New Magazine Spring metrics

Remington 870 Repair and Gunsmithing.
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redgoat
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New Magazine Spring metrics

Post by redgoat » Sun May 29, 2016 2:12 am

When discussing the most desirable upgrades to an 870, the one item which seems to always make the list is the magazine spring.

I was swapping out the magazine follower in an almost-new Police Magnum 870 this morning and, due to the frequency of the topic, started wondering: How long are the various magazine springs and how much pressure do they exert? The discussions I've read never seem to quantify these, so my curiosity got the better of me. I had to find out.

Since I had the almost-new Police Magnum opened up, I grabbed its spring, one from a swap-out on a new Express, and a new Wolff XP spring I'd ordered from Brownell's. Since these were all three essentially new springs for a 4 shell magazine tube, the comparison should be "apples to apples."

First I measured the lengths. Here's a photo of the results:
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Next, I attempted to measure the amount of tension each of these three different springs exert. I've never attempted such a thing and so puzzled a few minutes before arriving at a procedure which hopefully yielded some meaningful measurements. I already had the barrel off the Police Magnum and its magazine tube cleared, so I decided to use it to conduct the experiment. I left the new stainless steel follower in its normal place at the breech end of the tube. Next, I put each spring into place and capped the muzzle end of the springs with the bright orange stock Remington follower, pressing straight downward on a food scale until the spring and leading follower were flush with the muzzle end (threaded end) of the tube. Then I slowly lifted the assembly to take the weight of the gun off the scale, hopefully capturing a reading which reflects close to the true amount of tension the spring was exerting. Then I added one, two, three, and finally four snap-cap shells, repeating the same process for each.

Are you still with me now?

Here are the results:

Express spring: 0 shells -- 17 ounces, 1 shell -- 37 ounces, 2 shells -- 53 ounces, 3 shells -- 69 ounces, 4 shells -- 85 ounces
Wolff Spring: 0 shells -- 33 ounces, 1 shell -- 50 ounces, 2 shells -- 67 ounces, 3 shells -- 85 ounces, 4 shells -- 98 ounces
Police spring: 0 shells -- 50 ounces, 1 shell -- 52 ounces, 2 shells -- 66 ounces, 3 shells -- 82 ounces, 4 shells -- 84 ounces

So, what did we learn, boys and girls?

1. The Express spring is definitely a bit "weaker" than the Wolff or Police Magnum spring, so if a "stronger" magazine spring is desirable, the upgrade to an aftermarket or Remington Police spring is probably worthwhile.
2. The longer spring is not necessarily the "strongest" spring. The slightly shorter Wolff spring caught up with and surpassed the Police spring above the "two shells" level.
3. It is darn hard to measure spring tension accurately without some more specialized setup. If I can figure out a way to set it up without risking breakage of the food scale, I think some sort of horizontal or "top down" positioning would yield a more accurate result since that would take the weight of the gun out of the equation altogether. Hmmmmmm.
4. For the stock Express spring and aftermarket Wolff spring, each shell seemed to have added about 16 ounces of tension. I was surprised at this, it doesn't "feel" like that much when doing an actual magazine load.
5. For the most consistent "feel" throughout the entire compression cycle, the Police spring seems to be the winner. I'm not certain if that's a desirable trait or not, but there ya go. It might be that a linear proportional increase in tension per shell is more desirable from the reliability standpoint. You pay your own money and make your own choice.

It was also interesting to note that the Police spring seemed to have a couple of "flat spots" in tension at the beginning and at the end of the compression cycle, whereas the stock Express spring and the Wolff XP spring both seemed to increase in tension proportionally throughout the compression cycle.

DISCLAIMER: I will add that I cannot say for certain that my procedure is not flawed, so take these spring tension measurements for what they are: my best attempt to get a correct measurement. However, I would presume that the relative changes in tension (about 16 ounces per shell for the Express and Wolff) is close to correct. Also keep in mind that these measurements are from a single example of each spring type. Other examples of the same springs would probably yield at least slightly different results.

Just a bit of food for thought and some small factoids for your 870 trivia database. Enjoy!

BurstBarrel
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Re: New Magazine Spring metrics

Post by BurstBarrel » Sun May 29, 2016 9:47 am

Very interesting test. My shotguns have always been bird and clay guns with a plug so they never have more than two in the magazine and that I know of have never had a spring problem.

Across the board on firearms I'm not on the spring bandwagon of going extra power or lighter unless there is real problem to fix.
:lol:
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DIY Gunsmith, Handloader and 870 Owner

redgoat
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Re: New Magazine Spring metrics

Post by redgoat » Sun May 29, 2016 5:11 pm

Across the board on firearms I'm not on the spring bandwagon...
Agreed. One should know what the effect will be and why it's needed before making the swap. The reason for the post is to try to quantify the length and tension so that others can make informed choices rather than just blindly deciding "Oh, I need a 'stronger' magazine spring. I'm going to order and install spring X because that's the one I saw recommended in an Internet post or article."

That being said, I am an incurable tinkerer and sometimes (way too often) my curiosity gets the best of me. I have made more than my fair share of parts swaps only to find that the original stock part was doing its job "better" or that the replacement part was really a piece of junk "just made to sell." On occasion I have found parts that yield what I feel are improvement in function, reliability, or aesthetics. Sometimes more than one. But always put function and reliability over aesthetics. Trying things is one of the methods we use to learn.

Hopefully, the collective wisdom and information sharing on this forum will help all of us to select those parts which actually present some form of improvement, even if only in the highly personal and subjective area of aesthetics.

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Vitaly
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Re: New Magazine Spring metrics

Post by Vitaly » Sun May 29, 2016 7:22 pm

I also highly recommend checking Nordic Components magazine springs. Most of the competition shooters use them, especially for shotguns with long magazine extensions (+7, +8 rounds). They are 45" long and need to be cut to proper length.
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redgoat
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Re: New Magazine Spring metrics

Post by redgoat » Sat Jun 04, 2016 3:18 pm

@Vitaly: The next time that I order some parts I will get a couple of the Nordic springs and will add its information to this post.

Just so that I keep my comparisons balanced, what length do you recommend cutting the Nordic spring to for the standard 4 shell Remington 870 magazine tube?

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