin spring?

Also, what roller retainers are you using? I've had great luck with the "S" shaped type.

Are you utilizing heavy buffers (or any other upgrades) for the G3/HK91 type rifles?

Godspeed,
Chase
Link Posted: 4/14/2017 6:04:58 PM EDT
Tag and thanks for the awesome information you've provided.
Link Posted: 4/16/2017 3:00:03 PM EDT
when you say it's cheaper to just replace the mags, is that because you 1) get a screaming deal on HK mags 2) are replacing with POF or Taiwanese mags or 3) factoring in labor/time?

great thread as always. thanks
Link Posted: 4/16/2017 3:07:26 PM EDT
Ron - Side question:

Have you done a write up on silencers (in general) yet?  If so, can you please provide a link.

Also, what do you guys use to clean up your silencer 3 lug mounts (assuming you use them)?
Link Posted: 4/16/2017 6:29:41 PM EDT
[Last Edit: 4/16/2017 6:31:07 PM EDT by HendersonDefense]
Just got back in town yesterday from a family Spring Break vacation. I will try answer all the questions but the first thing I asked today when I stopped by for the staff Easter egg hunt is "How did the extractor and extractor springs hold up".

Well, they are on the line two weeks now with ZERO failures! This is SUCH good news for guy and gals who love spending time with their MP5's (semi or full). This has to be the single greatest update that could ever be done to the MP5 roller-lock design.

The owner said it wasn't a problem to mention his company so it's Moore Advanced Dynamics.

V/R
Ron
Link Posted: 4/17/2017 2:17:13 PM EDT
Link Posted: 4/18/2017 3:38:57 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By John_Wayne777:


Exactly what upgrade are you referring to, here? Did H&K release a new bolt design?
View Quote
These are the new bolts from Moore Advanced Dynamics. They use a conventional coil spring with the extractor that doesn't wear or break after 2-3 days.

V/R
Ron



Link Posted: 4/19/2017 2:21:04 AM EDT
have you researched and done experiments on making the receiver HD like the PSG-1, has that funky rails welded on the sides to stiffen the receiver.

Maybe..its needed on the Mp5 also.
Link Posted: 4/19/2017 1:50:22 PM EDT
Link Posted: 4/19/2017 11:11:14 PM EDT
[Last Edit: 4/19/2017 11:11:47 PM EDT by Hyperformer]
I found this on Moores website.

300 BO in a roller lock.

Link Posted: 4/20/2017 8:11:04 AM EDT
[Last Edit: 4/20/2017 8:15:55 AM EDT by R3dundantC]
Originally Posted By HendersonDefense:
purchased thirty standard Omega MP5's, five Omega MP5K's and five Omega MP5-SD's and five PTR-91's.
View Quote


Will you give us an update on how the Omegas hold up in a few months? I've got one thats been basically 100% and I am very pleased with but others have seemingly had a few problems with them. You've got a pretty good sample size to see how well they work over the long run.
Link Posted: 4/20/2017 8:55:15 AM EDT
Thanks again for the updates, much appreciated!
Link Posted: 4/20/2017 9:23:22 AM EDT
This is a great thread. Thank you so much for the replies, and I hope you come back and visit it regularly!

How about the internal parts like the trigger pack components and the magazine catch/release? Do these ever wear out?
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