View Full Version : HK 51 Collapsing recoil assembly stock usable on 91

open ear shooter
August 08, 2015, 05:23
are there any benefits to using the HK 51 collapsing recoil type assembly on a Regular PTR 91 !?

August 08, 2015, 07:52
I've wondered this myself. Thanks for posting. Anyone know ?

August 08, 2015, 10:25

First, there is no such thing as an HK51. Never was. Something that individual gunsmiths adopted to use as a name for a .308 in 53 configuration. That means that each one is different. My Urback won't fit your RDTS, which won't fit your PTR. The only advantage to the PTR Is now there is a volume so they have become more standardized.

The recoil spring & guide is a different length, as is the bolt carrier. These three things need to be in perfect harmony before you even look at changing the locking piece.

So no, they are not interchangeable.

Personally, after much consideration, I dumped my Urbach 51 and built my own G3K on a JLD "c" rifle. It's 12.8" and uses all standard G3 or 33 parts. I'd never recommend that someone go with a completely non-standardized custom rifle to save a couple more inches. But is sounds like you already have a "51".