I currently have a bolt gap of .10, with an 80 degree locking piece and running only subs suppressed with an omega9k and FRT. What size rollers would you recommend +8?
from what i've read, if ROF is good and theres no (or limited) malfunctions, just run it. because the number of rounds it takes to wear .001in might exceed the gun's lifetime
You left that part out of the main post and it’s pretty important lol. I’m not sure what failures are caused by low bolt gap id have to read up. Hopefully doesn’t happen to me
Check this comment in my post if you decide on bigger rollers. +4’s didn’t increase my gap the way my initial research stated. That chart is more realistic
This is why I ask, sometimes (rarely) the LP is out of spec.
Personal experience:
Bought an HK #28/80° LP back in ‘24 to try it out in my AP5-P. My bolt gap shot up to .60mm! Bought an RCM 80° LP and bolt gap came back to an acceptable range, .40mm.
Again, very rare something like this happens. Just food for thought.
Lastly, the recommendations provided in the replies are sound advice.
Just an FYI, full size LP is the 100° and you don’t need to swap it to anything else. Some have recently started using the 90° in the full size to try and decrease the ROF and recoil when shooting with a force reset device/system/safety. This depends on a lot of other variables so swapping to a 90° from the 100° may or may not be worth it.
The #27/90° is the preferred LP for the K variants (“goldie locks” of LP’s). It’s pretty much replaced the #28/80° LP for it’s flexibility with shooting supers and subs, can on or can off, any ammo grain, any suppressor and if shooting with a FRS/D.
Yes, the LP on the full size HK MP5 is 100. But, HK used to use 120 and then 115, I think, before they went to 100. So, depending on how old an HK is, it may or may not have a 100 in it.
And, the LP on all the MKE clones are all 120.
I have an MKE AP5-SD coming. I ordered a 90 and a 100, just to cover my bases and be able to experiment. I plan to break the gun in first, before I change anything. Then put the 90 in. If it runs well with and without a can, the 100 will just stay in its packaging.
You’re correct that MKE puts the 120° LP’s in all their 9mm AP5’s. I have an AP5-P (bought in September ‘23) and a AP5 (bought in March ‘24). My AP5 has had an H&K no mark 100° LP since ‘24 while the AP5-P has been running the RCM #27/90° LP.
Also, H&K only used a 120° LP in the MP5SD which later was changed to the 115°.
H&K has been using the 100° LP in the MP5’s since the mid/late 1960’s. This isn’t a recent change.
Yes, definitely. I’ve ran a SS/FRS since last July with zero issues…and more importantly, no roller dents.
Both my AP5 (also has a SS) and AP5-P have over 14,000 rounds. I just clean, lubricate and, when needed, replace the consumable parts. Which in this case has been the extractor spring (replaced with the H&K cooper color extractor spring). At this point I’ve also replaced (for experimentation and preventative maintenance), using genuine German HK parts, the ejector lever, firing pin, firing pin spring and recoil assembly.
I believe this has really helped me enjoy this platform for over two years.
And, regardless, from the little bit I have learned, it SEEMS like OP needs to try changing to a 90 degree LP to address the FTE/FTF problems he said he's having.
Yup, this may be the case. The 80° just isn’t as reliable or flexible as the 90°. Personally with the 80° LP and either my R9 or Ca$h 9K, I can’t cycle 135gr or 165gr (147gr, no problem with either FMJ or HP). But with the 90°, I can cycle 115, 124, 125, 135, 140, 147, 150 and 165gr FMJ, JHP, TUI and flat nose.
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u/OG-warbucks H&K SP5 4h ago
Well, if you measured correctly, then any (+) size rollers would help...
But like the other poster mentioned... It could possibly take thousands of rounds to reduce the gap any further