260 yards, 14 power
This is another NOE 81.5 group. And it was fired at 14 power from 260 yards like the title says.
It was the third group of the day. I had just lowered the air pressure from 3700 PSI to 3500 PSI I had latteral stringing from the valve not opening consistanly at 3700.
The first three shots were just to the left of the 8 inch gong, in 3/4 inch, so I corrected for a light left to right wind and fired these 5 shots.
And Synopsys, I did not shoot off my Ford Explorer hood, for two reasons, one my daughter has the Explorer due to her snow in the mountains where she lives, and I was shooting from my deck and if I had the Explorer, I am not sure the deck would hold it up. 😛
So I use a Caldwell Stable table these days, Harris bipod in front and a caldwell range bag in back.
.90 moa.
Regards,
Roachcreek
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I think the whole bipod vs. rest controversy will never end. I say that because I have a gun that will shoot ever so tiny groups off the bipod when set to low power but needs to be rested to get the best results when set to high power.
I surmise that the cause is due to harmonics. If nothing else, the high and low power vibration levels differ in magnitude. I expect that the longer hammer stroke and changed valve bounce characteristics might have and impact on magnitude and maybe frequency as well.
RC and Ced have both installed barrel dampers and have been pleased with the results. Those dampers are generally advertised as reducing barrel harmonics but, because they have mass and can be located at different positions, they can also affect the null points of vibration waves by changing the characteristics of the barrel being vibrated. Ideally, the muzzle becomes a null point and does not move even if the barrel whips like a rope.
If you have a bipod mounted at a null point, no vibration gets transmitted to the bench and no feedback or bounce gets returned. If your bipod is mounted at a peak point and the legs are on a hard surface, it’s possible that vibration can feedback before the bullet leaves the muzzle. Of course, if the vibration is very low or you are exceptionally consistent, you may not notice or compensate.
If you wonder how the vibration could feedback in time to affect your shot, consider that the speed of sound in steel is about 20,000 fps and a little faster in aluminum (over 21,000 fps). The vibrations from hammer strike and the rapid expansion of the air behind the bullet can make it down the barrel and air tube and back far faster than your 1000 fps bullet can accelerate down the barrel. But bipods have rubber feet and the speed of sound in rubber is slow! Yes, but if you only travel a 1/10 of an inch…
For the bench bag. the speed of sound for the fill material might still be very high or might be very low. It doesn’t matter so much though because the very nature of little bits of stuff in the bag means that you will go from efficient linear propagation to spherical propagation and most vibration will die out before it ever gets to the bench much less feeds back.
BUT! The bench bag will generally change shape a little bit from shot to shot due to settling and if you place it at a peak point, you can get feedback just from the mass of material trying to respond (move) from the gun vibration.
Good thing about the bag rest is that you can move it fore and aft like you would a barrel damper. The bad thing is that every shot is from a different position…
It’s got to be a pure comfort thing. I like the bipod because it is simple and works in the field, a rest is a pita if you don’t have a bench.
The best thing I have used yet is a field target bum bag filled with plastic stuffed animal filler (the bum bag weighs nearly 20lbs) but it is moldable so it conforms to everything it sits on and provides a plenty stable platform.
I use it under my USFT for VAR shilouettes, no rear rest besides my hand under the butt on the table to adjust elevation (plus VAR rules don’t allow a rear rest).
On my PB I do the best with sliders on a front rest and a slider in a rear bag.
IMHO the lower the rifle is to the table the better the groups (granted your seat position allows for a non contorted and relaxed sight picture).
Ah that northwest weather, Portland drove me nuts when I was remodeling a house. The second i’d pull the tarp off the roof it would RAIN then stop when I got the tarp back up. 👿
1000 psi for 33 shots at that power is impressive. Looks like you are having fun up there too. 😉
Syn,
I researched a bit on bench rests bags. I heard pro and con from some really good benchrest shooters on the benchrest forum about bipods. No one seems middle of the ground on them, they love them or they hate them.
And correct me if I am wrong, but I think that the winner this year at AOA’ Benchrest competetion, Fredrick of FX Airguns, used a bipod on his Boss.
I do notice some shots that string low, and I have wondered if that is the hammer slam manifesting itself thru the bipod, but it could be a lot of other things when you shooting cast bullets. Or enviromental things like a swirling gust of wind like I have here on the vineyard on most days as the storms pass over.
Yes I shoot regulated from a 44 cf bottle, I have a Pygmy bottle, but it would last as long as that fart in a windstorm I refer to now and then.
Today I went from 4600 PSI to 3600 PSI in 33 shots, so you can see the little Pygmy bottle, while fine for the Royale or the Rapid just does not cut it for a big bore of any kind.
I am really liking this NOE mold, so much I ordered a 100 grain version of it today. That 4 cavity puts out lot of accurate bullets and fast.
Some more groups just fired. Same POA as before, just the wind switched from left to right to coming from behind and to the left.
RC
What happened to the Benz?
Wouldn’t fit out the door to the back porch? 😆
How do you like shooting off a bipod? I found it caused some inaccuracy for me. Went to a front rest and things got a bit better. Harris makes a beautiful bipod, bought a couple non-Harris ones prior to getting the real deal. They are all gone yet the harris remains!
You shoot of a regged buddy bottle? 😯 Putting that new SB to work I see! 😉
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The bag and rifle I shoot off the bench are not like anything out there. I run a height adjustable plate under the action (air tube and barrel are cantilevered and do not touch), so the 4″ wide by 10″ long 5/8″ thick plastic plate sits on the bag under the “receiver/barrel block”.
The bag is a field target bumbag, 6″ tall, 12″ wide and 18″ long. To fill it tight would require 10, 2lb bags of the poly pellets (each pellet is a blob kind of thing just over 1/8″ around and not a sphere) I put in 18lbs and this thing is heavier than sand or crushed walnut shells by a long shot. The pellets are like hard hot glue gun plastic and have some friction between them because of the type of plastic.
My plastic rest sits down a little in the pellets but doesn’t continue to settle after it is placed and my USFT it HEAVY. There is some sand that when you push one side it pushes up in another because all the pieces are the same shape (non-compactable) because of the bead shape it will compact instead of shifting around.
Only downside is it is HEAVY to carry for field target competitions. Other than that I have yet to find a better fill material for a bum bag or bench rest bag.
http://www.fairfieldworld.com/product/32-poly-pellets-weighted-stuffing-beads