Cross Sticks

[Circuit Rider]

Have read about finding the sweet spot on the barrel, and as I have not shot in any matches was wanting to know if my cross sticks are required to be under the barrel or can it be under the forearm? Whether I ever get to shoot in a match,I'd still like to be doing it correctly. Thanks, Circuit Rider:lovebooli

[cajun shooter]

This is one of those things that will take you a while to work on. By that I mean if it indeed works or not. You have followers on both sides. I'm in the wait and see group. While going through some FBI training for long range rifle we were told to never put the barrel itself on any support. The reason is that you mess up the harmonics of the bbl. I see shooters put bbls on the sticks all the time. The question is did it change the shot. That will take some range time to prove or make it a falsehood. Maybe some of our LR shooters will chime in as to what they do. Later David

[August]

Can be where ever you want it. Most of the big boys have the barrel supported at the point of primary harmonic to damp it out. When you go to a match, you see wear on the barrels of competitors guns at that support point. Find someone with a rifle like yours and copy them.

[montana_charlie]

Have read about finding the sweet spot on the barrel, and as I have not shot in any matches was wanting to know if my cross sticks are required to be under the barrel or can it be under the forearm?
You can rest the rifle on any point you wish. Many choose the forearm. If you have a two-piece stock with a separate forearm that is attatched directly to the barrel, be certain the rear of the forearm does not (quite) touch the metal of the receiver.
Otherwise, your barrel harmonics will change with every variation in humidity or barrel temperature.
This holds true even if you don't rest on the forearm.

Some choose the forearm rest point because of experience with modern rifles. They (typically) have the action and barrel bedded to the stock in a manner that insulates barrel whip from being allowed to cause 'bounce' (free floated)...or they create a situation where the amount of whip is dampened by intentional contact with a part of the forearm (pillar bedded) and the effects of harmonic-related barrel bounce are minimized.

The 'sweet spot' on a BPCR gun is that point on the barrel where harmonics are nullified by the physical properties of the barrel, itself.
It's also called the 'null' point, and even guitar strings have them.
There are a number of methods for finding the null on a given barrel, but this is the easiest.

Secure (or remove) anything that rattles. If the rifle has a double set trigger, set the rear trigger so it can't vibrate.

Hold the rifle by the receiver, hanging muzzle down.
With your other hand, strike the barrel lightly with a mallet (plastic, nylon, rawhide...brass only if nothing else is available).
The barrel will probably 'ring' for a second or two. If it doesn't, you may have hit the null on the first strike.

This doesn't need a hard hit. When I want to re-locate the null on my Sharps, I use my knuckle instead of a mallet.

Tap up and down the barrel's length, between the forearm and a point near the front sight.
Tap and listen, tap and listen, tap and listen.

At some point along the barrel you will be getting 'thung', 'thung', 'thung' as you move along...and then you will get 'thup'.
Tap the 'thup' point a time or two to find exactly where it is, then try above and below it to make certain.

The 'thup' point is the sweet spot where you rest the barrel on anything solid...such as cross stix.
It's also a good choice when resting on sandbags, or anything else.

To be fair, I should say that some very good shooters ignore the sweet spot.
They pick a spot out near the muzzle and rest the barrel there. By always using the same spot, the 'bounce' is (should be) always the same...for that load, on that day.
When it changes, a sight adjustment corrects for the difference.

By resting as far as possible away from the shooter's shoulder, any movement by the shooter is less of a factor in a steady hold.
They feel that advantage outweighs the value of using the sweet spot.

The point for the 'muzzle rest' is just far enough back so the barrel doesn't slip off of the cross stix under recoil.

CM

[Circuit Rider]

Montana Charlie, The many posts I've read of yours assures me, you know of which you speak. I will try that method and report back. I understand about some shooters ignoring the sweet spot and using the same location on the barrel each time. As an aside, I entered Alberta at Sweet grass Nov. 5th '08, delivering boats to Whitehorse in the Yukon. Had only been thru Sweet Grass once previous, delivering boats to Edmonton. Wanted to reenter north of Babb on hwy 2 and 89 but was dispatched a different route. I envy you, beautiful country. Circuit Rider:cbpour:

[waksupi]

Montana Charlie, The many posts I've read of yours assures me, you know of which you speak. I will try that method and report back. I understand about some shooters ignoring the sweet spot and using the same location on the barrel each time. As an aside, I entered Alberta at Sweet grass Nov. 5th '08, delivering boats to Whitehorse in the Yukon. Had only been thru Sweet Grass once previous, delivering boats to Edmonton. Wanted to reenter north of Babb on hwy 2 and 89 but was dispatched a different route. I envy you, beautiful country. Circuit Rider:cbpour:

You REALLY don't want to cross at Babb. Training station for both countries, and you will most likely be detained, vehicle searched, and inconvenienced in general.

[Boz330]

Most BPCR barrels are usually much stouter than a standard HP rifle so it wouldn't seem to be as much a problem. This is not scientific by any stretch of the imagination but I have found on a number of barrels of different lengths that the null spot seems to be very close to 8 inches back from the muzzle. I use Charlie's method and a hardwood stick. It is really easy to tell when you get the right spot. I have done it for a number of folks. I HAVE not done any experimentation to see how much difference it makes, but it can't hurt, or at least I don't think it can.

Bob

[Circuit Rider]

Waksupi, Retired in Jan., but still nice to know. I had stopped at Cabela's on the way out and picked up a couple pounds of smokeless powder for my FNA1. Would probably been in deep dodo if I'd come out that way. As I told Charlie, I envy you guys. Circuit Rider:castmine:

[405]

Gotta agree with MTC... several good points posted there.
Barrel harmonics vs accuracy is an art unto itself. I know that some BPCR shooters find the nodes and nulls along the barrel by putting a layer of baby powder along the top flat then shoot a round. The distribution of the powder after the shot may reveal the nodes, nulls along the barrel. Then pick the null as a point to rest on.

Dunno, about all that... predicting the sweet spot seems pretty complex to me. I've just used trial and error in finding the best front rest location. Then, shoot enough to verify the repeatablility. It seems on my Shiloh Sharps 45-70 with standard weight oct 30" barrel shooting 440 gr bullets to about 1100 fps the best place for front rest is on the forend just behind the cap. On my C Sharps 45-110 with 32" heavy oct barrel shooting 480 gr bullets to about 1200 fps the best place for front rest is on the barrel about 2 inches in front of the forend cap. Seems to hold true for both a regular sand bag rest and crossed sticks.

[Don McDowell]

Agree with 405, lots of variables. Not to mention stick stability, and shooter comfort, and sitting position.
Only way to find out what works for you and your rifle is try em all and then repeat over and over until it all comes together.

[wills]

http://www.longrangebpcr.com/Sweet.htm

On the other hand I recall reading you can put talcum powder on the barrel, fire a round and examine the powder to find the vibration node. I have not tried it. If I find the link to the source I will post it.

Here it is;

http://shilohrifle.com/forums/viewtopic.php?t=13765



Quote:
How do you go about finding the so called NULL of a barrel?

Joel, there are several ways:
1. Buy the Tuner Hardware and Software to make the measurements ...
http://www.varmintal.com/atune.htm
Finite Element Analysis on complex vibrations of a rifle barrel tuner using the LS-DYNA Finite Element Code.

2. Hang the rifle vertical holding the butt stock with the forearm off. Start knocking the barrel with a small dead blow or lead hammer .... Bing - Bing - Bing - Bong - Bing - Bing. When you hear the Bong, that's the Null Point

3. With an octagonal barrel, sprinkle talcum powder along the top flat. Shoot the rifle off hand. Look at the powder: you will see it lined up like this >>>>>>>>>>> X <<<<<<<<<<<< . The X spot is the Null point. Shoot several more Off Hand to verify
...

[KCSO]

My cross sticks for years were made with a leather sling between the sticks so the gun rested in a leather pocket rather than on sticks. I also shot my guns enough that i knew where to rest each gun for the best accuracy. On one rifle it might be at the entry pipe and on another 2" behind the muzzle cap. This takes a lot of shooting and expirimenting but it will pay off at the range. I was able to score well on cross sitcks many times and have shot more than a few mid to high 40's groups at 100 yards. The best advise I can give it to take out your rifle and SHOOT, a LOT.