Techinical Discussion of Follower Mod

[OldLincoln]

Here's what the other forum showed. The pic on the left shows the follower round completely flat and there is a gap at the top. The middle pic shows the follower round with the rim elevated to match the angle of the upper rounds and the top round has a gap. The right pic shows that with few rounds in a mag the doesn't have enough of a slant to affect the top round. We don't hear much about problems below round 3 for 7rd mags, so maybe there something to this.

For fun, I took apart my 7rd mag and inserted 7rds from the bottom without the spring or follower. With or without pressure from the bottom the rounds gap. Keep in mind the gap is not between the bullets - they will always gap because they are pointy, the gap is between the front of the cases. The lips place the top round more nose up than the lower rounds so I do not see how you can stop the gap. But does the gap cause the feed problem?

Scoundrel's point about shifting the fulcrum is a good thought. I wounder how it can affect a round sitting so far above and in front of the follower though. The pics below are of a 1911 mag but are they much different in slope that Kahr? Note the rim of the top round lines up with the nose of the bottom round.

So this is a mystery to me. I believe those who say it works, I simply don't understand how it's possible. Hmmm.... are chicken bones and bat wings involved?

[Scoundrel]

Instead of thinking in terms of force pushing upward or downward on the rounds, let's think instead in terms of something getting in the way.

Try gripping a rifle by the rear of the stock only, way at the back behind the trigger, and lifting the barrel upward.

Now do it again, but this time, put a 4x4 on your workbench with the end sticking out, and try to lift the 4x4 with the tip of the barrel.

Now put a foregrip on the rifle, or support the rifle with a hand under the front of the stock under the barrel, and try to lift that 4x4.

Imagine this on a smaller scale, with a 9mm round instead of a rifle. If you're only pushing up on the back half of the casing, and the nose gets caught on something, where is the incentive for that nose to push upward against whatever it is caught on?


Here's a photo from GB's thread:

[Replay13]

Problem, rounds nose diving when feeding by hand and also firing.

The only thing if your drawing is missing is the gap between the bullets, but you do have a good point. Also it does seems to make a difference if the mag spring is put in wrong with the pressure toward the back of the follower.

Starting with the known facts.
1. The follower only supports the bottom round in the stack.
2. There is increasing gap between the bullets as more is added.
3. The mag lips sets the angle of the round being loaded.
4. The slide pushes forward on the top edge of the round being chambered.
5. The less rounds in a mag the easier it is to feed. Less gap and less spring.
6. The way the slide has to push on the top of the round when feeding caused the nose dive, and the less support on the bullet the worse the problem.

Ok the questions are how well is the bottom round supported and does changing the angle of the bottom round decrease the gap between the rounds. Depending on the type of the mod.

First mod, how well is the bottom round supported same angle but more contact? I know I can load a round in both of my mags and push down the front of the the round and it nose dives in the mag (the back of the round stay up to the top touching the feed lips) and if I push down on the back of the round, the whole round goes down.... So I don't think the stock follower supports the bottom round as well as it should. Maybe someone with a modded follower can put in there input?

Second mod, changing the angle of the follower. The more the angle of the follower the more the angle of the bottom round and it decreases the gap between the rounds. The rounds angle when feeding will still be supported by the mag lips. Reports say its working good. With my mags, the angle of the follower is the same as the angle the feed lips.

With my mags, I only have a problem slingshoting the first or second round. There is less spring pressure and less gap on the bottom rounds in the mag and they feed good. I don't have any modded followers, but I did put a temporary spacer on the front of the follower to change the angle of the bottom round and then I could slingshot the first round of a full mag. Also there was less gap between the top two rounds with a full mag.

Just my thoughts.
James

[DKD]

All I can say is what I think is happenning and that the mag mod as illustrated by SCOUNDREL works. My modified P380 mags load/chamber easier except the top round still wants to hang up alittle half the time when using the dang slide stop method, however I can briskly sling shot and get them pesky Gold Dots to load that number six round.
By the way as the second, third, and fourth round (and so on...) come up to the to the feed ramp the gap angle does in fact get less as you proceed toward the last few rounds. All I will say is that the modification was working better than the stock configuration and I am pleased with the fix. Over the past few days I have spent hours loading and unloading, slide stop loading, hand sling shot racking and with four or five diffrent manufactures, AOL cartridge lengths, and nose configuarations and the result were repeatable and did get better. I'll leave the pontification & prognosticating the engineering experts...

[Scoundrel]

I have a startling confession to make:
I just checked, and NONE of my magazines have the follower mod illustrated in that picture from GB's thread.

I definitely remember DOING that mod, but now that I think about it, I believe I did that mod on a 7-round magazine that was having nose dive issues, and I ended up sending it back to Kahr and they sent me a 6-rounder in exchange.

So never mind about the slingshot mod. I am not qualified to discuss it. I apologize for the misinformation.


I HAVE done the "nose dive mod" to all of my magazines, rounding off that front corner to prevent the mag release catch from grabbing the follower.



I just slowly hand-racked all of the rounds out of 4 magazines, watching carefully as I did so. Here are some factual things to report:

1. I had no trouble hand racking, slowly. Every round fed without me having to push it. I rode the slide back down.

2. When the slide starts to move forward, the nose of the bullet tips downward until it touches the feed ramp.

3. Once the nose touches the feed ramp, THEN the bullet starts moving forward.

This nose movement effect in #2 and #3 is most pronounced on a full magazine. As the magazine empties, it happens less and less until I get to 3 rounds left, at which point it doesn't happen at all - the bullets just start sliding forward with no change in angle. This corresponds with what I see when I load a magazine - there is no gap until after the 3rd round.

::End of factual information::


::Begin speculation::

I wonder if that downward movement on the nose of the bullet is what actually causes the feed issues?

I don't think it can cause the nose dives, because in the ones I've seen, the nose of the bullet is actually UNDER the feed ramp, and I just don't see how a round that started out with the nose above the feed ramp could end up with the nose under it. It seems more likely that nose dives are created a little sooner - before the affected round even gets to the top of the stack. Maybe the back end gets lifted and the nose shifts forward and gets stuck under the ramp due to insufficient pressure because of the follower getting hung up on the mag release catch.

But, I _COULD_ see that downward movement causing a failure to fully return to battery. If a lot of the slide's energy is expended smacking the nose of the bullet against the ramp, and if there are any imperfections in how smooth the ramp is which could "catch" on the bullet, further bleeding off energy, there might not be enough energy left over to stuff the extractor into its groove and slide the round up into position while shoving the round into the chamber.

[CJB]

Getting in a little late.... DKD asked the correct question, which Old Lincoln correctly answered.

I'm more inclined to think the shape of the lips, their width, and taper... would effect the release of the upper round(s).

Also remember, the gun recoils, and the the round may move forward....

When the bottom of the breech face strikes the top of the rim, feeding a round, we're at the mercy (to a point) of friction, causing/allowing the cartridge to rise up the breech face into position. Shaved brass anyone?

The same bevel that allows easy first round positioning, with an open magazine, is the same bevel that could be causing nosedives, as the breechface is touching the case at a slightly (ever so...) point. The bottom of the case, where it touches the round under it, becomes the fulcrum point in that scenario, and possibly we nose over.

Let me also introduce a new word to the discussion - bounce. Might there be bounce when it noses over? Could be. Could be it bounces down then up again.

I'm sure that Kahr has, or has commissioned, high frame rate studies of the feeding. They know things we could only guess at.

Something else to consider - the SAME basic configuration works in the P9, and the TP9, each with equal or greater round capacity than the PM9/CM9, yet the PM/CM seems to have most of the issues. High cyclic rate? Very well could be. Heavier spring at quite nearly solid compression at full stroke...may be something to consider.

[OldLincoln]

I'm certain my stronger recoil spring helped the feed for my 147gn HST rounds. They hung on the ramp before and with strong springs they may pause but give way and feed. This with setting the slide to a stop with the round nose touching the ramp then letting go. I hate to say it but I recommend everybody get the Wolff strong recoil spring.

There was some discussion about why the 8rd mag feeds well. The mag spring it it is much longer than the 7rd spring and some think that helps. Assuming longer is stronger while you're getting the recoil spring go ahead and get the +5 mag springs also and be done with it. Just hang onto the stock spring in case it doesn't help and you send it back. May as well send the stock spring.

[CJB]

I know that rise time from the mag is a critical thing in the Kahr design... its one weak point that I can see. With the slide velocity what it is, and the amount of feeding overtravel the slide "doesn't' have.. amazing it feeds as it does. So yah, a strong spring, a plus in my way of thinking.

[jocko]

buy some of wolffs 5% more strenght mag springs for kahrs. 5% doesn';t sound like much but it IMO helps to keep that top round poping up correctly,especialy going into those last few roounds, where the mag spring is at its weakest, who knows that 5% just might keep the gun running right. They dont hurt a thing and IMO make no difference in mag loading either..

[OldLincoln]

They dont hurt a thing and IMO make no difference in mag loading either..

Not supposed to hurt, but after a few cuts on my thumb from cramiong in that last round, I did smooth the underside of the lips just enough. I have and use the Ula loader most of the time but like pencils, I need some scattered around in order to find one when I need it.

[CJB]

Do like we used to on the Mac11-380 mags... smack 'em on yer leg as you press the round in!

[Deano]

...It seems more likely that nose dives are created a little sooner - before the affected round even gets to the top of the stack. Maybe the back end gets lifted and the nose shifts forward and gets stuck under the ramp due to insufficient pressure because of the follower getting hung up on the mag release catch.

I can with certainty say that the follower catching on the mag release was not the culprit in my nose dives. Why? Because it always happened after firing the first shot. The mag follower at that point is still way down the magazine, nowhere near the mag release catch. Also, sanding the follower to stop this catching did not solve the nosedive problem

Clearly in my mags, the top round of a full magazine is tipped upward at the same angle as the upper lip of the metal portion of the magazine. This round never jammed for me using the slide release or slingshotting. Once the top round is chambered, the next round never assumed this same angle. I would guess it is supposed to, but it never did until the mag got down to 3 or 4 rounds in it. Instead the second round was laying perfectly flat.

The slingshot follower mod helped improve this angle, but it still does not achieve the same angle as that of the first round or the follower until the mag starts to empty out. This is what perplexes me. Why is round 2 and 3 presenting at such a flat angle? It has to be because it is sliding forward about 3/16th of an inch, but you would still think the angle of the follower would be transmitted up the column of bullets to the top round. Part of me wants to do a test on the spring by cutting off 1/2 of the last coil at the bottom of the magazine so that the pressure point of the spring on the baseplate is at the front instead of the back. Would this keep the tip of the follower up better? I don't know, but I may try it on one of my springs for the good of mankind.

[Scoundrel]

Part of me wants to do a test on the spring by cutting off 1/2 of the last coil at the bottom of the magazine so that the pressure point of the spring on the baseplate is at the front instead of the back. Would this keep the tip of the follower up better? I don't know, but I may try it on one of my springs for the good of mankind.

Did you try just rotating the spring 180 degrees? Some folks have reported that their spring was installed backward, changing the angle of the pressure, and that simply reversing the spring solved all of their feed issues. There are pictures on this forum somewhere of spring orientation. If you can't find them, let me know and I will look, or take my mag apart and take pictures.

Clarification: Rotate the spring 1/2 turn like a drill bit turns, not flipping it end over end.

[Deano]

Did you try just rotating the spring 180 degrees? Some folks have reported that their spring was installed backward, changing the angle of the pressure, and that simply reversing the spring solved all of their feed issues. There are pictures on this forum somewhere of spring orientation. If you can't find them, let me know and I will look, or take my mag apart and take pictures.

Clarification: Rotate the spring 1/2 turn like a drill bit turns, not flipping it end over end.

My spring was installed correctly

[muggsy]

My Philosophy is if it ain't broke don't fix it and if the fix works don't question it. It has seen me through a lot of years. I'm also starting to adopt the philosophy of, "Shoot it like you stole it".