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Coharie CA94 - Failure To Eject (FTE) Troubleshooting Tips

Posted: June 04, 2009 | Last Updated: September 19, 2009

Below is an example of a Failure To Eject (FTE) which shows the spent casing (top) jammed back into the chamber area with the newly stripped round from the magazine (bottom) trying to chamber.

This results when the spent casing is pulled out of the chamber by the bolt face & extractor, but not ejected completely out of the ejection port or because it fell off the bolt face (loose tension) before the ejector could do its job.

My suggestions for eliminating this issue are as follows:

CA ejector. Replace it with the latest H&K design.
CA extractor. Make sure the edge is not rounded or the circumference unmatched to bolt head face cut circumference. Replace it if you suspect an issue, most are crap.
Bolt group not cycling freely. Run the bolt group by hand and check for burrs or any reduction of movement during the cycling process. Find and remove obstruction.
Bolt head gap too low. This causes the lock time to increase and the rearward movement of the bolt group to decrease. Make sure your bolt head gap is in spec. Be sure to drop the bolt group with the gun facing down and pull the trigger before each measurement. Measure 3 times making sure you get the same reading on your feeler gauges, then compare to the manual. Below is the page from the armorer's manual concerning bolt head gap.
Casing falling off bolt head face. Can be due to weak extractor or out of spec CA bolt head face. Take the bolt head (face up) and put a casing in under the extractor then clamp the extractor against the bolt head with a pair of vise grips (put some kind of protective material between to prevent scratching) then shake the bolt head. The casing should not wobble or fall out. If it does, the face is out of spec and no matter how strong of extractor spring you will not get consistent extraction tension which can cause Failure to Extract (FTX) or FTE. The illustration below shows the problem with an out of spec CA bolt head face cut.

Numbers not adding up!

Shattered Mind (username) on www.hkpro.com suggested that the bolt face cut is so out of spec that it is likely that a 10mm CA bolt head was assembled into the gun by accident. Since the reading is .434" and the .40S&W/10mm casing rim is .424" this would make sense. Also, viper5194 on the same forum had this to say; "I read somewhere CA uses the same NF461 bolt for 9mm and .40, just has a diff. face dimension with no other markings. So it could be the wrong bolt as stated."

75bronco (username) on www.hkpro.com (also associated with Rim County Manufacturing) posted: .40 boltheads are night and day from 9mm... We have seen numerous guns come in with bolt heads that look like 9mm but have .40 bolt face diameters. Also the extractor pocket was dremilled out to allow the extractor to move farther in. This was so the extractor could carry out an empty 9mm case.

CHECK YOUR BOLT FACE BEFORE ASSUMING IT'S THE EXTRACTOR OR EXTRACTOR SPRING!

If your bolt head face measures .434-.435" then you have the wrong cut for a 9mm bolt head. You will need to replace it. The video below shows the difference between a miss-cut and a new RIM bolt head.

Supposed email from Coharie Arms that has some bearing on the bolt face issue and might confirm that their 9mm bolt heads are way oversized and not a mix up with a 40S&W/10mm face like some thought. http://www.ar15.com/forums/topic.html?b=6&f=9&t=290753&page=1&#2556640

Sent: Sat 9/19/09 12:15 PM
It is apparent you do not know what a 40 cal bolt head is or looks like and in fact you DO NOT HAVE ONE IN YOUR GUN
the 9mm head used full rollers and the ejector comes in from the side
http://www.hkparts.net/shop/pc/viewPrd.asp?idproduct=131&idcategory=90

The 40 cal uses half rollers and the ejector comes in from the side
http://www.hkparts.net/shop/pc/viewPrd.asp?idproduct=451&idcategory=7

A 9mm bolt head and 40 cal can not be mixed up neither will fit in the respective guns and even CLOSE the action PERIOD. what you have is OUR 9mm bolt made to our 9mm specs you need to stop reading all the BULLSHIT On hkpro and then think you are a pro

Look at the pictures in the links and you will see you are WRONG

The video below is to give you an idea of what a "sprung" extractor spring looks like so you can replace it ASAP (buy a bunch of these!) and to give some kind of comparison of the tension I have on the CA bolt head and the H&K bolt head with new .223 extractor springs. I wish I'd had some device at home to measure pressure when knocking the casings loose, but did not. I used a Ty-Wrap as an unscientific attempt to show the difference. I can only say that it "feels" like a 3X increase in tension on the H&K bolt head.
Ejector riding too low. Check that ejector is not riding low in bolt head. It should be almost touching the bottom of the bolt head when you cycle it back by hand. Even if ejector looks good, a sloping trigger housing can mess the timing up and not be noticeable during this check. An ejector riding too low looks like the blue rectangle in this picture. It should be at least 1/2 again closer to the bolt head than shown in the image.
Trigger housing needs to be parallel with receiver and tight against it without shimming. Make sure a previous owner has not put a shim on the front of the trigger housing. Doing so will tighten the housing up but not correct the improper angle.

Wrong Right