Criterion Barrel Throat |
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britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Online Points: 6539 |
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Armorer, will it shoot sub-MOA for 10 rounds consistently? I can show you lots of tiny three shot clover leaf groups at 100 yards, 1/3 MOA or less, and 5 round groups not much larger. But getting 10 consecutive shots under 1 MOA is tough to do, barrel vibration will inevitably cause a “flier”. In shooting many 10 shot groups off the bench with a scope with match ammo thru a Fulton match prepped rifle has lead me to conclude 1 to 1.5 MOA is more typical for 10 shot groups. And that’s what the Bisley Queens Prize winners have stated in the historical records for the No. 4. (1.5 MOA was considered to be an exceptionally close grouper). When the No. 4 was the rifle used in Service Rifle competition, the target bullseye was 2.5 MOA (200, 300 and 600 yd targets) even then, shooting clean scores was not easy. This was with Mk 7 ammunition produced for the matches.
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britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Online Points: 6539 |
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Since the OP is about throat erosion affecting accuracy, below is an example of the first five shots off the elbows, no support, PH 5c aperture sight. Rifle is A 69L Long Branch No. 4 Mk 1/3, BSA 5 groove barrel with a very loooooong throat. 174 gr SMK seated to 3.05 cartridge overall length, the bullet is about 1/2 inch off the lands, yet the rifle is still accurate for its intended purpose. Of course, accuracy is a relative term.
600 yards, first 5 shots in just over 6 inches (1 MOA). The next 5 opened up the group to 12 inches (2 MOA), some of that was undoubtably me, a few of the last shots dropped just below the edge of the 10 ring. The 10 ring on the US NRA Medium Range target is 12 inches (2 MOA). It’s tough keeping all ten shots in the 10 ring (Score of 100) with an aperture sight, regardless how accurate the rifle is, even for a NRA High Master shooter (average score of 97/100 or higher on the High Power Service Rifle course). |
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The Armourer
Senior Member Joined: June 23 2019 Location: Y Felinhelli Status: Offline Points: 1246 |
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Once out of 'lock-down' I'll try and see what I can do. The rifle can manage much better than I can, so everything needs to come together on the same day. |
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britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Online Points: 6539 |
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I’m in that same boat. Range is closed for at least the next month, possibly longer. On the plus side, I’ve now got some time to tinker with the Velo and re-blue the Long Branch Mk 1/2.
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A square 10
Special Member Donating Member Joined: December 12 2006 Location: MN , USA Status: Offline Points: 14452 |
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dont forget to post the end results , we do want to see that saved rifle when your done , im glad i never touched it so that the right person puts the finish on it
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105GunGrunt
Groupie Joined: February 08 2020 Location: California Status: Offline Points: 26 |
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Here is what is driving my questions about the Criterion barrel, and whether to swap out my current barrel. After I bought my No 4 I completely disassembled it and reassembled it starting on Page 1 of Wadham's book on accurizing the Lee Enfield. I did a light bedding of the front and rear of the receiver and made sure I had a floating barrel with the 4-5# pressure from the forestock. From a bench rest I am lucky to keep 10 rounds in the black (a 13" bullseye) at 200yds. I am comparing this to being able to keep 20 rounds in the 10 ring (7" bullseye) using only a sling in the prone position when firing my M1917 (Pattern 14 in .30-06) or my 1903A3 Springfield. I even manage to keep most shots in the 10 ring with my M1898 Krag at the same distance. The bore of my No 4 looks good and a lead slug revealed the barrel had a lot of life left in it. Are my expectations for this rifle just too high??
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britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Online Points: 6539 |
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No, they are not. In my experience on the firing line of the CMP VMR matches, the No. 4 will do every bit as well as a 1903. You should have no trouble holding the 10 ring on the SR target with a high x count prone in sling. Are you using handloads in the No. 4? I had this problem with a M1 which had a brand new barrel installed by the CMP. Turns out there was no rifling at all in one side of the throat, most likely from a bad finish reamer. The bullet likely corkscrewed down the bore and out the muzzle. A new barrel solved it, one I installed myself. No way to say if the problem with your No. 4 is the barrel, but if you have eliminated everything else, then I would find myself a new barrel (Criterion or if you are lucky, a NOS or excellent condition original barrel). |
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