Author Topic: Bloop Tubes - Effect of weight placement on accuracy (Read 1950 times)

Arizona Jake · « **on:** November 10, 2003, 03:15:33 PM »

OK, Here's a good question for those who have been messing around with this longer than I have:

I purchased a used Anschutz 1808 EDS silhouette rifle that comes with two bloop tubes and a set of detachable weight rings that can slide along the bloop tube.

I know placing weights at different points in the barrel will affect the precision, as vibration is dampened or harmonics are stabilized. What I do not know, is if placing the weight at different locations in the 12" bloop tube creates the same effect. I know the vibration harmonics will be affected, but since the weights are not in contact with the rifle's barrel, I also know vibration will not be dampened.

Has anyone out there investigated this? I would not mind finding out for myself, but hate to spend time and ammo on wild goose chases.

Any and all information is appreciated. Thanks in advance, :?

dave imas · « **Reply #1 on:** November 10, 2003, 07:34:31 PM »

according to Bob, my next door neighbor, benchrest shooter, general tinkerer, and mechanical engineer... moving the weight up and down on the bloop tube acts as if a barrel tuner. if you rifle is shooting well and you move your weight, you could possibly screw up your accuracy. or visa versa. something to play with anyway.
dave

nomad · « **Reply #2 on:** November 11, 2003, 08:58:45 AM »

Jake
After I determine the weight position for a specific ammo, I record the displacement from the muzzle end of the tube with a caliper. Easy to return to that 'setting' whenever changing ammo...
(Works -- within lot variations.)
Could you elaborate on why you feel that weights on the tube don't damp vibration? I've always figured that the weights are still damping the bbl, it's just sort of a 'third party' contact through the tube/bbl connection.

lucho · « **Reply #3 on:** November 11, 2003, 11:33:07 AM »

I put a wieght at the end of my Ans. 54.18. I tried moving the weight around to improve accuracy. I to used calipers and moved the weight a couple of thoousands at a time. I found that moving the weight changed the zero of the ammo, but never improved or degraded the accuracy. I expect a weight on the bloop tube would have the same effect.

My thought is that on this rifle the barrel is so thick and the .22 round so small that the weight doesn't effect the vibrations very much. Please all you benchrest shooter don't get mad at me.

I expect that tuners may work better on thiner taperd high power rifles.

yankee · « **Reply #4 on:** November 11, 2003, 01:14:23 PM »

Good evening. I believe the weights were designed to change the balance of the rifle. The movement may also change accuracy.

nomad · « **Reply #5 on:** November 11, 2003, 01:32:31 PM »

IMO if you're shooting good ammo that your bbl likes -- or that likes your bbl -- you'll see very little change with tuners/moveable weights. (Enough that the stool shooters believe it matters but not something that we need fret over.)
If, however, you're shooting marginal ammo or ammo that's not really compatable with your rifle, you may see significant behavioural differences.
I have a KKMS with a blooper that will show dramatic ups and downs with weight shifting. A 54.18 with bloop tube that used to live in the safe was similar but not as radical. (And I found that it liked Lapua early on, so I never really needed to experiment with it to the extent that I have with the Walther.)

Arizona Jake · « **Reply #6 on:** November 11, 2003, 05:38:57 PM »

Thank you all for the info. I will experiment shifting the weight of the weights in 1/2 inch increments to see what happens with the crappy Fededral 711B ammo I purchased last summer.

By the way, this rifle likes CCI Standard and Green Tag. Over the years, I have owned an Anschuts 64, a Walther UIT, a Sako 78, a Reminton 40X and a Sako FinnFire, and this ammo has always performed well. No difference in performance from lot to lot. I might end up using this stuff for informal matches and the 711B stuff for 50 foot indoo practice.

The rifle also likes Federal 900 and 900B.

Regards,

bob259 · « **Reply #7 on:** November 23, 2003, 05:11:29 AM »

We've been playing with a bloop tube and from what I've observed at 100M I got better groups with the tube vs without it. Same ammo lot and rifle so nothing changed, only the tube. The groups were about a Min different from with out the tube, but the groups were tighter. Nothing scientic in our casual testing.

We did notice at the Nationals that the top shooter (A.Schanez.) was using a Anschutz with an approx. 18" tube, similiar to a runing bore barrel and a lot of other top shooters were using shorter barrels with longer tubes custom made on them. I'd like to try one with a shorter barrel to help with the balance on my 1808.

nomad · « **Reply #8 on:** November 23, 2003, 07:02:50 AM »

Neal Stepp at ISS in Ft Worth, TX usually carries some of the longer Anschutz tubes, including the long, running target variants. 817-595-2090.
Keep in mind that the 30" overall maximum bbl length on std rifles would preclude the use of any tube longer than 14"... (IIRC the 54.18 that I used to have, created from a running target bbld action, had a 19.5" bbl.)