I recently purchased and installed an SR9-T "Match Barrel" from RCM on my target rifle nicknamed the GHG1 (ground hog gun 1). RCM's spiel on the site touts the Schneider P5 rifling, SR9 length and profile and a "Match Nato Chamber". To be honest, I completely missed the word "NATO" between "match" and "chamber" not knowing that it was going to be a bad mistake.
I took the rifle to the range and couldn't get anything I had with me (various factory ammo and my target reloads) to shoot better than 3.5"~4" at 100 yards. In comparison the bulllpup was shooting the same group sizes with my reloads using a 4X scope.
By definition a "Match Chamber" calls for a minimum spec. neck diameter and short freebore to ensure that the bullet touches the lands of the rifling. Typical .308 "Match" chambers have a freebore of .04"~.05" for a 168gr SMK, arguably the most popular bullet for 30 caliber target shooting in the USA.
I needed to measure the chamber to get to the bottom of the problem and made a longer copy of a Hornaday style OAL gauge so it would reach through the back of the receiver.
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The point of the gauge is to determine the seating depth of the bullet to get the length needed for it to touch the lands of the rifling. Each brand of bullet will require a different seating depth due to the shape of it's ogive. I measured 3 different barrels (3x each) and averaged the measurements for each one using a 168 gr SMK bullet.
First up was an original Santa Barbara produced Cetme barrel with a NATO stamp. I will call it "zero" because it had the shortest freebore depth of the three.
Next was a McGowen barrel I chamber reamed using a Clymer 7.62x51 Nato chamber reamer. The freebore (distance to the lands) was .057" longer than the original barrel.
Last was the SR9 barrel that has a freebore depth .138" longer than the original barrel.
Here's where the problem starts. In the McGowen barrel the SMK bullet is still able to touch the lands and stay in the case mouth securely. In the RCM barrel the bullet is extended so far to touch the rifling that it literally falls out of the case and would be too long to fit in to a magazine.
I traded several emails with Mike Szabo last night, someone said he was the owner of RCM, I don't know. He claims the chambers of the SR9 and PSG1 barrels were purposely cut with extra long chambers and has coined the term "Match NATO Chamber" to cover himself. He has repeatedly said it was the buyers responsibility to work up an accurate load and suggested I start with Berger VLD bullets because they are better suited for jumping long freebores. He was completely aware of the extra long freebore distance.
It boggles my mind to think that anyone would purposely cut the worst chamber possible into one of the best match grade barrels available. In his last communication he said:
So buyer beware, the SR9 and PSG1 barrels will only shoot acceptably accurate with a special load you'll need to develop because of excessive freebore causing bullet jump to the lands. I have spent hours on the net trying to find any reason that someone would want bullet jump in a match barrel and came up dry.Load development is detrimental to achieve accuracy. Especially on a semi automatic. My reamers are designed and manufactured by highly qualified and skilled cutter grinders. Having a zero free bore doesn't make it a match chamber. Just the opposite. I'm convinced your knowledge in reamers is limited as with your ability to develop a load for your new build. You brought to my attention that I need to state that these barrels will shoot any military surplus but to achieve maximum results in accuracy load development may be needed. Thank you for bringing that to my attention.
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