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Tuning SPS 170mm magazines


matt2ace

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I have 3 x 170mm SPS magazines, all with Bolen parts. One works flawlessly, never a problem with up to 29 rounds, even after being dropped multile times. The other two exhibit bullet dive even with a little as 20 rounds loaded. I have tuned both mags to match the dimensions of the working mag, but still cannot fix the bullet dive problem.

Does anyone have a solution to the bullet dive problem with SPS magazines that they are willing to share?

I have checked with a few of the better known mag tuners and none are interested in tuning SPS mags.

Is there is anyone offering tuning services for SPS magazines?

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Hello: I have not played with the SPS mags yet(I don't have any). You have to make sure the feed lips are correct and the bullet angle is correct. You also have to make sure the bullets are stacking inside the mag correctly to allow good feeding. It takes some time to get this all to work correctly. Each mag can be different in the way that all of these are working together. You have to measure the mags and slowly change one thing at a time and see what works. As I say "sometimes you have to pay for knowledge". Thanks, Eric

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  • 3 weeks later...

i have tuned just one of the SPS so far to hold 30rnds. the key to reliability is in the follower. like J said, install grams followers.

Drop in a grams kit on the problematic mags

Edited by RoryW
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i have tuned just one of the SPS so far to hold 30rnds. the key to reliability is in the follower. like J said, install grams followers.

Drop in a grams kit on the problematic mags

I agree with Roy the key is in the follower, but you need alsoto adapt the spring to support better the follower so the butter present itself with the noise up to the chamber. You can try to bend to the top the third/fourth turn of the spring. this procedure is better explaned on this great forum in the post spring.

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:surprise:

On any hi-cap magazine the mag it self has to have the proper curve under the first round

to hold the second and thrid round to support the first round, if this curve/shape isnt

right it doesnt make much differance which spring or follower you have in the mag you

are going to have a nose down problem.!!!

Jim/Pa

Sailors :devil::blink:

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