WTH? Serious? you cant buy off the shelf 115gr for your SD. That just sux and I dont care what the reason is. Dang. That'd be a deal breaker for me personally.My RTDS conversion wont shoot any 115gr and I have tried alot of differet brands (I have never hand loaded for it though), but as other have said it eats 124gr like candy. I typically use Remingtion as well as the odd box of Magtech and Wichester white box.
In my experience, if one is intent on shooting 115gr, make sure to use the previous HK 120 degree LP receomendation (more angle = unlock sooner). I have a RCM 120 degree LP that I bought and used with my SW SD but have not used it since taking delivery of my RTDS SD conversion. Now I have the current HK spec 115 degree LP in my SDs so its no surpise there that non +P 115gr is a no go. I tried alot of 115gr ammo to see if indeed that was the case and it is for my guns with my 115 degree LP and can. Also as others have said, most 115gr is not as hot as typical 124gr loads which the SD was designed for from the get go. Who knows a SD and with a can having a smaller volume (say a RCM can) than my RTDS can might cycle on std 115gr non +p ammo and a 115 degree LP.WTH? Serious? you cant buy off the shelf 115gr for your SD. That just sux and I dont care what the reason is. Dang. That'd be a deal breaker for me personally.
Yup, they still will do that in fact if you dont provide a lp when you do the conversion and dont want a RCM lp.Interesting thing about Ralph's SD build, he doesn't change the locking piece, he uses a standard 94 locking piece and modifies the angle...at least that's what he did for years. That's old school, from the days when you couldn't get factory full auto parts.
@RDTS, sorry to revive an old thread, but I was curious on your thoughts on 147 grain ammo being ran through your MP5SD firearms / HE suppressors.I know this is an old thread but thought I'd provide some info. In the past since we have been building our "MP5SD HE" since the late 80's we did machine a German MP5 locking piece to open under the lower pressure that an MP5SD has due to the porting. All our builds for probably the last 8 years have had the RCM 120 degree locking piece. HK transitioned to 115 degrees and the older 120 degree were hard to find. Adam (HKParts) would have RCM do a special run of 120 degree since we would buy 40-60 at a time. Ours MP5SD HE with a 120 degree will cycle NATO spec 115g rounds all day. We recommend American Eagle Red Box (Federal) as on the box it's states 1180 fps which we verified out of a MP5K 4.5" barrel. Our MP5SD HE shot this ammo at 1040 fps and our post sample German HK MP5SD shot the same ammo at 920 fps. Also thru some independent Suppressor testing on a Silencer forum way back 10 or more years ago, verified our MP5SD HE was 1 to 2 db quieter than an HK MP5SD. Any questions please call or email. I try to answer the phone if I'm not on the Shop equipment as I got sucked into the lathe one time when the phone distracted me, lol!
I believe even HK does not recommend Subs in their MP5SD's. It's designed for NATO spec 115gr/124gr. The problem with subs is they are all over the board on velocities and weight. The only standard I consider for subs is IMI blue tip. I believe (might be wrong) that the heavier bullet stays in the bore longer and depending on powder type, burn rate may jack up the pressure causing excessive recoil in the carrier mechanism that over time may damage the gun. I tell my customers if you must shoot subs pay attention to recoil, make sure you have a buffer especially if your running an A2 stock as most of those have a steel plate inside that the bolt carrier will bang against possible causing your roller to ping out and eventually dent your rails. I drill and tap that plate and install a flat H buffer on A2 stocks. Of coarse if your making a video to show how quite your 8" Suppressor is you have to run subs, lol. Most videos with short MP5SD Suppressors that appear to be as quite as the 12" Suppressors are running subsonic ammo, just physics. But in my opinion, what's the point to an integral SD running subs?@RDTS, sorry to revive an old thread, but I was curious on your thoughts on 147 grain ammo being ran through your MP5SD firearms / HE suppressors.
Ignoring terminal ballistics downrange, any functional issues if a guys is only goofing of at the range and shooting at paper with one of your builds while running 147g ammo? I know that your porting design keeps the velocity about 100 FPS higher when slowing 115 / 124 grain ammo to subsonic velocities as compared to a factory SD's barrel porting. What do you see with 147 ammo ran through your integrally suppressed guns?
Well, as a reloader I can keep pretty consistent control over standardizing velocities / projectile weights. I like 147 loadings in general, as it stays subsonic in my other non-ported firearms. It'd be nice to only have to stockpile one type of ammo for shooting suppressed.I believe even HK does not recommend Subs in their MP5SD's. It's designed for NATO spec 115gr/124gr. The problem with subs is they are all over the board on velocities and weight. The only standard I consider for subs is IMI blue tip. I believe (might be wrong) that the heavier bullet stays in the bore longer and depending on powder type, burn rate may jack up the pressure causing excessive recoil in the carrier mechanism that over time may damage the gun. I tell my customers if you must shoot subs pay attention to recoil, make sure you have a buffer especially if your running an A2 stock as most of those have a steel plate inside that the bolt carrier will bang against possible causing your roller to ping out and eventually dent your rails. I drill and tap that plate and install a flat H buffer on A2 stocks. Of coarse if your making a video to show how quite your 8" Suppressor is you have to run subs, lol. Most videos with short MP5SD Suppressors that appear to be as quite as the 12" Suppressors are running subsonic ammo, just physics. But in my opinion, what's the point to an integral SD running subs?
