- First time with two barrel bands
- Second time with two barrel bands
- Third time with two barrel bands
First time with two barrel bands
Okay, so I couldn’t give up on tuning, and had to take things a step further. Over in Part II of Bedding the rifle I told about how I replaced the factory barrel band with a ‘tunable’ barrel band, and the good results I got. Well, after that, I got to scratching my head, which can be a dangerous thing.
One thing that really bothered me is how I got smaller groups with a tighter barrel band, and also got a point of impact close to an inch lower at the same time. This was not because I was torquing the snot out of the barrel band, because I wasn’t. There was only one very obvious conclusion: the factory barrel is really flexible.
With a tight takedown screw, and a tight barrel band, I was bending the barrel downward, with a hump between the two. With a bit of imagination, it wasn’t hard to see firing a round maybe punching the barrel straighter for a millisecond, and then going back to ‘the hump’. If this was going on, it would be creating something like vibration, or maybe more like flexing.
So, I thought: what would happen if I added another tunable barrel band, between the one in the front, and the takedown screw? Pull the whole barrel straight down, instead of pulling a curve into it?
What I did was measure the half-way point between the front barrel band and the takedown screw, and put the second tunable band there. To do that I got another stainless steel U-bolt, one size larger than the one in the front. With a round file, I cut a relief on each side of the stock, maybe 1/8″ deep, for the ‘legs’ of the U-bolt, and cut a flat spot on the bottom of the stock for the strap to rest on.
Here are the group results, as usual, at 30 yards with open sights:
A. Everything ‘merely assembled’ – takedown ‘feels flush’, front band and middle band both 1/4 turn on each nut past ‘merely together’: 0.945″
B. Same as A, but front band another 1/4 turn tighter on both nuts: 0.66″
C. Same as B, but middle band but another 1/4 turn tighter on both nuts: 0.55″
D. Same as C, but takedown screw fully tight: 1.322″ (Wow.)
One other thing: the point of impact returned to the center of the target.
So, the best setup is everything ‘merely assembled’, plus 1/2 turn on each of the four barrel band nuts. What this says to me is, it’s important to pull down evenly on the barrel, with even pressure, when attaching it to the stock — and float the receiver, not the barrel. And please bear in mind: this is with the barrel bedded in RTV. With different bedding, or none at all, I wouldn’t even try to guess what the results would be.
Here’s a pic of what the rifle looks like now, which isn’t all that bad, I think:
Second time with two barrel bands
After the first time out with two barrel bands (above), there was still reason to do some head-scratching. Mainly, what if the rifle needed only one barrel band, but in the middle?
So, here are the results from the latest round of shooting. Again, open sights, 30 yards, Remington 36-grain brass plated hollow points, groups of five.
1. Same as ‘C’ above, under ‘First time out’, just to warm up/benchmark: 0.76″
2. Same as ‘C’ above, but with front barrel band removed: 0.8925″
3. No barrel band at all, takedown screw extra tight: 1.305″
4. Takedown screw removed, middle barrel band 1 1/2 turn on each screw past ‘merely assembled’ – .93″
5. Same as in 4, but front band back on and 1/2 turn on each screw past ‘merely assembled’: 0.942″
6. Same as in 4, but front band now 3/4 turn on each screw past ‘merely assembled’: 0.58″
7. Same as in 6, but subsonic ammunition: 0.88″
8. Same as in 6, but middle band now 2 turns past ‘merely assembled’: 1.235″
(By the way, I just put a little article in Miscellanea about how I measure groups.)
When I look at this, I see more support for the notion that you should bed the barrel, float the receiver, and put pretty decent torque on both barrel bands.
The difference between 6 and 7 are interesting. Over in ‘Bedding the rifle’, I got a substantial improvement in a nasty set of groups, simply by switching to subsonic ammo. This time around, switching from standard ammo (in 6) to subsonic (in 7) made things worse.
What this says to me is that ‘finding ammo the rifle likes’ has a real basis in fact. What this also means is that it’s possible, with two tunable barrel bands, to tune the barrel to fit the ammunition.
But, what should I make of the results in 8? What I’m thinking is that with the extra torque on the middle barrel band, it’s pressing the receiver down against the pillar gasket, which has the effect of bedding the receiver all over again — even though the takedown screw is gone for everything from 4-8.
So, the next test will be to try 6 and 8 again, but with the takedown screw and pillar gasket both removed. I’ll do that test another day. What that might indicate is that when bedding the rifle, temporarily use a spacer in place of the pillar gasket, such as an O-ring perhaps, and when the bedding is complete, throw it away.
Third time with two barrel bands
Okay, here are the results with both barrel bands down tight, no takedown screw, and the pillar gasket removed: 0.64″ and 0.70″. I did another group with subsonic, and got 0.61″. The conclusion I’m drawing: bed the barrel, torque both barrel bands, float the receiver.
With all this work behind me, I’m taking these results as a benchmark for how the other three Rugers shoot. These other Rugers are:
- my wife’s (which I’ll call the ‘Red Ruger‘), with the JPRE-2 muzzle brake, .854 Lyman globe front sight with Lee Shaver crosshair/aperture reticle, and Williams receiver-mounted notched leaf sight
- spare Ruger #1 (which I’ll call the ‘Green Ruger‘), with GRG muzzle brake, .584 Lyman globe front sight with Lyman small blade reticle, and Millet/Desert Eagle rear sight
- spare Ruger #2 (which I’ll call the ‘Brown Ruger‘), which will get a scope.