Re: H&K 300 any good?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JFK52</div><div class="ubbcode-body">The real part that wears on these rifles is the "M" shaped recoil buffer. Get an extra one if you can. I have a HK 300 and have put several thousand rounds of .22 magnum through it and replaced the buffer once already. It also is finicky about some types of ammo that fail to cycle the action. My 300 is just deadly accurate with Winchester 40 grain JHP. An HK 05 scope mount is the best way to mount your optics. You have a great rifle, enjoy it. </div></div>
JFK52, how did you, where did you, when did you get your replacement buffer, and what did it cost, please?
I learned this work-around on HKPro.com/forum but so far haven't had to use it yet: An MP5 a3 "H" buffer, trimmed down to roughly replicate the notched "M" buffer for the HK-300, can be substituted. MP5 buffers are readily available and cost less than $50 ($10.95 is the price for the seller whose image I use below).
Here is a picture of the HK-300 buffer (actually, a scan of the buffer within its retention ring, saved as a jgp file). The tall sides of the M are for the trigger assembly to fit into, and the short cross bar (the v of the M) is short so that the firing pin at the back of the bolt has a place to "fit" (non-gunsmith wording and reasoning, here). This view is of the side facing the bolt. The buffer (a hard plastic or other synthetic material, as almost all buffers are made of) sits into the buffer retention ring (metal).
Here is the bottom side view. The buffer sticks out of the retention ring:
HK apparently never sold these as independent buffers, that is, as the buffer without the retention ring. Instead, the ring came with the buffer already glued into place and HK called it the total item the "buffer."
So, if your buffer is worn out and you can't find a replacement, whether good used one or new one, the H-buffer trick might work for you. Here is an image of the MP5 a3 H-buffer.
Scrape out the old one or remnant, if it's still there at all, and cut/shape/fashion the H-buffer to roughly resemble the M-buffer in shape and size, and glue it into the retention ring. The egg-shaped part of the H-buffer is obviously not needed.
Make sure you compare with your old buffer retention ring and old buffer--the buffer for the HK-270 is very different, even though the basic rifle design is almost the same as that for the HK-300, and also the HK-300 was changed beginning with S.N. 15,000 to have a bigger, heavier bolt, and some parts are not interchangeable for the HK-300 for S.N. less than 15,000 (receiver cap for sure, and I'm guessing the buffer retention ring and buffer are different sizes, too).
I own several of these fine rifles (HK-300). None of my Hk-300's has the rear sight missing, and I've never seen one advertised that does (in contrast to the H&R 700 or 700DL 22-wmr rifles, which frequently have both the rear and front sights removed and a scope base and scope mounted instead; I mention the H&R because it's the closest comparison to the HK-300 that I know of; I own 3 of those, too). I think instead that the HK-300's integral scope mounting base on top of the receiver can fall off--?loosely soldered on?--and that's perhaps what was meant in the post above about the rear sight being absent?, as there is no reason to remove the rear sight to mount a scope on the HK-300. The HK-05 Quick Detach base works just fine ($350-450 without rings and ($400-600 with rings); this same mount also works for the HK-630, 770, 940 (those are HK's common caliber centerfire hunting rifles), and a few other of its rifles (I think the SL7, maybe?), so there are quite a few of those available and they're useful for more than just the HK-300, they're not just a luxury item. B-Square also made a custom base for the HK-300, still available and runs $50 to $100, but it's only for rings--modern holographic sights won't fit it (dimensions on the holographic sight base are too big, won't fit flush onto the B-Square base, as the sight base sides interfere with the side screws on the B-square mount). However, there is now a short-base holographic sight being sold that might work--I hope to check one out soon.
Hope this is helpful to someone.