Gunsmithing Chambering problem with the 224 95gn SMK

[diamond]

I'm working up a 22 Dasher with the PT&G print for the Norma 1.600 brass (6 Dasher necked down). Also picked up a throater as I intended to set the freebore for the 224 95gn SMK.

Problem I ran into: The reamer print says the throat is .2243. The Sierra 95s are measuring out at .2244 to .2245. The bullets are hanging up on the lead! I've never run into a bullet that is that much over, most are slightly less. Even with a SAAMI throat reamer at .2245 it's not enough clearance. Talking to Dave Kiff at PT&G he says he goes for .0002 on either side of the bullet. I'd have to throat this at .2249 to get that.

Anyone out there run into this? I've got a call into Sierra to find out if that's actually expected or if I got a bad couple boxes of pills. If this was normal I'd expect to find some discussion but searching hasn't turned anything up.

 

[diamond]

FWIW Sierra got back to me today and said the tolerance spec on the 95g SMKs is .2242-.2244. So I could be off a tenth in my mic but in any case they require a throat/lead that is larger than my reamer print to have proper clearance. I will have to order a larger diameter throat reamer. Kinda locks me in to these bullets but that's what I'm intending to chamber it for so not a big deal. Still kind of surprised I didn't find any discussion online about it.

 

[Rocketvapor]

I'll follow this to see what you come up with as a fix.
Some day I might do my own chamber reaming.
To allow 0.0002" on EITHER SIDE (?) of 0.2243" that would mean a bullet nominal of 0.2239"

I've got 80 and 88 ELD that mic 0.2239" to 0.2241" and Seirra 90's that mic 0.2241" to 0.2242"
(only checked a few)

 

[diamond]

Thanks for checking yours. The 80/88's would probably shoot fine in this chamber. The 90's would be tight but probably still shoot.

Yeah .0002 on either side, or total of .0004 over bullet diameter is what Dave at PT&G recommends minimum for a throat. Maybe could go tighter on a bench rest gun but for a tactical comp rifle that will go 300 rounds or more before cleaning I agree with his thinking. I sent him a couple of the bullets and going to have him cut me a new throat reamer for them after he checks them on his optical comp. Will post updates on how this turns out.

 

[diamond]

Just to follow up. Since Sierra says these bullets are to spec I ended up working with Dave Kiff to get a .2247 throat reamer to give me .0002" on each side of the free bore accounting for his tolerance on the reamer. Set it back and cut a new chamber and this reamer works perfect. So now I'm on to working up some loads. Hopefully this was all worth it and the 95s will end up shooting as well as I think they will. I've only gone out to do some initial break in. It was drilling bug holes but the velocity was pretty far below what I'd expected. Got several other powders to work up tho and the barrel will likely speed up.

 

[Mordamer]

I had a .2245" PT&G throating reamer that was way under spec and caused me to have this problem. My bullets measured .2240 and my reamer actual measurement was .2238. I sent it back and they replaced it in about 3 weeks. I feel lucky, because I have heard nothing but bad reports about their customer service. My experience with this problem and their customer service was actually pretty good, although it would have saved a huge headache if the reamer was right to start with.

 

[Robert Gradous]

I'm working up a 22 Dasher with the PT&G print for the Norma 1.600 brass (6 Dasher necked down). Also picked up a throater as I intended to set the freebore for the 224 95gn SMK.

Problem I ran into: The reamer print says the throat is .2243. The Sierra 95s are measuring out at .2244 to .2245. The bullets are hanging up on the lead! I've never run into a bullet that is that much over, most are slightly less. Even with a SAAMI throat reamer at .2245 it's not enough clearance. Talking to Dave Kiff at PT&G he says he goes for .0002 on either side of the bullet. I'd have to throat this at .2249 to get that.

Anyone out there run into this? I've got a call into Sierra to find out if that's actually expected or if I got a bad couple boxes of pills. If this was normal I'd expect to find some discussion but searching hasn't turned anything up.