Optimal 22LR Barrel Length

[rick137]

Long barrel vs short barrel.
If a scoped rifle, shouldn't be any difference in accuracy.
I can't see barrel length affecting mv spread.
Coefficient of friction applies the same in both cases.
Longer barrel should produce lower mv's.
MV spread is cartridge caused, not barrel length.
The longer the time of flight, the more vertical spread produced.
ES vs SD...SD let's you know what 2 out of three shots will do, on average.
That third shot is going to be outside the average.
ES is what loses competitions.
In a match, tight ES is needed to win.
That one stray can turn a 250-10X into a 240-9X, you lose.

Justin:

One is on thin ice stating anything definite about the coefficient of friction. To wit, from Wikipedia,
"While it is often stated that the COF is a "material property," it is better categorized as a "system property." Unlike true material properties (such as conductivity, dielectric constant, yield strength), the COF for any two materials depends on system variables like temperature, velocity, atmosphere and also what are now popularly described as aging and deaging times; as well as on geometric properties of the interface between the materials, namely surface structure.[1] For example, a copper pin sliding against a thick copper plate can have a COF that varies from 0.6 at low speeds (metal sliding against metal) to below 0.2 at high speeds when the copper surface begins to melt due to frictional heating. The latter speed, of course, does not determine the COF uniquely; if the pin diameter is increased so that the frictional heating is removed rapidly, the temperature drops, the pin remains solid and the COF rises to that of a 'low speed' test.[citation needed]"

Suppose the COF is velocity dependent? About all one can say, or at least all I would say, is the MV depends on the details of the energy released from the charge and the details of the COF over the entire length of the barrel.

Rick

 

[justin amateur]

Thanks Rick...been a long long time since college engineering classes.
More reading to do. Ought to keep me busy.

 

[rick137]

Thanks Rick...been a long long time since college engineering classes.
More reading to do. Ought to keep me busy.

Justin:

Always a pleasure. Another factor possible significantly affecting COF came to mind. The hardness of the bullet. The issue is not only identifying the factors but much harder quantifying them so know if one dominates, or two are equally significant or whatever.

On the other hand there is the anecdotal evidence, stating something without data properly analyzed for statistical significance and proper experimental design. Who knows, maybe some of it is actually true. Usually interesting reading.

Your approach is right-on since so many variables. Keep as many of the variables the same as possible and do the experiment.

Rick

 

[nakoa01]

Then on what are you basing your disagreement? I've proven my statements with dozens (many dozens) of other rifles, using same lot numbers of ammo. This is including several rifles I've cut down to 16" which started out with 28" barrels. Long barrels tend to have reduced ES. It's a fact, and one that's been confirmed for me over 20+ years of pursuing precision rimfire.


I'd need to put some work into cataloging rifles comparatively in order to produce that data. I've only ever been really concerned with each rifle on its own, which is why I don't have a big chart showing the dozens of rifles I've tested and their respective velocity data. On rifles I've cut from 28" to 16" (only about 3-4) I've seen between 8% and nearly 40% increase in ES with the respective lot number I was shooting in those rifles at the time. A lot of this was early on, and I hadn't drawn the correlation between barrel length and ES yet. It was during work with those rifles that I began to notice it. I just kind of arbitrarily assigned a "25% worse" ES at 16" than 28" value in my head to simplify things for me.

Another point of note, is in those rifles I cut down to 16"... they shot worse at 16" than they did at full length. All of them. Some to a much higher degree than others.

Fellas, I didn't intend to conquer the argument with a couple of sub-10min videos. However, this concept is all settled for me. I understand some of you want more "proof," and my suggestion is to get to work. Bust out those chronographs and chop saws if you want. I have a lot of other things that I'm testing which I don't already know the answer to which are more important for me to work on right now. That may seem harsh, but I have limited time and I can't spent it going over things I already know in order to "prove" something to the internet. Even if I did, many will want to just argue about it anyway... since unreasonable people and trolls are basically the majority now. I never know who is genuine and who is a waste of time. So that's why I've shifted to simply providing short videos that mildly demonstrate the concept, rather than trying to go all-in on convincing people of the truth. No one seems to care, and point in fact... the more resolute my position and persuasive my arguments, the more people resist the truth. So frankly, I've stopped trying to convince people, and instead have taken the approach of "here it is, be ignorant if you want."

It's about time first hand experience makes a come-back. So don't listen to me either. I'd prefer people to do the work themselves so they can actually KNOW something instead of just regurgitate what they see/hear and pass it off as their own.

Orkin, watched your videos. SUPER INFORMATIVE. Good stuff thank you.

 

[Sagittarius]

All I know is I like a 24" barrel with a tuner attached for 27" total.
After shooting with a tuner, I will never again order any 22 rimfire rifle without one!
I don't have enough experience or expertise to argue barrel lengths on this forum so I will get what aesthetically pleases me and the above combo is it.

 

[beetroot]

I've been intrigued by this thread and have been meaning to test the theory for myself, finally did so today.
I shot my 22" CZ American and my 16" T1x with both CCI Standard velocity and SK Match.
It would seem my results back up the theory, with both lots of ammo showing slower speeds but lower ES and SD in the longer barrel CZ.
Results were as follows:
CCI STD T1x: Ave 1059fps, ES 46fps, SD 12
CCI STD CZ: Ave 1026fps, ES 37fps, SD 10

SK Match T1x: Ave 984fps, ES 116fps, SD 35
SK Match CZ: Ave 971fps, ES 85fps, SD 27

Most surprising was crappy the SK match did, the last lot I had was extremely accurate out of both rifles but this lots seems a bit rubbish.
Groups were better with the CCI STD too.

 

[Gleedus]

Very interesting thread. I also am a strong believer in testing. I shoot mostly 22lr and compete in PRS, CRPS and a lot of people say that 16" is the best barrel length because it gives the highest velocity. My question is where is the evidence? With semi yes that is close but with bolt guns like the majority of us run my research would indicated 20-21" gives max velocity with most ammo.
And if long barrels are so bad why do the benchrest guys run them? Trying to find out why benchrest runs long barrels was difficult because that crowd tends to not share from my experience. (Maybe they dont even know and its hand me down info as well same like we get?) The conclusion I came to was reduced velocity spreads which for me is a big deal because velocity effects the drop of a 22lr bullet at long range significantly. So I ordered a 26" barrel. Now I can have better balance for field shooting improved ES. All in theory as I'm still waiting for it to show up. Then @orkan comes on here and says hey this is what I've learned. We can take it or leave it but it shows something that i really appreciate about the practical shooting community guys share what they learn freely!

 

[1813Benny]

Very interesting thread. I also am a strong believer in testing. I shoot mostly 22lr and compete in PRS, CRPS and a lot of people say that 16" is the best barrel length because it gives the highest velocity. My question is where is the evidence? With semi yes that is close but with bolt guns like the majority of us run my research would indicated 20-21" gives max velocity with most ammo.
And if long barrels are so bad why do the benchrest guys run them? Trying to find out why benchrest runs long barrels was difficult because that crowd tends to not share from my experience. (Maybe they dont even know and its hand me down info as well same like we get?) The conclusion I came to was reduced velocity spreads which for me is a big deal because velocity effects the drop of a 22lr bullet at long range significantly. So I ordered a 26" barrel. Now I can have better balance for field shooting improved ES. All in theory as I'm still waiting for it to show up. Then @orkan comes on here and says hey this is what I've learned. We can take it or leave it but it shows something that i really appreciate about the practical shooting community guys share what they learn freely!

One of the reasons for longer barrels in RFBR is the use of tuners. Longer barrels with a straight profile (OD approx .875-.900") are able to be successfully tuned to a high degree of success. Shorter stiff barrels do not respond to tuners and thus are not in favor.

 

[Gleedus]

One of the reasons for longer barrels in RFBR is the use of tuners. Longer barrels with a straight profile (OD approx .875-.900") are able to be successfully tuned to a high degree of success. Shorter stiff barrels do not respond to tuners and thus are not in favor.

I never considered that aspect. It does make sense.. Im not sure I would want to run a tuner for prs but a few of the guys around here are with good success. I opted for a 1.063 straight as I am getting the duece and that is the tendon size and they dont run a barrel nut. So trying to get a stiff long barrel.
Do the RFBR guys not go bigger then .900?

 

[1813Benny]

I never considered that aspect. It does make sense.. Im not sure I would want to run a tuner for prs but a few of the guys around here are with good success. I opted for a 1.063 straight as I am getting the duece and that is the tendon size and they dont run a barrel nut. So trying to get a stiff long barrel.
Do the RFBR guys not go bigger then .900?

.850-.900" OD seems to be the optimal range for RFBR with tuners, however there are always some slightly larger, some smaller profiles. Many don't go over .925".

Regards,
ken

 

[Gleedus]

.850-.900" OD seems to be the optimal range for RFBR with tuners, however there are always some slightly larger, some smaller profiles. Many don't go over .925".

Regards,
ken

Interesting... the guys around here with tuners for prs are .850-.900 normally from my observation but assumed that was due to the action. Thanks for chiming in.

 

[parshal]

I did some testing with a 20" barrel and 26" barrel on my Rimx with .223 suppressor and no tuner. Everything else was identical including lot numbers. All are 10 shot strings.

Here's what I found.

Date	Temp	Barrel	Manufacturer	Model	Velocity	SD	ES
10/9/2020	80	26	Eley	Edge	1070	17.4	51
9/24/2020	77	20	Eley	Edge	1103	8.2	25
10/9/2020	80	26	SK	LR Match	1052	9.8	33
9/30/2020	68	20	SK	LR Match	1094	7.2	20
10/9/2020	80	26	Lapua	Midas+	1012	8.3	20
9/30/2020	68	20	Lapua	Midas+	1068	8.3	26
10/9/2020	80	26	RWS	R50	1057	13.6	38
9/25/2020	84	20	RWS	R50	1127	10.1	35
10/9/2020	80	26	SK	Standard+	981	7.3	19
10/1/2020	61	20	SK	Standard+	1045	11.9	53
9/30/2020	68	20	SK	Standard+	1053	6.7	19
10/9/2020	80	26	Eley	Tenex	1063	11.2	27
9/25/2020	80	20	Eley	Tenex	1109	10.0	33

 

[littlepod]

My friend has a 20" MTU Vudoo, and I have an 18" Kukri Vudoo. Same Ravage chamber, and I get 4fps more than him. Center-X I clock in at 1090 and he clocks in at 1086.

 

[Gleedus]

I did some testing with a 20" barrel and 26" barrel on my Rimx with .223 suppressor and no tuner. Everything else was identical including lot numbers. All are 10 shot strings.

Here's what I found.

Date	Temp	Barrel	Manufacturer	Model	Velocity	SD	ES
10/9/2020	80	26	Eley	Edge	1070	17.4	51
9/24/2020	77	20	Eley	Edge	1103	8.2	25
10/9/2020	80	26	SK	LR Match	1052	9.8	33
9/30/2020	68	20	SK	LR Match	1094	7.2	20
10/9/2020	80	26	Lapua	Midas+	1012	8.3	20
9/30/2020	68	20	Lapua	Midas+	1068	8.3	26
10/9/2020	80	26	RWS	R50	1057	13.6	38
9/25/2020	84	20	RWS	R50	1127	10.1	35
10/9/2020	80	26	SK	Standard+	981	7.3	19
10/1/2020	61	20	SK	Standard+	1045	11.9	53
9/30/2020	68	20	SK	Standard+	1053	6.7	19
10/9/2020	80	26	Eley	Tenex	1063	11.2	27
9/25/2020	80	20	Eley	Tenex	1109	10.0	33

I like that...
My data base shows lapua and SK slowing down more with a long barrel then eley and it would appear that is for you too.
Now my question is what headspace on each barrel? Is it identical between barrels?

 

[parshal]

I'm not sure about actual headspace but the tenon on the longer barrel is 1.6835". That's length necessary to keep the bolt nose from touching. I measured the shorter barrel a while back but forget the exact dimension. It was within .002" of 1.6835".

 

[nakoa01]

Vudoo 16in .25inch gun
Vudoo 22in barrel right there with it
Vudoo 16in sporter barrel almost exact same results.

 

[FromMyColdDeadHand]

All I know is I like a 24" barrel with a tuner attached for 27" total.
After shooting with a tuner, I will never again order any 22 rimfire rifle without one!
I don't have enough experience or expertise to argue barrel lengths on this forum so I will get what aesthetically pleases me and the above combo is it.

One of the reasons for longer barrels in RFBR is the use of tuners. Longer barrels with a straight profile (OD approx .875-.900") are able to be successfully tuned to a high degree of success. Shorter stiff barrels do not respond to tuners and thus are not in favor.

Do you tune for ammo and conditions? Or do you tune for ammo and it works at regular temps? ie - do you have to tune everytime you go out?

On barrel length, which ones can you cut to length and which ones are meant to be shot at a specific length due to contrstriction? I know Benchmade ones are constricted and meant to be a certian length.

Does rifling have anything to do with the effect on speed over length? Barrel internal finish?

 

[D_TROS]

Do you tune for ammo and conditions? Or do you tune for ammo and it works at regular temps? ie - do you have to tune everytime you go out?

On barrel length, which ones can you cut to length and which ones are meant to be shot at a specific length due to contrstriction? I know Benchmade ones are constricted and meant to be a certian length.

Does rifling have anything to do with the effect on speed over length? Barrel internal finish?

Hey man hope you are well. Havnt shot with you in awhile!

Im no means an awesome or even good BR shooter but I have done it a bunch. Again with rimfire its alot of hocus pocus and unexplainables and MOSTLY getting an awesome lot of ammo and buying a ton of it.


-Hardcore BR guys will both tune for weather and ammo...mostly have ammo they know works for different temps and know what setting works best with that. Its not like they tune every time they go out but BR guys will, like us with load work up before a match, tune every lot of ammo before a match and keep grreat records on everything. day of match fine tuning the tuner is not uncommon to see if the actual weather might have a diff setting.

-barrel length is more vudu and some barrels have tight spots. most time the smith will check the barrel for any tight spots and adjust barrel length off that. as mentioned you do need a length that is more susceptible to the tiny variations that tuners add/subtract from - ie longer and thinner (shorter and thicker are less susceptible to tuners).

-most BR people are hardcore button rifled dedicated. there have been awesome results with cut barrels. more vudu but my opinion is the button riffling is less altering to a lead bullet of rimfire if that makes sense but again both kinds have had great success.


GL and see you out there soon! I havent shot at CRC rimfire in ages...need to.
DT

 

[chanrobi]

Vudoo tested this - 16-21" same velocity, above 21" bullet slowed down by barrel length

 

[Random One]

If barrel dwell time is the key factor for using a shorter barrel, then it seems to be a pretty thin argument, IMO. If I did the math right the difference in barrel dwell time between a 26" barrel and a 20" barrel - using the same round at say, 1050fps; is .00047 seconds less barrel time with a shorter barrel. That's roughly 5 / 10,000 ths' of a second.

There may be other reasons for one length over the other, but it aint' dwell time, IMO.

 

[GordonsGarage]

This has been an excellent read and I thoroughly enjoy everyone's discussions, I've learned quite a bit in this thread alone.
In my opinion it comes down to purpose of the rifle, if it's suppressed and it's a hunting or prs style gun 16-20" likely fits the purpose best, if all out accuracy off a bench is the goal then a 26" barrel in a 20 pound gun fits that purpose best.
I do see some advantage to the longer barrel potentially stabilizing the bullet some more and evening out velocities, if all out precision is the goal.