Help me guess spring rates for 9mm w/ ultradot

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Help me guess spring rates for 9mm w/ ultradot

Post by Merick on Mon 2 Jan - 20:12

I'd appreciate some input on spring rates for my project gun.  I flip the lower between a advantage arms 22 conversion and a 9mm top end.  The 22 unit was always fiddly, and now that I have added a ultra-dot to the 9mm slide, that has become fiddly too.

Step one; factory springs ?lbs
22 fiddly
9mm no ejection

Step two; wolff 19lb mainspring, 11lb recoil
22 less fiddly, mainly magazine issues.
9mm  100% stove pipe decent rings, 50% ultradot rings

Step 3; wolff 19lb mainspring, gun store 'very weak' used drawer recoil spring
22 unchanged
9mm 25% stovepipe

Step three; to be determined

I'm guessing I need a wolf 7 and 9 recoil springs, and perhaps a lighter mainspring? 
Thanks

Merick

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Join date : 2015-08-13
Location : Hutchinson Kansas

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by rreid on Mon 2 Jan - 20:25

I tried a 17# mainspring when I first got my Nelson conversion, but there were a lot of light hits. I get 100% with a 19# now. You might be able to get away with an 18#. I'm not sure what Advantage uses, but there are other recoil springs available for marvel and Nelson. I use an 8# in mine for standard velocity.

rreid

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by dronning on Mon 2 Jan - 20:38

On my 9mm I'm running a 19lb mainspring, the large radius firing pin stop and an 8lb recoil spring.  Had to tune both the mags and the extractor a little.

I'm running a frame mount optic.

- Dave

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by LenV on Tue 3 Jan - 7:51

Is the 9 an RO? Did you change the mainspring housing? Did you consider upping the load in the 9? If that was asked of me the answer to all questions would have been "yes". I had an RO. to make it reliable with a dot on the rail I had to get rid of the ILS and up the load (improved accuracy at same time). Now I use a 12# recoil spring and 18# mainspring. I have a Nelson coming but expect no problems with the 18# mainspring.

Len

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by Merick on Tue 3 Jan - 9:51

Not a RO, a rock island that I futz around on, but it looks more like a RO every day, to me anyhow.  I did have a load that worked (heretofore unmentioned) but leading was bad and I blew out a case (!).  So for now I am going to lower variables and use white box.

I think that the 19# mainspring will stay for now, 18 might be better if I fall into one.  But I will order a 7 &9 recoil springs, as well as an oversize firing pin stop.  The firing pin stop I have is pretty sloppy and that might be causing more problems that I thought.

Merick

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Location : Hutchinson Kansas

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by Jon Eulette on Tue 3 Jan - 10:02

Merick, are you shooting irons or optic? If optic what mount; slide or frame?
Using a recoil spring below 10# and accuracy will normally drop beyond 25 yds. Recoil spring keeps slide in battery. 10# is normally for an accurized 9mm that has match fit barrel to slow the slide down. 12-14# more common for factory ball ammo with no optic on slide. Assuming you are using completely stock sloppy loose slide and barrel your pistol should function a mild load with a 10# spring easily!
Light springs on .38 specials still have same issues with light springs. You can go to light and lose your 50 yd accuracy.
Jon

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by Merick on Tue 3 Jan - 10:15

To be clear 9mm top end has a weaver rail, scope rings and and ultradot mounted to the slide.

Without those hangers on function was ok.

With them it would unlock but not eject with regular loads.

With 11# spring into stovepipe territory.

Merick

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Join date : 2015-08-13
Location : Hutchinson Kansas

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by Jon Eulette on Tue 3 Jan - 10:29

Check extractor tension. If too loose will stovepipe. What load?
Jon

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by Merick on Wed 4 Jan - 22:02

Extractor tension is ok I think, but the firing pin stop is loose enough for the extractor to clock.  Load is winchester white box 115 fmj as a base line.  Once that works I'll move on to my hand loads.

Merick

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Re: Help me guess spring rates for 9mm w/ ultradot

Post by Merick on Wed 11 Jan - 20:23

Update; 9lb recoil and 19lb mainspring, new firing pin stop, slide mounted ultra-dot and factory 9mm ball ammo functions nicely.

Merick

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Location : Hutchinson Kansas

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Re: Help me guess spring rates for 9mm w/ ultradot

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