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marcin c

FTF - smiley on the bullet

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Hi,

I recently received 2 identical .40 Limited (standard) guns from a top custom shop. Both by now have around 2.5K each.

STI frame and slide, KKM barrel, SVI steel grip.

From the beginning experience FTF's, the round enters the chamber half way and stops at cca 30 degree. Push on slide and the round eters the chamber (usually). Replaced the Aftec on one of the guns with regular (tuned) STI extractor, that helped somewhat. Experimented with different AOL's, recoil spring weight (although I don't really want to get over 13 pounds) but FTF's still occur (although less frequently).

The only magazines I can use right now are original STI mags, as nothing else (even SVI!) magazines will not fully enter the very tight grip (perhaps need to do some filing inside). Same magazines will feed normally from my old plain Edge. Mags have Grams kits inside.

Now started shooting softer (epoxy coated lead) bullets and noticed that every chambered bullet (only if shooting, not manually releasing the slide) has an imprint from the lower half of the chamber's edge (where it meets the ramp) - see photo. That explains the ocasional "stutter" I get while shooting.

Also, when I release the slide slowly, all the bullets will stop on the ramp (I know, they're supposed to feed when slide moves forcefully, but with my other guns that was not a problem). Guns are tuned, everything is polished and were tested by the gunsmith prior to shipping.

Sending them back to US from Europe is not really an option. Any ideas what may be the cause of FTF's? Could it be the STI magazines sitting too low in SVI steel grip?

post-15548-0-44253800-1308817455_thumb.j

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What OAL are you using? I load .40 to 1.200" Is there a sharp lip on the bottom of the chamber? It is kind of hard to diagnose without the gun in hand.

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I used to have smileys on the nose of soft moly bullets too. I traced it to the bottom of the feed ramp hitting the top round in the mag as the slide came back, not the bottom of the chamber as the slide went forward. At an OAL of 1.23 I got deep smileys and the occasional FTF as the bullet would hang up on the bottom of the ramp. At 1.95 I still get occasional smileys, but I don't get any FTF's. After a stage the live round in the chamber always has a light smiley.

Load a mag with dummy rounds and pull the slide back aggressively, but then don't chamber the round. Release the mag and check the first bullet. If you have a smiley it must have come from the bottom of the ramp, not the chamber. If that's your issue, try loading a bit shorter.

Good luck,

Aaron

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The mag catch cutouts are different from sti and the new svi grips . Do you have can you get a new sv mag to try?

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First: You will require SVI mags with the new SVI grips.

Second: I always had problems with molly bullets and KKM barrels. KKM is a great barrel IMO, the 40 barrels just don't seem to like mollies. I tried many different brands of mollies and always had FTF. Had smileys also.

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Moly's are sometimes too big for a standard throat. I have to open the throat up just a bit and add a small bevel to the headspace rim (like AET barrels).

I get smileys on my lead .45's. BUT, it's only when ejecting a loaded round. The round hits the ejection port on it's way out. Not everytime, but some of my ULSC rounds have it.

The FTF you mention, where the round stops at a 30* angle (3 pt jam?) can be caused by the extractor or the barrel feed ramp (chamber mouth). Look for brass coloring inside the hook cutout on the extractor. The circumfrance of the rim should not hit the inside of the hook cut out. You can also pull the extractor out and try to chamber a round. If it still hangs up look at adding a little more radius to the chamber mouth of the barrel. With ramped barrels you can get pretty aggressive without exposing too much (if any) of the case wall.

When you get one of the 3pt type jams, use a small punch and try to lever the extractor to the right (away from the case). If the slide goes forward and the round chambers, that is a good sign it's the extractor.

The last gun I built had an issue where the extractors tried (EGW and AFTEC) were too short. Not enough hook clearance to allow the case to cam up on the breach face. It showed up as an occasional 3pt jam.

Edited by want2race

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I radius the ramp and chamber like want2race said. It may be an extractor issue but I figure a little smoother entry into the chamber can't do anything but help.

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Thanks for the input!

You are right, the smiley may be from the bottom, not the top of the ramp.

Soft bulleted rounds, where I first noticed the smiley were 1.173 OAL. But my primary concern was the FTF's, which occur with alll sorts of OAL's. When I noticed smileys, I thought this may be a manifestation of some irregularity that contributes to FTF's.

There was definitely some extractor induced problem, as without the extractor rounds cycle better.

Yes, the magazines may be the problem. I have one SVI magazine that barely fits into this SVI grip. From that magazine, rounds seem to be feeding OK. Maybe its a difference in sitting height?

What if I open up the lips?

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