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Barrel temperature ?
- Thread starter Baddog 0302
- Start date
Big fella, a yes or no question is asked in a room of 30 people. You are the only person to raise their hand when asked if yes is the answer, 29 others say no...... Doesn't mean you are wrong, BUT you should probably seriously consider that as the most likely result and consider the fuck out of your reasoning before continually backing yourself.
Cheers
Pete
Late … but I found this thread researching heat not for the topic of barrel life but more for velocity and better forecasting cold bore POI vs running a stages during a hot active day or PRS.
Something stuck in my head a few weeks ago, was shooting w my kid the day before a match to check some speeds snd noticed our shot string increased velocity from shot 1 to shot 10 or so. It was 80 degrees outside.
I just want to be able to be able to forcast my elevation on a cold bore shot vs once I got the barrel hot. I’m considering using my barrel temperate in my velocity calculations on StrelokPro instead of just using air temperature in enviromentals.
If it’s 80 degrees outside and my cold bore shoots 2800 fps, I would like to know what’s going to happen to my velocity when that barrel starts cooking to 130 degrees. I’m thinking to leave the 80 degrees in the environment calculator for air density, however, I might try increasing muzzle velocity inputs as my barrel starts to resemble a furnace.
An IR laser thermometer might really help understand muzzle velocity better so you can get better forecasting and powder sensitivity.
Something stuck in my head a few weeks ago, was shooting w my kid the day before a match to check some speeds snd noticed our shot string increased velocity from shot 1 to shot 10 or so. It was 80 degrees outside.
I just want to be able to be able to forcast my elevation on a cold bore shot vs once I got the barrel hot. I’m considering using my barrel temperate in my velocity calculations on StrelokPro instead of just using air temperature in enviromentals.
If it’s 80 degrees outside and my cold bore shoots 2800 fps, I would like to know what’s going to happen to my velocity when that barrel starts cooking to 130 degrees. I’m thinking to leave the 80 degrees in the environment calculator for air density, however, I might try increasing muzzle velocity inputs as my barrel starts to resemble a furnace.
An IR laser thermometer might really help understand muzzle velocity better so you can get better forecasting and powder sensitivity.
I have often wondered about this as well. I live and shoot in Arizona, and heat can really become a factor. Especially when shooting 5 shot groups in large capacity Magnums.
I think the faster the powder, the more this would be a concern. Say with Varget as opposed to Retumbo. I have chronographed loads out of my .338-378 Weatherby, which holds a bit more powder than the .338 Lapua, and I have not seen much, if any, increase in velocity.
But admittedly I haven't shot that rifle in extreme heat. But even when it's in the 60's, that thin Weatherby barrel gets plenty hot. So much so I usually limit my shooting with it to 3-shot groups.
I think the Mile to Matches podcast covered this around ep16… good stuff
Beware, on a polished barrel, an IR temp reading can vary quite a bit depending on lighting conditions.
Here is 20-30 shot string in 5-10 minutes. I ran my scope from 200-1000 back to 100 to check zero with a HOT barrel. Not bad for an off the shelf Ruger RPR with a can. 5 shots.
This picture is rather ancient, (1999). But it shows 6 shots out of my .338-378 shot in under 5 minutes. Not much spread as it heated up. The lower group was shot last. Not too bad considering 588 grains of powder was consumed.
I couldn't keep my hand on the barrel for very long immediately afterward. And in today's world, H-1000 isn't all that slow.
I couldn't keep my hand on the barrel for very long immediately afterward. And in today's world, H-1000 isn't all that slow.
A scary topic and some heated points of view.
I have been on ranges during truing for transonic ranges: on multiple occasions if the target/range was not established within 8-10rds the gun was put to the side to cool. One of the primary reasons was they could no longer engage the target consistently. 300Norma x 1600m.
My personal experience with a stock TRG-42 -300Wm. Cold bore incredible capability, 4.5,6 rounds great. Thereafter on the 1000yd target the group would start to open and string.
3rd party input: "our standard 6mm starts walking at 30rds or so, your barrel not even an indication until 50plus rounds".
ELR- cartridges have been discontinued/dropped because of their tendency to create (system) velocity migration. In fact many ELR shooters compensate for velocity migration.
Our barrels absolutely will shoot a longer string, lower SD's, smaller group than standard barrels. They are radiators for heat. They are also stiffer per weight than a standard barrel. While the above examples existed during truing we continue shooting double the round count plus with a 33xc. Our Norma... let's multiply those numbers by 3 or 4 before the groups start opening up. Our barrels are designed to cool themselves with every shot. A standard barrel is a tube. It will expand with heat. While or inner bore also wants to expand a cool large OD inhibits this movement.
Interestingly we have been told that shot strings beyond 3 don't matter because "their guys will never fire more than three rounds".
Metals- you can absolutely tell manufacturer A to B to C as you machine the barrels. Chips, noise, speeds and feeds.
We have seen (of all types) barrels fail in 200rds and have the exact same supplier and configuration go along past 800rds- 300gr solid at 3250fps.
Metal temps during shooting- the goal (in our opinion) is to keep the throat below transitional temps. When you borescope a barrel for attributes, good, bad, lands shot out.... it is obvious more than one input is responsible for at least 50% of the failure. Solving a multi attribute failure mode is a hard task as you can correct one failure mode and still continue with catastrophic failure due to the other attributes.
Stress relief and heat treat- done correctly all is good. Done poorly- the best barrel fails.
Cryo- full believer. We have hardened 4" and 6" diameters of D2 and wired wafers off of the round. Non cryoed wafers curled like a potato chip- cryoed - flat. Also- about every oil pump out there has cryoed gears. Automotive is about cheap as you get- if they could skip it they would.
A hornets nest- 416SS. Look up its rating for machinability as compared to other steels...
Heat moves frequency nodes (yes- I am very aware first hand that some groups do not believe harmonics effects accuracy). Strum a guitar string- and heat it. Ring a tuning fork before and after applying heat. Not only to frequency values change- their node positions change. Plus materials will have more than one tuning frequency. Changing temperature will move the different peaks at different rates.
Of course it all comes down to needs. F1 guys throw out barrels at >1/4moa, PRS guys 1/2moa is a bad barrel, a guy happy shooting hogs might not care about a 1.5moa gun.
Not sure if its a challenge - I would absolutely accept a challenge standard barrel vs ours. 1000yds- factory or loaded ammo-- extended string until one barrel plainly looses. Lets put some heat in 300cal or larger. Small cals heat input is very slow...
Heat matters. Harmonics (in our opinion) matters. Otherwise everything would be pencil thin barrels- generally speaking. Though... on the far side, tank barrels, Iowa Class Battleships, Artillery... all have technically pencil thin barrels.
I might be out of line here, but 100 or 200 yard shot strings are not going to prove anything in regards to an increase of 50 fps due to higher barrel temperatures.
Not sure if this response is to me... never said anything about 100-200 shot strings. But I certainly think 20-40shot strings with a caliber over 6mm or sub 3kfps is a fair goal. I also think more than 3rounds or 8 rounds is required. As in holding a group size, group location, low extended SD's... and actually I think if we can solve 100+shot strings other issues will be solved also. I would not consider a TRG-42, agreed older (2002), a junk gun, but on its best day the stock barrel does not hold a candle to our tech as the round count goes up- as in 8,9 ,10... To your point- and I am not taking away from it- a huge percentage of shooters are more than happy with 3-5shots. Not an issue with that stance. Others... if my life depends on it I will want a system that can deliver precise rounds for as long as I need it too...
I was referring to the groups at 100 and 200 yards , not shot counts. I was responding to all the pictures of group sizes and I’m not sure what those can teach us about muzzle velocity if they are taken at such short distances.
Thanks Op
To that I am absolutely in agreement. To a certain range velocity is king. Gravity is the over-riding input. To your point creating a "zero" on a system in which the intersecting lines of bore height and line of sight within given distances in my mind can create error- including hiding velocity issues. Do an exercise on a ballistic solver. Plot +/-10yds or meters from a 100yd zero and see the small variation that occurs over blank yards distance. The variation might well be within the standard accuracy of your platform. Now apply a +/-10yd zero to a 100yd (example) sight in and see were the rounds go as the distance increases. While we zero at 200m (down side has started) we also recognize the need to really isolate the platform from the shooter. Solid rifle, solid shooter, good trigger pull- consistency. While everybody might not have $800+ in rifle platform rest components- a shot group of 10 or more should start producing a true group and true sight in value for the optic.
Plus... variation due to a load is one thing. Velocity due to inconsistent ignition is a totally different problem. That failure can show up on that single shot during a hunt.
Tell a 1000yd bencher that ES and SD don't count... all depends on how small the target is as compared to the distance.
