Most Probable Cause of these Flyers??

[BoydAllen]

How are you guys addressing your rifles? Holding them? How much of a hold?

I have a friend that shoots Benchrest (1-200 yd.) and he was having a problem with fliers . I told him that based on what he was telling me, that his bags were too hard. As a temporary measure he tried a soft rear bag, and since he didn't have anything but heavy sand, he filled it with sawdust case cleaning medium. It worked, he shot small groups. A few days later he went to a match, and on the first day had the same problem, using his original harder bags. After the first day, he changed to a front bag that was of the inexpensive unreinforced Cordura variety, softer than what he had been using. The problem went away, and on the second day he took sixth place. I see it all the time, fellows misunderstand the complexity of the issues, ignore important issues if favor of concentrating on the load. Good luck with that. It's kind of like trying to fix your high speed mixture by fiddling with your idle stop.

 

[Tozguy]

Boyd, your point is well taken, tuning bags has had an important impact on reducing dispersion for me too.

But 'To a hammer, every problem looks like a nail'

 

[rocketron]

Boyd

what would you suggest filling the front bag with?

Ron

 

[artbosco]

Looks like I have a long list of potential causes to work on...

First, look at the simplest one to fix.
Here's what I'd review:
http://benchrest.netfirms.com/Filling%20Sandbags.htm
before all other possibilities, because it's the easiest to evaluate. And, because Speedy [Benchrest Hall of Fame Inductee] knows what he's talking about.

For sure I am going to change the hard 3" nylon lobe style bag. The sand in it is thin and hard. I have a leather Protektor style bag from another rest, but I suspect it is a bit too narrow. Plans were to make a Protektor style bag from upholstery weight Microfiber, somewhat similar to SEB ones below:

Not sure what to use in them.

Use Hart's Parakeet gravel and play sand 50/50 in the front rest, as recommended by Speedy. http://benchrest.netfirms.com/Filling%20Sandbags.htm It works great. For the rear bag, same thing in the ears; Heavy Sand in the base of the bag.

Don't beat yourself up trying to Jerry-Rig a bag. Sinclair's got the Protektor Cordura for $17.95. A bargin.

Scan down this page: http://www.sinclairintl.com/.aspx/pid=33243/Product/Protektor_Owl_Ear_Front_Bags

The material used in the Seb in my opinion [I've got two sitting on my shelf] isn't as great as some may suggest. But, you've got to try different material to see what you like. Good Luck!

 

[RonAKA]

I would like to thank all who responded with suggestions. I've summarized them as best I can below, in no particular order, other than grouped as to type. The plan when the weather cooperates is to work my way through these from the easiest to do, to the harder ones last. I'll will bookmark this thread and try to remember to update it with the results. Will be a while as we still have about 3' of snow, with more coming down today...

Technique
- Fatigue, flinch
- Shoot targets in vertical direction, not across to avoid BR top twist
- Keep pistol grip clear of rear rest rabbit ears
- Zero parallax

Rest Equipment
- Front bag too hard (switch to softer bag with 50-50 mix of sand and Hart's Parakeet gravel)
- Rear bag, not hard, but not rocking either

Loading
- Identify brass that resulted in flier and inspect
- Change grip on bullet with seating depth, neck tension, and graphite lube
- Try different primer from BR-4, 205M?
- Measure loaded rounds to determine neck clearance by cartridge – need to neck turn?
- Do ladder at 100 to see if vertical is minimized the same as 300.

Gun/Scope
- Action screw torque, bedding - resistance to action/barrel twist
- Loose reticle causing double group?
- Savage suggested by Tozguy – Tape over the name?
- Install 3” stabilizer block
- Shoot 10 shots without cooling to see if heat is causing flyer

 

[RonAKA]

LRPV stock? Never had one myself. Is it bedded?
I do know the LRVP comes with some texturing to the stock. At least in the forearm.
Thats not good for riding the bags.

Yes the action is bedded. The LRPV comes with a HS Precision stock with an aluminum bedding block. I skim bedded with Devcon. I initially had the action screws bedded too, but was convinced to bore out the holes to give some clearance. If anything I've had more flyers since boring out the action screw holes. So I do wonder if I'm getting a bit of twist movement in the stock. I do my torquing by feel, and plan to get an in-lb torque wrench to try and control that better.

Yes, the stock is textured. I removed the sling swivel mounts, and before each session put some plastic packing tape on the stock where it contacts the rests, and apply a bit of silicone lube to the tape.

 

[RonAKA]

I question the quality of the rest top, and those bags offer no consistant shape....too flimsy. Do you pound the base into the bench (if wood). Are you sure ALL adjustment screws are tight.....Make sure there is plenty of daylight under the rest feet.

Yes, I've known for a while the front bag is not great. Will replace it. The bench I use is poured concrete, so no pounding. I level the rest using the sharp feet. Will have to check to see I'm getting lots of clearance, but I think so. At one point in the season I did find an adjustment screw loose, that was causing some movement in the whole top base. However, after I tightened it, there was no noticeable change in the groups...

 

[Tozguy]

Ron,
With my Rock BR the two front screws have to be tightly locked after the rest was level or it will show up in the grouping. Also, when adjusting elevation with the rear screw, the crosshairs would wobble sideways on their way up or down. The adjustment screws fit very loose by my standards. Locking the rear screw after adjustment would throw it off. So I installed a screw with a nylon tip through the side of the foot to put tension on the rear adjustment screw. Now it doesn't need to be locked and it doesn't squirm.

 

[LHSmith]

Ron,
With my Rock BR the two front screws have to be tightly locked after the rest was level or it will show up in the grouping. Also, when adjusting elevation with the rear screw, the crosshairs would wobble sideways on their way up or down. The adjustment screws fit very loose by my standards. Locking the rear screw after adjustment would throw it off. So I installed a screw with a nylon tip through the side of the foot to put tension on the rear adjustment screw. Now it doesn't need to be locked and it doesn't squirm.

Toz's problem with the rear adjustment screw actually mirrors my problem with a poorly machined speed screw as I posted previously. Those threads on the rest feet are awful course (and on a Chinese rest I'd wager there no better than Class I grade) and it doesn't take much slop to show up on the target.

 

[Tozguy]

We are on a roll Mr. Smith. The OEM foot screws are 3/8 NC thread with a sloppy fit in my Rock BR. In addition to adding a tension screw in the rear foot I made a second screw using a 3/8 NF screw. It was a simple matter to tap the finer threads right through the coarse ones. The finer screw is used for shooting at 200 yds and the NC screw for 100 yds. Works like a charm.

 

[LHSmith]

We are on a roll Mr. Smith. The OEM foot screws are 3/8 NC thread with a sloppy fit in my Rock BR. In addition to adding a tension screw in the rear foot I made a second screw using a 3/8 NF screw. It was a simple matter to tap the finer threads right through the coarse ones. The finer screw is used for shooting at 200 yds and the NC screw for 100 yds. Works like a charm.

Toz- So do you still use the lock nut on the rear screw? or hold the screw while you shoot? FWIW -when shooting off of wooden bench tops it is common for competitors to place a coin under the rear leg point in order to eliminate vertical that might show up from the leg point not settling in the same place shot after shot.

 

[Tozguy]

LH,
The screw points are usually thumped hard into a wood bench. The tension screw that bears at 90 deg. to the rear screw is set with enough tension so I don't have to lock it. The points were checked for concentricity and don't seem to move from shot to shot.

 

[BoydAllen]

One way to make the wiggle in the front two points go away is to put a thin jam nut on the underside of the legs, and tighten it with a small wrench, after leveling the rest. If the rest is heavy enough, and the front two points are secure, I don't see how clearance at the rear screw could let the rest move.
Boyd

 

[LHSmith]

One way to make the wiggle in the front two points go away is to put a thin jam nut on the underside of the legs, and tighten it with a small wrench, after leveling the rest. If the rest is heavy enough, and the front two points are secure, I don't see how clearance at the rear screw could let the rest move.
Boyd

In my case, I had a speed screw that although turned to put crosshairs on target would drop further upon recoil.....I have heard the term "histeresis" used to describe this. This particular make of speed screw was known to be problematic occasionally amongst the BR crowd here in the NE. I solved the problem by using lapping compound on the coarse adjustment threads.
Boyd, you are correct about a heavy enough rest "should" negate any thread slop....as I remember it, my son was using an Aluminum Bald Eagle rest with "bad" speed screw and a 10# VH gun when this problem showed itself. At the time I was using a Cast Iron Bald Eagle rest with speed screw and a 13.5 gun with no problems. Notice I said "should" above, but after my experience I can see where Toz's rest movement problems could come from that thread slop causing it to drop under recoil.

 

[BoydAllen]

How did you isolate the drop to the screw, with other potential sources? Do you have return to battery bag rifles?

 

[LHSmith]

Boyd- I just dug out the speed screws ( haven't use them for 3-4 years), and apparently the bad one still does that dropping thing. I do know that some smiths know how to correct the problem , but I opted to go to a Farley ( for VFS) and Shadetree for VH. I have read that it might be the center post that is the problem. There is one point in it's travel that drops and sounds like a pen clicking.
How we found the problem? ..... he kept getting low flyers, 9-ring/ 8-ring I knew there were problems with them in the past, don't remember how my son confirmed it, but upon close inspection we could repeat the drop. I would fault the light-weight rest for not showing the drop until recoil.

 

[BoydAllen]

Interesting
Thanks

 

[jo191145]

A qick fix on the Caldwell rear screw is installing a big rubber washer in between the jam nut and base. Keeps those sloppy threads under considerable tension and you need not lock/unlock the screw. Not perfection but much better than stock.

 

[RonAKA]

Ron,
With my Rock BR the two front screws have to be tightly locked after the rest was level or it will show up in the grouping. Also, when adjusting elevation with the rear screw, the crosshairs would wobble sideways on their way up or down. The adjustment screws fit very loose by my standards. Locking the rear screw after adjustment would throw it off. So I installed a screw with a nylon tip through the side of the foot to put tension on the rear adjustment screw. Now it doesn't need to be locked and it doesn't squirm.

Interesting. I've never considered adjusting elevation with the feet screws. I just adjust the rest to level, lock them, and leave them alone after that. If you adjust elevation with the rear foot, how do you keep the rest level? Or, do you just not worry about it?

 

[LHSmith]

It is common practice to adjust elevation with some sort of device in the rear leg to provide fine adjustment in these type of rests...it is usually much faster than turning the mariner wheel and usually a much finer adjustment. Another option that is used is the "bag squeezer" method where you manipulate the rear sandbag with your oft hand. Yes, some purists do argue that varying elevation alters the fore-end contact with the front bags....in essence you are tilting the bag .This is why coaxial rests have such a following.
Having said this, remember I am a score shooter and I must traverse a target (100 yd specifically) where each bull is ~6" apart or worst case ~12" (between upper tier and lower tier bulls), so the inter-rationship between rifle and bags is important....my favorite BR tenent: " keep EVERYTHING consistent from shot to shot."
It takes very little movement in your rest system to cause a bullet hole of dispersion.