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+--- Thread: Grendel Bolt not accepting Cam Pin (/showthread.php?tid=4962)
Grendel Bolt not accepting Cam Pin - Fillar - 02-20-2013
I recently purchase a chrome 6.5 Bolt, at a premium, from a member here. It seems like it is defective. Ive tried multiple Cam Pins, and none will fit. Ive measured the opening, and the cam pin should fit. Its almost like it isnt a perfectly round circumference; similar to attempting to slide the cam pin into the wrong side of the bolt. It's not a lefty, it won't work on either side.
Do you think its an option to take it to a machine shop and have them bore it out? Or am I just out $120? Has anyone run into this? Is this not a Grendel?
The Chrome Bolt is the one I purchased via Pay Pal, the one on the right is my AA Bolt. Youll see in the second image the cam pin slides right into the AA bolt.
[ATTACH=CONFIG]3047[/ATTACH][ATTACH=CONFIG]3048[/ATTACH][ATTACH=CONFIG]3049[/ATTACH]
Grendel Bolt not accepting Cam Pin - dukeboy_318 - 02-20-2013
Do you know the manufacturer by chance?
As for having it machined, a good machine shop could probably do it for you.
Grendel Bolt not accepting Cam Pin - Fillar - 02-20-2013
The seller said he bought it from Satern.
Grendel Bolt not accepting Cam Pin - bwaites - 02-20-2013
Fillar Wrote: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.
Grendel Bolt not accepting Cam Pin - Fillar - 02-21-2013
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.
Grendel Bolt not accepting Cam Pin - smoke13 - 02-21-2013
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.
Grendel Bolt not accepting Cam Pin - dukeboy_318 - 02-21-2013
if you decide not to mess with it, I'll buy it from you. I'll even pay what you paid.
Grendel Bolt not accepting Cam Pin - Longshot_34 - 02-21-2013
+1 for altering the can pin. Always alter the cheaper of the two parts.
Grendel Bolt not accepting Cam Pin - LRRPF52 - 02-21-2013
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.
Grendel Bolt not accepting Cam Pin - Fillar - 02-21-2013
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.
Grendel Bolt not accepting Cam Pin - dukeboy_318 - 02-27-2013
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.