8mm RM/200SMK COAL questioned

[hypertex]

I just got one of those nifty Stony Point gauges and was finally going to nail down the bullet jump, etc. OK, Sierra 200 SMK's with a book COAL of 3.600 inches. Upon measuring with the gauge, I find that the lands start when the COAL is 3.75
WTF? That's a pretty huge jump, isn't it? I only have about 1000 rounds down the tube and she's really shooting sweet right now. I'm mean incredible like ~1/4 MOA @ 1000 yds.

Should I be concerned? Or should I just throw the gauge away and keep doing what I'm doing?

Remington 700 blueprinted
Original sporter barrel
McMillan A5 stock-bedded
FTE brake
Timney BR trigger

 

[our gang]

Re: 8mm RM/200SMK COAL questioned

There is a trick with stoney point gauges. insert the cartridge and bullet into the chamber. then take a dowel and a hammer and rap the case head in until the cartridge is full seated. then screw in the measuring tube and do your measuring. just pushing it in frequenlys will give false readins

BYW excellent article on 8mm remmag by Boddington in new Gun & Ammo. Fine cartrige that was damnned by it's name and dofus gun writers. Should have called it the 325 Remmag. A bud has a 700 Classic that has killed 10+ Elk using Barnes X and now TSX. Any angle, any ethical range.... BOOM, Dead Elk, one shot never a recovered bullet or any trailing required.

 

[hypertex]

Re: 8mm RM/200SMK COAL questioned

Thanks Mr.H, that's a good idea. I'm not giving up, but I may have been given a false reading as you suggest. The "through the port" angled gauge is likely the culprit here. Since I'm dealing with a belted magnum, I thought I was safe. Will advise upon obtaining the straight model.

Will check out the article. Thanks

 

[hypertex]

Re: 8mm RM/200SMK COAL questioned

Well, finally got around to measuring using the new in line gauge. I removed the pushrod, removed the bolt, inserted the gauge through the rear, tapped on the guage until it felt seated and the pushed the bullet in. The lands still seem to start at 3.75 COAL not 3.600 as the manuals say.
At the last 1000yd shoot, I had one 4 shot group that measured 2 3/4 inches. Needless to say, I'm not going to change a thing -yet.

Has anyone experienced anything like this? - a .15" jump?

 

[FNuser]

Re: 8mm RM/200SMK COAL questioned

I've had more than one caliber shoot Sierras w as much as .2" jump that however is the only brand I've observed that way Bergers usually require a Jam fit and noslers Balistic tip the expected .01" jump.

 

[hypertex]

Re: 8mm RM/200SMK COAL questioned

Thanks Greengo, looks like there's nothing wrong using the SMKs