Paulf's Pictorial Guide To How I Made My Reising Run Great.
Posted 26 November 2007 - 05:13 PM
In another thread I mentioned that I had solved the woes associated with my Reising, member dalbert suggested I make a thread about what I did as to help other members who may be experiencing similar difficulties. So here it is!
A little history is needed before I get going. The Reising was my first SMG and I disregarded all the stories about broken firing pins, jams, and general unhappiness associated with the weapon. I was in love with that walnut stock, the .45 ACP is my favorite cartridge of all time, and most importantly (to me), U.S. Marines had actually marched off to war in the Pacific with these things! Even the fact that they had a truly terrible reputation with the Marines and were almost universally hated throughout the Corps couldn't put me off. It was in my price range, I liked how it looked, and I just had to have one as my first MG.
My search began in earnest and I soon located a nice piece that had been a PD gun in Pennsylvania. It looked very pretty and the price was right, in fact, I got it for a song. It only came with one magazine but that wasn't something I was worried about at the time, I should mention the one magazine was a 12 rounder to boot. I should have known better, but I didn't. I bought it! I did all the paperwork, ordered Frank's excellent book on the Reising, then I began the long wait for my first ever machine gun!
I have my C&R license and lots of cool goodies have shown up at my door. But the day that box showed up and I cut the tape was just too cool for school, staring me in the face was an honest to God machine gun! I couldn't wait to get to the range. I already had 200 rounds of Winchester White Box ready to go. Come Saturday of that week I went to a little known sand pit with my new treasure. I loaded the magazine with its entire twelve rounds and........ proceeded to be very disappointed. Just like everyone had said, this thing was a serious jam-o-matic. I was really let down. My LONG awaited foray into the NFA world was a flop. And now it looked like I was stuck with a turd and had shot my entire wad on it. Things looked pretty bleak at this point.
And now we get to part where I tell you how I cured all this and have come to love what is a truly awesome piece of weaponry.
I'm going to start out with what turned out to be the major problem with this weapon then throw in a few little "tweaks" I have done that have paid off in spades. So, enough delays, on to the good stuff.
When I first got the weapon I mentioned it came with a single twelve round magazine. On occasion I could knock off a 12 round mag dump but mostly it was a 2-4 round burst before I had a feed jam. Every jam was the same. The round would be hung on the feed ramp. The nose of the bullet would appear to be driven into the top of the chamber. A slight pull rearward on the action bar, tip the barrel forward, the round would chamber, let the bolt slam home and you were rocking and rolling again. The weapon was giving me clues to the problem but I was too dense to listen.
In my opinion this performance totally sucked. I couldn't imagine being in combat with a weapon that acted like this. I (mistakenly) thought it was magazine trouble. I located three of the awesome Ken Christie mags and immediately experienced the EXACT same feed trouble I should mention at this point that the weapon is missing a fin out of the compensator so I knew that at some point in its life it must have been a runner. This should have been my second clue that I was on the wrong path. But I kept on down the wrong road. I tweaked magazine feedlips endlessly. That had no effect. I tried bullet profiles from every manufacturer out there, no dice. I polished the feed ramp until I could use it as a mirror, again, same type of jams. After every marathon session at my workbench where I was absolutely sure that this time I had found the solution, I would cycle the action by hand through 6 or 8 fully loaded 30 round magazines and it would always function perfectly. Then when it came time for live fire it would jam almost immediately! I should also mention here that I don't give up easily and am way too hard headed sometimes. A smarter person would have thrown in the towel by now!
Every jam looked like this. Regardless of what type of magazine was in the well at the time.
I struggled like this for months. My wife encouraged me to just send the stupid thing to someone who could make it run. Guys, sometimes you really should listen carefully to what your wife has to say, yes, even when it comes to your guns. But I was too damn stubborn and decided I was going to figure this out for myself.
I need to mention here that I had never strayed from the path of this being a magazine problem. I mean the original 20 rounders were known to be problematic right? That was why they had converted them to a 12 round configuration. How could it be anything other than a mag problem?
Well late one night while I sat at my reloading/gun cleaning bench I think Eugene Reising got tired of me cursing out his baby and stopped by personally to give me some guidance.
I mentioned earlier that I always hand cycled rounds with no trouble at all. Every time I hand cycled the rounds I rode the action bar home with my index finger. Every time the action was unencumbered by my finger at the range I would get a jam. I had a sudden flash of genius. Maybe I should try to emulate actual range conditions! I pulled the action bar all the way back, then quickly yanked my finger out and let the bolt slam home. Well look at that, the typical jam I saw every trip to the range! Now whenever it would jam like this at the range I would do the quick clearing method I described above, take tension off the bolt with the action bar, tip barrel down, go live again. This time I didn't. I decided to study this jam up close. Yes, that's right, for the hundreds of jams I had encountered, I had never given the action more than a cursory glance before clearing it. This time I did, and what I saw blew me away. Take a look.
At the tip of the red arrow you can see the firing pin is protruding from the bolt and keeping the base of the round from riding up any further into the bolt. I knew at this point that I had just made a major discovery in the effort to make this thing run reliably.
Let me take a minute here to give my very laymanistic explanation of what I think was happening. I am neither a gunsmith, nor an engineer, but I think I have a pretty good grasp of what was happening.
The bolt in the Reising is miniscule, it has very little mass. In fact, I think a Ruger 10/22 bolt may actually weigh more. As the Reising is a closed bolt subgun it needs a separate firing pin from the bolt so it may function reliably in semi-auto. The firing pin in the Reising is not designed as a free floating design and as such has a retaining spring fitted over it when it is home in the bolt.
So what does all this mean? Here is my best guess. As the bolt is extremely light it comes forward with a tremendous amount of velocity when propelled by the action spring attached to the action bar. When the bolt is riding home it hits the base of a cartridge in the magazine. This slows the bolt considerably. However, the firing pin is independent of the bolt and needs a good strong retaining spring to keep its inertia in check, otherwise it would fly forward and protrude out of the bolt face. See where I am going here? Over time springs get weak. The springs in this gun were over 60 years old. So my theory was that the weak firing pin retaining spring simply couldn't hold back the firing pin anymore, it protruded from the bolt face, and voila, jam city, just like in the photo above!
Now the very anti-climactic solution to all this. Nothing more than a new set of Wolff gun springs. Yep, new springs solved 85% of my problems. But there were still problems to be encountered. And I wanted this thing running 100%. So the story continues. Here are the "tweaks" I mentioned WAY back at the start of this story.
Now that I had the gun running really well I was doing 30 round mag dumps like ammo was free and the zombie hordes were running wild! Guess what happened next? Broken firing pins ahoy! Yep, they started breaking left and right. So I set out to cure this. I took my cue from another one of my favorite weapons. The Colt 1911 .45 ACP pistol. I knew that the 1911 used what is known as an "inertia" firing pin. An inertia firing pin is exactly what the name implies. It uses the inertia of its forward momentum to extend beyond the face of the bolt and impact the primer on the chambered round. When the firing pin actually initiates the firing sequence it is no longer in contact with the hammer.
As I am alway pulling my weapons down to their bare essentials I began noticing that the firing pin in my Reising would always be bent. Even though I had put a new, straight, pin in recently it would still be bent. One day I decided I was going to attempt to transform a pin into an inertia variety and see if :
a: It would reliably set off a round.
b: If the damn things would stop bending.
Well, I am now into the thousands of rounds on that same "experimental" pin and counting! I think the inertia pin concept works on the Reising!
Here is a picture of all it took. Notice the red arrow indicates the small difference in length from a NOS pin to the Inertia pin of my making.
When the firing pin is full length it ends up being sandwiched between that absolutelymassive hammer and the primer of the chambered round. After enough of this type of pounding the firing pin says "I give up!" and simply snaps at the weakest point, the very thin tip.
To make your own inertia pin simply file the base of the pin down bit by bit until the very tip of the firing pin is just barely recessed in the bolt face when the base of the pin is flush with the bolt base. If you do this correctly then it will be impossible for the firing pin to be in contact with both the hammer and the cartridge at the same time, it will be one or the other, but never both at the same time. This one modification has saved me so much hassle with the annoying broken firing pin in the middle of a range session. The ten minutes it takes will pay for itself in spades.
Another modification I have done that has worked really well is bolt polishing. Using a combination of super fine sandpapers I polished my bolt until I could see my face in it. The reason I did this is that the tolerances on this gun are absolutely super tight. So as soon as it started getting dirty I could tell. The first thing was a change in ROF, then I would get a stutter in the middle of a mag dump. The slightest bit of buildup anywhere seemed to cause a hiccup in performance. So on a whim I used sandpaper from 1000 on up until 2000 grit to progressively polish the bolt to a mirror finish. Guess what? Huge improvement! For all I know it is the miniscule loosening of tolerances involved with polishing that improved the performance of my Reising. But it DID help out a lot. The weapon tends to get crudded up relatively quickly due to what I consider a kind of loose chamber, allowing a lot of carbon back into the action. And relatively quickly is a subjective term. I can go between 600 and 700 rounds before I need to get in there and hose out the junk. Yeah I know, it will never compare to an UZI or an MP5 in terms of rounds between cleaning but I rarely go more than 400 to 500 rounds per range session so that is plenty for me!
Here is a pic of a NOS unpolished bolt on the left, and my current polished bolt on the right. Not the best picture but you get the idea.
And finally I wanted to show my PaulF issued maintentance kit. Items include:
1 roll paper towels
1 medium sized flat screwdriver
1 thumb tack for removing the action bar and action spring
1 can of Rem oil
1 can of brake cleaner
This is standard issue when I go to the range. I know a lot of you will cringe at the brake cleaner. Sorry, but that is what I like, and I know it works. When I can audibly notice the ROF decreasing I know it is time to field strip the weapon. Once field stripped I hose out the entire receiver with brake cleaner. I give everything a few minutes to dry then the only things I oil are the bolt and the rails on the action bar. And these things I do very sparingly! The bolt gets a mist coat that I spread around with my fingers. The action bar gets the leftovers from my fingers, just enough to make the rails gleam a bit. This is in stark contrast to my M16 which is literally dripping with oil when she runs. But for whatever reason the Reising, at least my Reising, likes to be run dry.
Well here we are, finally! My "short" post turned out to be a novel. I hope you all enjoyed it, and more importantly I hope it helps some folks out!
Posted 27 November 2007 - 07:57 AM
Edited by bm59collector, 27 November 2007 - 03:13 PM.
Posted 27 November 2007 - 02:09 PM
Posted 27 November 2007 - 09:05 PM
Excellent post! I know it will help me, and others surely will benefit as well. Thank you for going to the time to document all that.
Posted 03 December 2007 - 06:11 PM
Posted 08 December 2007 - 07:04 AM
Posted 17 October 2008 - 07:28 AM
Posted 17 October 2008 - 05:34 PM
Posted 01 July 2018 - 07:30 AM
This is some good info to read while waiting for your Resing
Posted 08 November 2019 - 09:42 PM
Just shy of 12 years since I posted my original Reising thread.
I still own this little beast and it still makes its voice heard 77 years after coming off the assembly line.
My low tech firing pin fix is still very functional 12 years later. I am STILL on the same pin that I showed in the original post. This solution works, not a single broken or bent pin in all this time. And despite the age of this thing it has not been coddled, it has been used and abused.
I have put thousands of rounds through the old girl. All of them have been reloads, I couldn't tell you the last time factory ammo went through my gun. It absolutely loves 200 and 230 grain plated bullets pushed by Alliant Bullseye, Win 231,Win AutoComp, Ramshot True Blue, and Alliant Unique. It has digested them all and not complained a bit.
I think the Wolff springs are starting to get tired, but honestly who can blame them??? 12 Years of brutal full auto fire is a great testament to what a good job Wolff did when they put these things out there. Looking on their website I can't see Reising springs available any longer. But the set they sold me made my little subgun rock and roll. Maybe someone reading this knows where to get replacement springs????
My machine gun fever has quieted down but I do still enjoy the occasional backyard range trip to go rat-a-tat-tat. See the video below where I have one of my old school FTF's at :58 seconds. Then I do a proper function check.
Thanks to everyone who has followed these many years and let's keep these pieces of history alive a little longer.
My neighbors must love me.
EDIT: I couldn't find a way to embed this video so just click on the link above to see some gratuitous Reising footage taken from my GoPro.
Posted 14 November 2019 - 12:32 AM
Thank you for this Paul. I had the same problems of incomplete feeding and broken firing pin tips. By following your instructions on the firing pin I have gotten my Reising mostly running. I think that I need to do the bolt polishing next.
Posted 10 August 2020 - 04:42 PM
Thank you Paul for the information about the modification. I was a bit nervous about the mod but it worked out great.. though I had one snafu.
I have an older (3 digit S/N) Reising Model 50. I started to do the modification and when I checked out the fit.. I realized the firing pin had the retaining pin guide path milled too far back. Hence the hammer would never be able to hit the firing pin once I complete the mod, since it would be recessed. I had to take curve file and file down the channel so that it would allow the rear of the firing ping to stick out the proper distance so the hammer could strike it. Since I only recently got the Reising, I have no idea if the pin is a new aftermarket one or the original. (The finish on my Reising is beautiful and nearly looks new).
Any case I thought to point that out to people to look out for that. So far I was able to give it a test run and it worked flawlessly.
** This post should deserve a pin.. this mod is wonderful.
Edited by Ryo, 10 August 2020 - 04:43 PM.
Posted 06 November 2020 - 04:43 PM
Posted 15 November 2020 - 04:04 PM
Posted 28 February 2021 - 06:49 PM
I heard of firing pin problems and feeding problems back 25 plus years ago when I first purchased my Reising M50. Recently I took my M50 out of the closet and noticed I had two extra new firing pins and a new set of springs that I purchased along with three 30 rd. mags way back when. After disassembly, I noticed the original firing pin was slightly bent. I completed the above firing pin mod, as it seemed so logical. I'm now eager to go out and shoot a gun I haven't fired in a long long time. Thanks again. I just wish I had read this years ago.
Posted 28 February 2021 - 10:31 PM
Well I have new firing pin and new spring. Now to drift out bolt pin that retains firing pin?? And hope I can put it back together. I do not see instructions on how to remove the pin
Just push in the back of the firing pin followed by pushing out the retaining pin. The firing pin and spring will then come right out the back. On mine, the retaining pin falls out after I push in the the firing pin. Assembly is simply the reverse - insert firing pin with spring on it, push in the back of the firing pin, then install the retaining pin.
Posted 02 March 2021 - 12:24 PM
Well I have new firing pin and new spring. Now to drift out bolt pin that retains firing pin?? And hope I can put it back together. I do not see instructions on how to remove the pin
Just take it apart.. it's not a complex system so as long as your remember where you got your parts out of, you should easily put it back together.
Posted 14 March 2021 - 08:26 PM
I made this firing pin mod and fired my M50 for the first time since the 90's. It fired each round without any problems. It was interesting to feel the gun shoot as it feels different than those guns I have fired recently. Again, it shot very accurate and without any failures.