Action Spring Length in Auto-5 Clones

Discussion in 'Browning Auto A-5' started by Hcompton79, May 20, 2019.

  1. Hcompton79

    Hcompton79 .22LR

    I have come across your forum here, and think that you all seem to be the foremost experts on Browning's long recoil shotguns.

    I have owned a Belgian Sweet 16 Auto-5 for a number of years and it has been nothing but reliable after I replaced the action and recoil springs in it when I acquired it. However, I have been looking for a 12 gauge Browning long recoil shotgun due to the easier availability of ammo. I recently found and purchased a Savage 720 shotgun, as this is basically a licensed copy of the Auto-5 and seems to command less of a premium than a Belgian gun while being almost functionally identical. A real bargain if you ask me.

    Now I hope you all won't crucify me for talking about a non-Browning produced gun, but I have a functional question about my Savage.

    As received, the recoil spring appeared to have taken a significant set, as it was much shorter than the one in my Sweet-16. So I ordered a new set of recoil and action springs for this gun from Midwest Gun Works, and I read that the springs should interchange with an Auto-5.

    Now, upon test firing with new springs, I found that the gun would cycle light loads (1 oz and 1 1/8 oz target loads) on the heavy friction ring setup. Also, I felt very easy to retract the bolt when the hammer was cocked.

    Thinking that my new action spring may have broken, I pulled the stock and checked it, and found that it was not broken, but it was actually about an inch shorter than its replacement. I put the old action spring back and found that the bolt offered about the resistance that I expected when the bolt was pulled back with the hammer cocked.

    Now, my question is for anyone who may be familiar with these guns. Are the action springs really interchangeable between the Auto-5 and Savage 720? Also, would this cause my issue of the gun cycling light loads on the heavy setting?
  2. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    The parts are suppose to change between a5 and 720 from what I have read. Some parts will swap with model 11. My model 11 has some a5 parts and functions ok. As to what parts will work and not is a good guess unless you have 720 parts available to compare. I have had some issues with springs from MWG. I shoot 1 oz loads and all mine are set up for light loads. I have no problems. The spring rate may be different. Who knows. The 720 spring should be available. If it functions and ejects ok and the recoil is the same, then who cares. Shoot and enjoy.
    My model 11 has a buffer pad in the rear of receiver that provides an impact cushion. Not sure if 720 has one or not. I would think it would be important to have it there, but when I got it from my uncle. He had fired for 20 years and had no clue there was suppose to be one there. I actually have a 12 mag that will fire 7/8 oz target loads with no issues.
  3. Hcompton79

    Hcompton79 .22LR

    I went and test fired it again with the original 720 action spring in place, this time it cycled the 1 1/8 oz loads fine on the heavy load setting but left the 1 oz loads in the chamber after firing.

    My concern is that if it cycles light loads fine on the heavy friction setup, then when I go to use some heavy 1 1/4 oz bismuth loads for duck hunting, it may put unnecessary wear on the gun.

    My Savage 720 does not have a buffer in the back of the receiver as a Remington model 11 does, it has the same cutout for the firing pin as does a Belgian Auto-5.
  4. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    Well without having some expensive test equipment I doubt your gonna get a definite answer, unless someone has one that you can measure. I would guess that the spring rates are different. Checked numrich and they list different part numbers, an A and a B between the 720 and model 11. I know my a5 mag will not cycle 1 1/8 oz. I replaced the recoil spring with light 12 spring and it will cycle 7/8 oz. I checked MWG and they list different numbers for light 12 and mag spring. My old 12 mag spring was one spring inside of another, so 2 springs. The new 12 mag spring that you can order today is one spring. I don’t think I would fire the heavy loads with that spring. It’s probably going to let the bolt slam into the back of receiver. You may wanna try a 12 mag spring. Start with light loads and work from there. I had a small spring made for my Zoli, that’s no longer produced, and parts are not available for. It was for the ejector. Cost me about 100 bucks, but was worth it cause it’s one of my favorite shooters.
  5. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    You may wanna try shotgun world also if you don’t get a reply from someone that owns a720 on here.
  6. Hcompton79

    Hcompton79 .22LR

  7. Hcompton79

    Hcompton79 .22LR

    Well, in the effort towards getting to the bottom of this, I employed some methods of primitive science. I build a simple spring compression tester using a couple of rods of different diameters mounted on a 2x4 and a 5lb weight for each.

    In terms of the recoil springs:

    The original from the Savage had 19 coils and the wire diameter was .120". The uncompressed length was 7 5/8" and the compressed length was 7 1/8".

    The new standard 12 spring from MGW had 19 coils and the wire diameter was .120". The uncompressed length was 9" and the compressed length was 8 1/2"

    According to the Browning Auto-5 service manual, the standard 12 gauge recoil spring free length is 9.25" but since spring rate can vary based on steel composition, this may not be a valid comparison to the spring from MGW. However, based on the dimensional similarity between the MGW and original savage spring and the rate of compression seems to be similar, the springs would seem interchangeable although my original seems to have taken quite a set.

    As to the action springs:

    The original from the Savage has 87 coils and the wire diameter was .042". The uncompressed length was 13 1/2" and the compressed length was 9 3/4".

    The original spring from my 16ga Auto-5 has 81 coils and the wire diameter was .043". The uncompressed length was 12 1/2" and the compressed length was 9 5/8".

    The new spring from MGW was 77 coils and has a wire diameter of .042". The uncompressed length was 12 7/8" and the compressed length was 9 1/4".

    Again, the Auto-5 service manual the action spring length which is said to be the same for all models is 13.25". From the examples I have to compare it certainly seems to be different. I have contacted a few gun parts sellers to see if they can tell me the uncompressed spring length of a new 720 spring so I will report back if I find out something more.
  8. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    Seems like they would be about the same by your measurements, however, I always like the ammo to be the final word. If your gun will cycle the light loads on the heavy setting I would question the spring. And I was only talking about the recoil spring. The action springs are all the same. I ordered a 16 gauge spring from MWG and it would not fit. Everyone else list the 16/20 as the same recoil spring. Pulled one off my light 20 and it fit the 16. Tried the new 16 spring on the 20 and it fit. I called MWG and they said” the part number is different from browning, you can send it back and we will refund your money. Some things about the a5 can not be explained, may be that way with the 720.
  9. Rudolph31

    Rudolph31 .30-06

    It could also be the bronze friction piece; they wear out too.
  10. Hcompton79

    Hcompton79 .22LR

    How does one tell when the friction piece is worn out? Mine still has the protruding ridges sharply figured, they do not look worn, nor is it loose on the magazine tube.
  11. Rudolph31

    Rudolph31 .30-06

    Good question. But you’ve replaced your springs, there’s nothing left.

    You might try adding a magnum friction piece with two additional steel rings. Looks like MGW only sells them as part of a “rebuild kit” so look elsewhere.
  12. Hcompton79

    Hcompton79 .22LR

    I got a reply from one parts retailer saying that the length for a new production Savage 720 action spring is 12 7/8". So I think that the two parts are as close to interchangeable as you are going to get in today's market.

    I may buy a new friction brake and spring, but I have also heard that you can improve the braking action by roughing up the surface of the magazine tube with 300 grit sandpaper. Mine feels very smooth so I may try this first.
  13. Rudolph31

    Rudolph31 .30-06

    That’s not something I would do.
    Ranger6 likes this.
  14. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    I don’t know if I would recommend that. Is the new spring available? Then buy that and keep it like it’s suppose to be. You may cause more issues then it’s worth. If your not willing to spend money to do it right, then not worth doing in my book. You may open a can of worms, if you don’t believe me, read through my post on the speed load conversion. Huge undertaking, it cost me more then the gun will ever bring on the market, and lots of time. Not saying it can’t be done, cause with the time and effort and money anything can be done. Mine functions correctly but didn’t think I would ever get there.
    Last edited: May 21, 2019
  15. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    Damn started typing a reply about an hour ago and posted. The page refreshed and I seen your post Rudolph31.
  16. Hcompton79

    Hcompton79 .22LR

    Alright, I will hold off on that approach. The new action spring for the Savage 720 is available, but as far as I can tell based on the data provided above is no different than that being offered for the Brownings. Even if there was an original production difference, it seems that everyone is selling dimensional similar parts for all the long recoil shotguns.

    Now, I do have another question. How much does the friction spring that wraps around the bronze friction piece contribute to the braking force? I really don't think my friction piece is worn out but I have noticed that my friction spring has about a 3/16" gap when it is not on the friction piece, and I found this photo which shows a new part with practically no gap:
    https://www.ebay.com/itm/Remington-...627366?hash=item34096fe4a6:g:UawAAOSwAPxcxM3r

    So, this part may be worn?
  17. Ranger6

    Ranger6 Administrator Staff Member Administrator Global Moderator Forum Moderator

    Ok we’re talking a few bucks here. Order the new(right) spring and friction pieces. Put them on and test it out. Don’t try to re-create the wheel. If the parts aren’t available, then find a work around. Just my 2 cents

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