Grendel Bolt not accepting Cam Pin

[Fillar]

Grendel Bolt1.jpgGrendel Bolt2.jpgGrendel Bolt3.jpg

[dukeboy_318]

Do you know the manufacturer by chance?

As for having it machined, a good machine shop could probably do it for you.

[Fillar]

The seller said he bought it from Satern.

[bwaites]

The seller said he bought it from Satern.

People on the board reported that Satern had a bad batch of bolts sometime last year or maybe in 2011, if I recall correctly.

The problem is that I don't remember Satern selling any hard chromed bolts.

[Fillar]

Anyone know a good machine shop that I can send this off to? It's a spare, so I'm fine with waiting a month-plus.

[smoke13]

I bought a chrome bolt from satern as a replacement to the one that came with the barrel in 2011. It was a 7.62x39 bolt and the extractor was one of the modified .223 extractors to fit the .30 cal diameter but it had sharp edges that had to be deburred. I was not too overly impressed with it, but it functions.

I recommend you polish the diameter down on the cam pin until you have a nice fit on the bolt with a dremmel. I wouldn't risk messing up the bolt. You can replace the cam pin. To modify the hole on the bolt it would need to be reamed by a good machinist on an end mill, and it might require a special reamer diameter. Probably not a feasible option.

[dukeboy_318]

if you decide not to mess with it, I'll buy it from you. I'll even pay what you paid.

[Longshot_34]

+1 for altering the can pin. Always alter the cheaper of the two parts.

[LRRPF52]

Sounds like it was chromed as an after-thought. Can you please measure the bolt face depth and report that to us. You can use your calipers as a seating depth tool with the end that slides out of the scale body. Your dail will work just the same.

[Fillar]

Dukeboy just bought it. I guess I'll put myself on the long waiting list for a spare AA bolt. Thanks guys for the ideas and help.

[dukeboy_318]

Just thought I would update.

I purchased the bolt from Fillar at the cost he paid. I received the bolt from UPS yesterday. Being a former fabricator, I'm used to making objects fit where most cant. Anyway, I went to my shop this morning.

Within about 30 seconds, I saw 2 problems with this bolt. First, just slightly down inside the bore for the cam pin, there was a burr sticking out just slightly. The 2nd thing I noticed was the slight, very slight egg shape of the bore.. I then took measurements of the several cam pins I have in other rifles, they all measured .3100 inches on a certified to the .0001, recently calibrated digital micrometer.

***Now for the disclaimer. If you have little to no mechanical or fabrication experience, I do not recommend you try this on your own should you run into a similar situation. I am not responsible for any ideas this may give you.***


Once I got those measurements, I then took a grease pencil and a straight edge and marked 6 places around the bore. I then took measurements from those 6 places, 4 of the 6 measured .3105, the other two measured .3090 and .3085. I then took a spare cam pin, decided to try making it fit those measurements. I discovered that while I could make the cam pin fit in the bore, it would not rotate and it would get hung up, presumablly on the burr inside the bore.

At this point, I decided the best option would be to round out the two areas that were smaller and remove the burr. I took a Dremel and a 4200 grit sanding stone bit and smoothed out the bore and removed the burr.

I then took measurements of all the same spots. I managed to get it almost perfect, can't even tell without a magnifying glass that anything was messed with. Now a standard, unmodified cam pin fits in and rotates as it should.

New measurements show that I made the bored round out to .3107. I'm sure .0002 of inch will not weak the bolt and so far it manually cycles fine in my grendel. I have not fired it due to the weather, but hopefully this weekend, I can try it out. I am confident in my work, I measured my other AR bolts, the bores for the cam pins on the other 2 are .3104 and .3109 so I'm not worried at all with it. This whole process took longer to tell than it did to make it work. Within 15 minutes, I now have a working bolt.

I do have pictures to post once my wife gets home and I can get the camera cord out of the car.