Testing of Rogers Muzzle Device

[Cabin Mike]

Spool picture

Here is a picture of the Spool & Spoolie sections.

Mike Sherrill

 

[steve]

I like it, Kinda looks like a blunderbus (sp?).

 

[Joe Friedrich]

Thanks Mike for the picture. I will assume weight can be added to the end of the spool?

Roger, very creative, looks real nice. What's the length of the sections if you don't mine me asking?

Joe

 

[Fred J]

Total weight

Roger:
What is the total weight of the spool as pictured?

 

[RvA]

Joe, yupper weights can be screwed right on the end of the spool section.

-----

Fred, the spool and the 3 extensions weight 3 1/2 oz

 

[chisqr]

I'm not sure if I understand something: how do external conditions, such as temp, altitiude, ect. influence the vibrations of a barrel, and - if so, are they large enough to induce a change on a target, or more seen in a calculation on a computer?

I have wondered this, and thought that a barrel in tune stays there.

Would a tuning fork change it's pitch when moved about the country?

?

s.

A tuning fork will definitely change it's pitch when temperature, air pressure, and humidity change. All these things affect the speed of sound in air with is connected to the oscillation frequency (pitch). But only the temperature is going to have much of an effect on the phyiscal oscillation frequency of the tuning fork itself. That's the critical part related to barrel vibration.

Because of this, the frequencies of tuning forks used in laboratories are specified at a particular temperature.

For any physical system, natural vibration frequencies are dominated by the length and the mass of what is vibrating. Temperature affects the length and also the speed of sound in the metal.

Barrels are a lot more complicated though because the effective vibration length is affected by points of contact or attachment with the rest of the rifle. It is conceivable that to the extent things like humidity affect, say the stock, it could have an influence on the vibration of the barrel.

How much of a change these things might produce at the target is a much more difficult question that is probably best answered by testing. But they can have an effect in principle.

Temperature is probably the dominate weather factor, and it's effect on the length of a barrel is pretty easy to calculate. Even so, the change in length is pretty small.

 

[RvA]

chisqr,

I was thinking about that when I made my reply to Steve, but I don't think the overall length change in the barrel would be great enough to effect the tuning. I mean in the range where shooting these rifles, let take an extreme -20 to 110 how much will the barrel really change? A couple of tents at best? I'll have to dig out the books and do the math to be sure but it can't be much. I think the temperature effect on the ammo will be a much larger factor to deal with.

Best,

Roger

 

[Vibe]

chisqr,

I was thinking about that when I made my reply to Steve, but I don't think the overall length change in the barrel would be great enough to effect the tuning. I mean in the range where shooting these rifles, let take an extreme -20 to 110 how much will the barrel really change? A couple of tents at best? I'll have to dig out the books and do the math to be sure but it can't be much. I think the temperature effect on the ammo will be a much larger factor to deal with.

Best,

Roger

Thermal expansion of steel is 0.00000645in/in/°F
So a 20" barrel will be 0.005" shorter at 40°F than it will be at 90°F - which is about 1/6 of a tuner (of "current" design) revolution using 32TPI. I believe that smaller adjustments have proven to have significant effects.
-20°F to 110°F is a 130°F change, or a 0.017" change in a 20" barrels length. 0.020" with a 24" barrel.

 

[steve b.]

ok, that makes sense..

so, let's say i have a 10.5lb gun built by meyers, and it is shootin good at his shop during the mid winter season, with temps in the 40's and below. he ships it off and now we're shooting it in vegas during the summer when it's 115 degrees. i'm assuming that the rifle needs to be retuned due to the change in temp?

meyers has built some nice rifles for a few of the guys down here, especially a wicked little sporter, and i wonder how to: 1 - identify the changes, and 2 - how to manage them, especially with a sporter.

anyhow, thanks for answering the first questions.!

s.

 

[chisqr]

I should have been more clear. I would have guessed that the practical effect of thermal expansion would be insignificant. I was just trying to give a direct answer to Steve b.

Vibe beat me to it, but I did what I thought was a worst case and assumed RvA's temp range, 316 stainless (which has a big coefficient for steel), and a 30 inch barrel.

The expansion coef. is 0.0000173 / deg C. This give a change in length of 0.037 inch.

With more reasonable temp. extremes, the proper alloy of steel, and barrel length it would be less.

In any case I would have thought RvA was right about the effect on the ammo being the biggest factor.

 

[RvA]

OK guys, it's been about 15 years since I did these calculation so bear with me.

From the info I can find Barrel steel (416) has a CoE of 5.5 and Alum 25.

So if we take a normal 26" Barrel and go through the extremes of -20f to 110f we end up with a growth of 0.0103" for the barrel. Now lets not forget our little deivce on the end of this tube is going to change too. So if our aluminum device has a free length from the muzzle of 3" it will grow .0054" so we will in effect have a change of 0.0049" to deal with. That would be 5 clicks on a Hoehn tuner.

From experiences that’s not enough change to worry about.

Best,

Roger

 

[Vibe]

From the info I can find Barrel steel (416) has a CoE of 5.5 and Alum 25.

Check

So if we take a normal 26" Barrel and go through the extremes of -20f to 110f we end up with a growth of 0.0103" for the barrel.

I got 0.01859" for that set of conditions and extremes. That's a significant difference.

Now lets not forget our little device on the end of this tube is going to change too. So if our aluminum device has a free length from the muzzle of 3" it will grow .0054"

Again I came up with a different result of 0.0975" for the alum.

so we will in effect have a change of 0.0049" to deal with. That would be 5 clicks on a Hoehn tuner.

I'm really confused as to how you got a smaller number here than either of the other components. Added together we would have 0.02634" Or as you put it in terms of clicks @1 per 0.001" 26 clicks.

From experiences that’s not enough change to worry about.

Best,

Roger

I had heard several people say that 5 click would take them from in tune to out, 25 would take them in,out,and back to somewhere else, possibly in or out.

 

[RvA]

Vibe,

I subtracted the tuner growth from the barrel growth to come up with that smaller number, why because, the tuner is beyond the muzzle and as the barrel grows the node is going to move along right with it. And being the tuner is beyond the muzzle it's effect will be even more pronounce then when the tuner is in its cold state from the increase in its cantilever effect on the barrel.

Now could I be full of hot air.... could be. But it worked in my mind’s eye. I mean we could really get nuts with this theory Vibe, but what really matters is when the bullet hits the paper. That’s the real deal, and from what I've seen so far from the testing Mike and I have been doing I'm on the right track with this design. Would it be nice to have the “Why” it’s working sure, but I know I don’t have the equipment or the cash flow to even begin to measure what’s really going on here. So I take the results I see at the target and go from there. What else can we really do?

Best,

Roger

 

[Vibe]

as the barrel grows the node is going to move along right with it.

You could be right in that. But at this point I'm not quite ready to take it as a "Given".

And being the tuner is beyond the muzzle it's effect will be even more pronounce then when the tuner is in its cold state from the increase in its cantilever effect on the barrel.

This, on the other hand, I will take as a "Given" could be good or bad. We'll have to see what extended testing in those conditions reveals.

from what I've seen so far from the testing Mike and I have been doing I'm on the right track with this design.

I fully agree and am rather excited to see how it plays out.

So I take the results I see at the target and go from there. What else can we really do?

Best,

Roger

Keep up the good work

 

[Cabin Mike]

Update on testing

To All, I was able to continue my testing of Roger's Muzzle Device this past weekend. I started out with my last weight sequence combination of spooly, spooly, spool, & 1/2 oz aluminum cap (see picture below). I was able to re-produce the same results & accuracy that I experienced the previous testing session. This makes me feel like we are on the right track since we are getting repeatability on different days with similar conditions.

I feel that each testing session is giving valuable information and have a few more ideas to try, hoping to find the very best combination possible. I have found something that seems to be enhancing the results in a positive manner and will be pursuing it in my next testing session. I have discussed all of my findings to date with Roger & Bill and we all feel that it is best to wait until we have had a chance to prove some of our past findings as well as our future results before posting the final results. Roger wants to be able to offer this Muzzle Device in a final version when he releases it.

Mike Sherrill

Spooly, Spooly, Spool, & 1/2 oz aluminum cap weight

 

[Gene Corvin]

Well I'd say James turned down tuner will work the same way, over on another site I saw pictures of you Timing Method , when the rifle ended up in Time you had an extra 11oz. of weight on a Harrel tuner, so it looks like you've turned a full 360 degrees in about a year, so when someone else changes a little something don't be so hard on them.
>
FA

Foster,
You know when a man has been tuning on his rifles for over a year and still has not finished it's no wonder he can't believe that it can be done in fifteen minutes!

 

[tonykharper]

Gene, Foster, you fellas are down south and will see shoots before us up north. after they take the targets down look at the fouling shots, one shot goes awry and then settles down??? the rifles tuned and probably has a von ahrens tuner. if the fouling shots string all over the place this is real simple the tuner cannot adjust for varying velocities. it's not rocket science just common sense............

Talking about commmon sense ------ why does the first shot out of your perfectly clean barrel go awry?

 

[jGEE]

Condensation can start forming inside the bbl in just 2 or 3 min. The first shot could be the bbl has been sitting for days or even just 30 min. A dry path then start shooting?....... I think the weather you shoot in has a lot to do with how fast moisture form in your bbls... More humidity the quicker you get a "wet" bbl .... yep i know i am a rookie and Tony shoots matches.. joe

 

[jGEE]

Martin , you must have slipped that RVA tuner advice by unnoticed last year,and the second and third best opton advice too.
I'm sure the RVA will work just like the turned down Harrel,or the 8oz.Harrel or the 8oz.with a noodle,or all of them with one or two mid-barrel
tuners added. they're to many different combinations out there on WINNING for everyone to be wrong.
your way this year? my work for you and a few others, but it's not the ONLY WAY and it looks to me that's what you're trying to say in all these posts, if it's not your way it's wrong?
I'm going to let you in on a little secret just between you and me, about 90% of this rimfire game is about the best AMMO you can get and it always will be. tune all you want if you don't get GOOD ammo your just spinning your wheels. now keep that to yourself if you tell anyone I'll deny it!
>
FA

Not to spoil anything and i sure don't remember who said it but ammo is 90% rimfire -maybe more.

A lot of people shoot rimfire because they can afford it........ cheap ammo. The good ammo has gotten out of reach for me and a lot of others......

The tuning myth: Maybe it is true, maybe not.... Maybe ever one has it right, maybe everyone has it wrong. There have been a lot of great shooters come before me - i mean a lot better than i ever will be.

I shoot SK standard plus 95% of the time- economic reasons. What if there is some "magic tune" that will make 30feet per sec ammo shoot? PROBABLY NOT BUT WHAT IF.......... joe

 

[Slick Willy]

Foster,this year Charlie Scott shot 2500 and a 2450 back to back after two guys from OK gave him two boxes of Team 2115,they knew it was Killer and it almost cost them,that`s just one of many tales of " It is the Ammo Marty"! They wanted to prove a point and did. I think Charlie`s rifle was tuned!