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Posted: 2/2/2013 2:52:52 PM EDT
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Factory built Cugir PSL with custom work by yours truly. Burned the factory wood and replaced with Rhineland Arms Tiger Maple Kit. Also added a black micarta grip panel to stock. Added a power custom trigger and jetted the gas block . Tapped it 8/32 and installed drilled 8/32 stainless steel set screws. I made three different sizes. .050, .062, and .070. Just installed the .062 and it works great. Rifle doesn't beat it self up. The brass use to go 20-30 paces now aprox 8-10 ft. Then added a custom barrel tensioner that I made with a block for QD front sight.
So many of the PSL rifles only shoot decent with one type of ammo or none at all so I wanted to make this one tuneable. Action was blasted and coated with matte black oven cure Cerokote. The barrel tensioner is torqued in between 35-65 in/lbs to find the sweet spot. Bulgarian 147 light ball came in from 5 inches to less than 2 at 45 in/lbs. Brown Bear steel case 174 Match came in at 60 in/lbs. For the money it seemed hard to beat. Shot 1 /2 inch groups with it. Testing was done today at aprox 32 degrees and about 5-8 mph winds. Had to quit before final testing cause I couldn't get a decent feel for the trigger towards the end. It definately showed enough promise to warrant handloads. Groups were shot back to back. Only cooling time allowed was for me to put up targets. Barrel tensioner long is for this PSL, short is for shortened barrel PSL. 
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When you jet the gas block you use the jets to control how much goes through the system. With the small jet in, the heavies don't batter the trunion near as much as 147 light ball does in a factory gun.
MWG started doing tensioners for a few rifles in the 90's so its not originally my idea. They went out of business. You can buy 10/22 tensioned barrels all over now. Same idea, they are just permanently set for tension at factory. It is a machined tube surrounding the barrel. You have to be able to bump it against something like a gas block or a step machined into barrel. you then torque the flashider or muzzlebreak to 35 in/lbs, shoot a group, and continue. Break torque and retorque to a higher setting and shoot a group. Record your progress. Groups will get smaller than increase in size once you go over the sweet spot. Break the torque, loctite the flashider and torque it to optimal setting. Let the loctite set up and your GTG. If you go to a different weight ammunition, you can find what is best for it. It does not make a great shooting rifle better. It can really make a difference in a marginal shooting gun. Or one with a pencil thin barrel such as a PSL. With the right setting it shoots like a decent rack grade M1A when the PSL is hot. I have done several different guns. Deawoos, AKs. HK91. Made one for a 91 that shot 2 1/2 in groups with Federal 168 match. It came in at 62 in/lbs and shot consistently 1 to 1 1/4 inch groups. Here's another PSL and an AK This Ak shot 8-10 inch 3 shot groups. It was terrible. Made the tensioner out of solid barstock. 42 in/lbs was the sweet spot.got it done to 3-4 inch grouops with wolf and 2 inch with Chinese steel core. 
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Shorty PSL. customized, jetted gas block, folding, collapsible stock, barrel tensioner, power custom trigger, shortened, re-crowned and threaded barrel.
Also DPH ARMS Saiga all aluminum tri-rail modifed to fit PSL and free floated from barrel trunion forward with this piece I made from mild steel 3/4 steel plate. 
Still shot like a PSL before and after barrel shortening. Put on the tensioner and flashider, torque at 50 in/lbs brought groups from 4 inch to 1 1/2. Course I had to look (shoot) through the ranges. 
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Forgot to answer, on the gas port issue. There was a guy on here that did a nice write up about it and posted a picture. The 8-32 tap and set screw is not my idea, someone else's. But it was a damn good one so I used it,
on both my PSL rifles. Not my picture, someone else went through the hassle of drawing this up. But using it helps you get the idea. Set the rifle up in a padded vice and slowly tap the hole in the gas block, use plenty of tapping fluid and remember to break the chips. 
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How many groups, of how many rounds, are you shooting between adjustments when you are trying to find the best torque?
It seems that you would need to shoot a bunch to account for the inconsistency of the system and its ammo. A couple of summers ago I shot a quadruple-shit load of ten round groups at 100 meters over many range days with a PSL and a variety of ammo. I had 10-shot groups that went into anything from 1.5" to 7+". With less consistent ammo (like most x54R) sometimes the variables stack in your favor, and you get a falsely good group (10 shots in 1.5") and sometimes they stack negatively to produce a misleadingly bad group (7+ moa). Seems like you'd want to shoot a lot between adjustments to get a true value. |
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Quoted:
How many groups, of how many rounds, are you shooting between adjustments when you are trying to find the best torque? It seems that you would need to shoot a bunch to account for the inconsistency of the system and its ammo. A couple of summers ago I shot a quadruple-shit load of ten round groups at 100 meters over many range days with a PSL and a variety of ammo. I had 10-shot groups that went into anything from 1.5" to 7+". With less consistent ammo (like most x54R) sometimes the variables stack in your favor, and you get a falsely good group (10 shots in 1.5") and sometimes they stack negatively to produce a misleadingly bad group (7+ moa). Seems like you'd want to shoot a lot between adjustments to get a true value. And then change the torque to confirm its the tensioner that's giving the groups and not some other variable. Its called scientific method. |
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Shot 4 types of ammo, 3 rd groups each at every 5 inch lbs from 40 to 65. No time in between
except to tape up new targets. Rifle was hot. You could see the groups close then open back up for each type of ammo. Been doing the tensioners long enough to know what works and what doesn't. Shooting groups and letting the rifle cool shows nothing. This amount of pics don't come close to what I fired. I shot for 4 hrs. Had a premium match grade barrel custom chambered on a bluprinted bolt action give terrible groups. That barrel just had stress in it. Kept cutting 3/4 to one inch off and recrowing and even that one hit a sweet spot. More than one way to change harmonics. Lot of guys have chopped their barrels on PSL and they shot a lot better. Except for the velocity there's not a lot of difference in results. Both change harmonics. One is tuneable, the other is not. Take the front sight off one of your threaded AKs. Get a piece of seemless tubing that is big enough to fit and install it behind a flash hider. Get a few types of ammo and go to the range. It is going to take hours and a lot of shooting. You will see a difference. The better (consistent) ammo you use, the more refined your results will be. Hell a couple boxes of that Hornady Zombie ammo with the 123 will give better results than 90 percent of what else is out there. I've still got some Chinese steel core that amazes me with the accuracy out of a NHM-91 heavy barrel. When I get some time, I'll probably be doing this again with a reload of Sierra 150 .311 SP over a load of 4064 or H4895. But those tests will be done with the shorty, as I am only keeping one. |
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I think that the work that you did on the rifle looks excellent.
However, where i disagree with you is on your testing methodology. I don't believe that a three round group produces enough useful data to make a change. Three round groups will expand and shrink between groups based on any number of variables, and with a PSL and x54r ammo, those variables are significant. |
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If you're using your torque wrench with a crow's foot, you aren't getting accurate torque readings.
You need to use the formula here, http://www.engineersedge.com/manufacturing_spec/torque_wrench_1.htm, to calculate the actual torque value. |
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Quoted:
If you're using your torque wrench with a crow's foot, you aren't getting accurate torque readings. You need to use the formula here, http://www.engineersedge.com/manufacturing_spec/torque_wrench_1.htm, to calculate the actual torque value. That is correct in absolutes ... but all that matters in this case is relative. We don't need to know the exactness of any setting, only how to return to it with the same tool. |
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Quoted:
If the crows foot is at a 90 degree angle to the center line of the torque wrench, it does not increase the length. So it should not increase the torque. At least that's what they taught us (or what I remember) in aviation repair school. You are correct, having the crows foot at 90 degrees does not increase the torque. |
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