2011 mag feed lip tuning , , ,

[Whoops!]

So, I was tuning my feed lips tonight and hand cycling the rounds through the gun with small increment adjustments and then live firing them. I noticed that the width for the feed lips is not universal for optimum feeding among different manufacturers and have not seen this mentioned before.

In my experience, the point of diminishing return for feed lip width is .350 inches on a old version Strayer Voigt Mag. On two STI mags, it is .365. After these widths and in the open gun I was using for testing, feeding does not seem to be any smoother and thus the gun will most likely be more prone to a failure to feed with the bullet against the top of the hood as opposed to nosediving. These are the measurements at the rear of the feed lips. The front measurement is .005 wider.

These widths improved the function in the way I wanted them to. In a 2011 open gun which would nosedive with anything less than a 9 lbs spring now functions with all of these mags down to a 7 pounder and I had no failures to feed with the STI lips as far as .374 inches apart. About 200 rounds were used for testing

My main point here is, if you have different mag manufacturers, don't think one feed lip spec will do it. It's a trial and error process and I believe it depends on : your model of barrel, your extractor, your magazine spec, and your ammo spec with regard to oal and bullet shape.

These feed lip specs are for 1.25 OAL Hornady 121 gr HAPs in Starline .38 TJ brass with an Aftec extractor and a Schuemann AET barrel

[mike cyrwus]

If you want to take it one step further, how your barrel was fitted to the frame is also a variable, how it was ramped, polished.

Its not as simple as saying those specs, and those parts, with those bullets are optimum. ymmv.

[Ace38super]

The feed lips on an SVI mag are nothing like a STI. I am suprised you could even bend them. I have 2 SVI 170s and a 140 and have never needed to mess with the feed lips. On STI mags you could get an out of spec mag caused by dropping the mag but even my tunde STI mags have some variation in the feed lips. .356 is a good ball park but they should work fine anywhere close to that. The Dawson mag tuning package is a good investment of $99 to keep your STI mags in tune.

[Mat Price]

The Dawson mag tuning package is a good investment of $99 to keep your STI mags in tune.

Are the instructions in the package easy to follow ?

[Aircooled6racer]

Hello: A good standard width for the feed lips for 9mm is 0.357" wide front and back. The big thing to remember is the angle of the feed lips. If the angle is good almost any feed lip width will work. I have some SVI mags with very narrow feed lips and some others with the 0.357" width. They all feed just fine. They also work well for 38 SC. Thanks, Eric

[Rambo]

The Dawson mag tuning package is a good investment of $99 to keep your STI mags in tune.

Are the instructions in the package easy to follow ?

Comes with a DVD that demonstrates... I'm glad I got it... Though I must say Dave sure makes it look insanely easy

[Whoops!]

Feeding ok is a lot different from feeding perfect in my experience. Anything below .365 on the STI mags added friction on the feed and therefore would be detrimental as far as I can tell with the AET barrel. The gun would function with certain widths below what I said with the lighter weight recoil springs, but for optimum feeding in those conditions mentioned, those are the specs I say.

The AET barrels are all ramped the same, which is to say, different from every other barrel on the market.

If you have an AET barrel, and you're looking for super smooth feeding, I think you'll be happy with the specs above.

Aircooled, can you explain the angle facet to me and how to appropriately measure the angle?

Edited February 14, 2012 by Whoops!