Gunsmithing Problem with FN SPR chamber???

[Boondocker308]

After purchasing a FN SPR action off of gunbroker a while back, I tracked down a smith on the Hide to true the action, and chamber and install a barrel. After a mishap with weak packaging and rough UPS handling I got my barreled action. Got to looking more closely at the setup last night and I noticed that the barrel/chamber did NOT have a cut in it for the M70 extractor. This made me compare it to my Winchester M70 hunting rifle and my fathers (both controlled round feed) and I noticed a few differences. There's no extractor cut, the barrel all around the chamber is cut at 90 degrees, and there's several threads showing from the action. Some searching around the Hide makes me think that the geometry is not correct as it appears the proper cone hasn't been cut into the chamber entry way (not proper terminology I'm sure). The coating is gone from the very front of the extractor and there's some marks on the barrel next to the chamber which suggests the extractor is hitting the barrel. Also noticed that when a round is chambered the last inch of travel from the bolt gets noticibly more difficult. After ejecting the round there's shiny smudge marks in the brass. If I drop a round into the chamber (no bolt) it drops in smoothly but seems to stick up from the aft face of the barrel by 3/16" of an inch. I plan on contacting the smith tomorrow but I just want to confirm with the Hide guys that this is not correct smith work for a M70 type chamber. Thanks for any help. Pics added.

 

[treebasher]

Re: Problem with FN SPR chamber???

This is what the breech looks like for a FN SPR / Win. Mod. 70 with a "claw" extractor:

 

[turbo54]

Re: Problem with FN SPR chamber???

If it doesn't have the coned breech, and lacks the extractor cut as pictured above. It's wrong.

Your smith needs to make this right.

A couple nuances regarding the picture posted above:

1. The bottom of the cut pictured was done on an angle, probaby by a keyway type cutter, which is great, but sometimes the bottom of the extractor cut will have a flat bottom, which is ok too. I've seen Winchester barrels (done at the factory) BOTH ways, so I wouldn't say one method is "better" than the other, though I think the most "traditional" way is with a keyway cutter, with the angle.

2. The picture indicates too little bolt-nose clearance, as evidenced by the rub marks on the coned breech, starting just beneath the extractor cut and continuing around (clockwise) to the 6 o'clock position. That is from the boltnose rubbing on the breechface. Surely the boltnose has some rubmarks on it also.

Lastly, the shiny rub marks on your brass and extra resistance putting the cartridge fully into battery is most likely a brass-size issue, and not a chamber issue. Is the brass brand new? What cartridge? What were the reamer specs the chamber was cut with?

 

[Boondocker308]

Re: Problem with FN SPR chamber???

Thanks for the help guys. I still plan on posting pics tonight and contacting the smith tomorrow. In response to the brass, the latest I tried was a factory FGMM.

 

[Boondocker308]

Re: Problem with FN SPR chamber???

Added pics

 

[treebasher]

Re: Problem with FN SPR chamber???

Yep, you better be having a talk with your gunsmith. I would be worried about that much case hanging out in the breeze, unsupported.

 

[buffybuster]

Re: Problem with FN SPR chamber???

Looks like the smith barreled it essentially like a Mauser M98. DEFINITELY NOT the way it was designed

 

[turbo54]

Re: Problem with FN SPR chamber???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: treebasher</div><div class="ubbcode-body">Yep, you better be having a talk with your gunsmith. I would be worried about that much case hanging out in the breeze, unsupported. </div></div>

That chamber poses no safety issue, assuming headspace is correct.

Actually, that Casehead is very well supported. Remember, the case is solid (save for the flash hole) for about 3/16" forward of the extraction groove.

A case sitting in a [proper] Remington chamber *appears* less supported than that one.

Honestly, there's probably nothing really "wrong" with this guys chamber, other than slightly less reliable feeding and it's not traditional.