Bmag accuracy improvements.

[gsperaz]

For those who have a Bmag and struggling with accuracy issues, take a look at my improvements on rimfire central thanks to a fellow shooter.
http://www.rimfirecentral.com/forums/showthread.php?t=530591&page=4

[EdKin]

Interesting will have to give it a try.

[scope eye]

I still can't wrap my head around why it works, it goes against everything we have learned.

Dean

[Crockett]

Could you let us know what size o rings those are? that way I don't have to guesstamate when I go to the depot tomorrow

[scope eye]

1/2 inch

Dean

[gsperaz]

Could you let us know what size o rings those are? that way I don't have to guesstamate when I go to the depot tomorrow
The O-rings were 5/16'' ID. I don't know the OD. It was an assortment box from advanced auto parts.

[gsperaz]

I still can't wrap my head around why it works, it goes against everything we have learned.

Dean

I'm not sure either, my other rifles are true free floating barrels. But they are also much heavier dia. barrels. I read that with thin barrels, shooting high pressure cartridges the barrel acts like a guitar string when fired. A harmonic vibration occurs that effects the bullet as it leaves the barrel.
The o-ring dampens the harmonics. That's all I know, but I'm glad I to have made a good improvement to my Bmag. I was ready to sell it, trade it or break it....

[shagerott]

It would be interesting to get a slow motion video of the barrel, magnified, to see how much it is moving. It reminds me of a video animation of barrel harmonics I saw on a website some time ago. Glad you found a way to tune it. Thanks for sharing!!

[gsperaz]

1/2 inch

Dean

1/2" were a bit loose, I think 3/8" work equally well.

[scope eye]

I took them out of the half inch bin, I did not measure them they were probably put there, like folks put back nuts and bolts in the bins at the hardware store. LOL

Dean

[Crockett]

Thanks. off to the depot in the am!

[gsperaz]

Good luck guys, hope to see some good results.

[Yankee]

I have a BMAG on the way so i am following this closely.

I really hope i don't have to go through this stuff, but something tells me i'll be buying plastic filler and o-rings. Silly rimfire only hunting laws....

:apathy:

[plinkin]

I'm not sure either, my other rifles are true free floating barrels. But they are also much heavier dia. barrels. I read that with thin barrels, shooting high pressure cartridges the barrel acts like a guitar string when fired. A harmonic vibration occurs that effects the bullet as it leaves the barrel.
The o-ring dampens the harmonics. That's all I know, but I'm glad I to have made a good improvement to my Bmag. I was ready to sell it, trade it or break it....

Every barrel experiences a harmonic "distortion" and not every barrel experiences the same. A friend told me if you clamp an action in a vice & hang a wire coat hanger on the barrel and lightly tap it with a brass hammer the hanger will move to a spot where the harmonics cease. He also stated it is different for every barrel. I believe he told me to mark the barrel where the hanger stops and that is the place you can have the stock & barrel meet. Not every barrel needs to be free floated. Many of the older Marlin rim fire bolts benefited from placing a shim between the stock & barrel. Both my rim fire Strikers have a non floating barrel and they are wicked accurate. Currently my 503 HMR produces better groups at 50yd than my 93r17

[gsperaz]

Good info, thanks Plinkin.

[n4ue]

About 6 months ago, I tried a similar 'trick'. I placed 2 pieces of rubber fuel line in the forend. The tops were cut in a "V" shape to position the bbl in the center of this pos stock.
I tried several groups with the tubing, then without, again and again. Group size was the same. Only change was POI change.

As an additional comment, I taught a new shooter to fire a rifle yesterday. I picked my M25 in .17 Hornet. I had almost forgotten how sweet a little ctg it is! And it's reloadable to boot.

The BMag has been a big disappointment.

ron

[gsperaz]

n4ue, I tried fuel line as well without any success. The O-rings in my current set-up make just a slight contact between the barrel and stock. The fuel line I used was wedged between the barrel a stock pretty firm and did not allow the stock to flex at all.
With the O-rings, I can still push on the stock and flex it against the O-rings.
Try it, nothing to loose but a few O-rings. I was a none believer at first until I found the sweet spot.

[n4ue]

Gsperaz, OK. I'll try the o-rings. I have 2 of the 'kits' with a wide selection of o-rings, both SAE and Metric....

As you said, nothing to lose......

ron

[gsperaz]

Here's where I ended up, maybe start here and see how it works for you.
http://i1097.photobucket.com/albums/g345/gsperaz/WP_000395_zps93eb5ac7.jpg (http://s1097.photobucket.com/user/gsperaz/media/WP_000395_zps93eb5ac7.jpg.html)

[gsperaz]

I have been amazed at the results....6 shots, 50 yds. 25 grain ammo.
http://i1097.photobucket.com/albums/g345/gsperaz/WP_000391_zps218f40d9.jpg (http://s1097.photobucket.com/user/gsperaz/media/WP_000391_zps218f40d9.jpg.html)