hp nationals

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dan222
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hp nationals

Post by dan222 »

hi folks,
looking at the hp nanionals 8/6-8, question, does that mean we will shoot one gun each day :?: or two guns each day :?: I only have a hunter rifle, and the gun would get very hot shooting two guns. thanks......dan
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dustinflint
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Re: hp nationals

Post by dustinflint »

The nationals matches are two matches per day. A 40-shot standard match in the morning and a 40-shot hunter match in the afternoon for 3 days for a total of 120 shots for standard and 120 shots for hunter.

If you are shooting your hunter rifle in standard and hunter, you'll shoot it twice per day. It can handle it. It's made to be shot...

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Trent
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Re: hp nationals

Post by Trent »

Yeah, it won't get too hot. Nothing to worry about there.

You want a hot gun, go shoot the Midwest regional in St Louis with one gun. Snake runs his matches quick.very little down time.
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Re: hp nationals

Post by Bob Mc Alice »

dan222, I wrote this back in Sept. 2012 about felt barrel heat. We were shooting 60 shot matches then and a few voiced concerns about damaging barrel heat. In the end, yeah it will feel hot but not nearly hot enough to worry about damage. Barrel steel at cherry red is 1800 F, melts at 2200 F.



I wanted to know just how hot the surface of a barrel got after firing 15 shots. I made up a seven foot long thermocouple lead for my digital thermometer. This thermometer gives instant readouts making it ideal for this test. An inch of bare conductor contacted the barrel and was covered by a one inch square of .005 brass sheet, then taped in place to prevent moving. Placement was just ahead of the chamber a few inches. During morning practice I set up my 7-08 heavy gun and fired 15 shots non stop in a steady but not rushed pace. I was busting chickens and pigs while Dave was recording the numbers. The load was a 130 SMK and 37.0 grs. Varget. The ambient start temperature was 62. Shot #1...66... #2...74... #3...79... #4...84... #5...89... #6...94... #7...97... #8...102... #9...106... #10...110... #11...113... #12...116... #13...120... #14...124... #15...127. So, the final temp reading was only 127 after 15 shots.

During the actual match we set up Daves 6.5-47L hunter gun for testing. This time all other testing was under actual match conditions with brief pauses between sets of five. Due to the wind we were using up most of the clock. The load was 33.0 grs. Varget pushing 123 SMK's. Ambient start temp was 87. Shot #10 was 126 and #15 was at 142 degrees.


Scott volunteered his stock Rem. 700 blue 24" 7-08 hunter for the test. His ram load is 40.0grs. Varget pushing a 168 SMK. Ambient start temp was 90. Shot #10 was 142 and #15 was 158.

Lastly I set up my 7-08 hunter gun. Load is 38.0 grs. Varget with a 150 SMK. Ambient start temp was 90. Shot #10 was at 144 and #15 at 155.

The test showed that for every shot the temp increases by about four degrees. Adding five extra shots for a 60 shot match adds about 10-15 degrees to the final barrel temp using Varget.
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Re: hp nationals

Post by Varn »

My goodness Bob! What an informative post! I am thankful that you guys put forth the effort to record the temps after each shot. I'd have never guessed they were only 150 or so. Thank you again for the effort. Mark Varner
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Re: hp nationals

Post by OldRanger »

Excellent info Bob. Do you know how long it takes to get back to starting temp after firing a string? Do you think it gets all the way back down during the time it takes to reset?
I buy all my guns from t-rex. He's a small arms dealer.
Bob Mc Alice
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Re: hp nationals

Post by Bob Mc Alice »

As a matter of fact I do. I left the thermometer attached to my rifle during the reset period. I remember commenting to Dave B. that it took only 12 minutes to return to the 90 degree ambient start temp. It was windy and warm that day, the wind helped pull the heat out a little faster.
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Re: hp nationals

Post by Trent »

And that is why he is called the Guru
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Re: hp nationals

Post by jask »

The worst conditions I ever had for barrel heat was a 40 round match, began at chickens with 5 shots, reset animals, second 5 shots, reset, moved to pigs, 5 shots, reset, 5 more and so forth all the way through rams. I knew my hunter was going to lose all accuracy so I poured 2 bottles of water on a towel to cool the barrel. 2 more bottles of water half way through and the bullets still went right where I called them. You absolutely could not touch that barrel. That is what you get when pistol shooters run a HP match.
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Re: hp nationals

Post by DanDeMan »

External barrel temp is not that important when it comes to land erosion, what really matters when it comes to loss of accuracy, as a function of number or rounds fired through a barrel. Lands are skinny, of little mass, they get the hottest gases in the leade and they therefore get much hotter when rounds are fired than the external surface of the barrel. It is the heat-cycling that cracks the lands and causes bore erosion: hot then cool down quickly...hot then cool down quickly....ad nasium. The heavier the barrel contour, the lower the external temp. That's why the Hunter barrels get hotter, externally.
Last edited by DanDeMan on Fri Mar 06, 2015 6:08 am, edited 2 times in total.
Cheers,

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Re: hp nationals

Post by jask »

Hi Dan, Are you saying that it does not hurt the barrel any more to fire 40 rounds in 30 minutes verses maybe an hour? How fast would you have to fire to shorten the life of a barrel?
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Re: hp nationals

Post by DanDeMan »

jask wrote:Hi Dan, Are you saying that it does not hurt the barrel any more to fire 40 rounds in 30 minutes verses maybe an hour? How fast would you have to fire to shorten the life of a barrel?
No, I'm not saying that. There are, however, several factors that affect land temp in the leade area, where heat cracking occurs. First, chromoly barrels absorb about twice the heat per round as stainless steel barrels; so, the leade area of a chromo barrel will become hotter, quicker, all other variables held constant. Second, it depends how hot the rounds are with respect to heat cracking issues. Low pressure rounds that are typically shot at CPT's don't heat the barrel up as much. Third, is the barrel in the hot summer sun while shooting and is the ambient temp high? That can make quite a bit of difference in how hot the barrel becomes. With a silhouette rifle, most land damage occurs with ram loads. Shooting 5 ram rounds in 2:30 min will get the rifle pretty hot in hot weather, especially after shooting the second and third banks of animals. Putting the rifle in a rack, in the shade, between relays helps. There are also ways to cool barrels down quickly. Starting a relay with a cool barrel is the best way to reduce heat cracking. Finally, the smaller the caliber, typically, the quicker the lands erode. Oh, double and triple base powders erode barrels quicker than single base powders because nitroglycerin/nitrocellulose powders burn hotter than just nitrocellulose powders. So, you see, there are a number of variables to deal with when it comes to getting the barrel really hot.
Last edited by DanDeMan on Sun Mar 08, 2015 8:29 am, edited 1 time in total.
Cheers,

Dan Theodore
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Re: hp nationals

Post by jask »

Hi Dan, Where did you learn all this stuff, triple base powders, etc? I guess I did a dumb thing by using the same load for all animals. I didn't mind the recoil and just wanted to keep it simple. I did use different loads for Carol's 7 TCU but that was because the ram brass had a short life.

BTW, have you ever done any work on vibrations of action components?
Bob Mc Alice
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Re: hp nationals

Post by Bob Mc Alice »

Hey, thanks for the thanks ,Varn. :) This little test put the worriers at ease that weekend. Since then, we are back to the 2x40 match format.

I remember a decade or so ago someone selling a CO2 barrel cooling system. Had a small refillable tank, valve and hoses to swamp the hot bore with cold gas. Have not seen it advertised in a long while.
Last edited by Bob Mc Alice on Tue Mar 10, 2015 6:03 pm, edited 1 time in total.
Varn
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Re: hp nationals

Post by Varn »

Bob,
I believe the barrel cooling system you are referring to was called Winter Breeze. It was made by Norlin Enterprises in Sioux Falls, SD. I remember because I wanted to try one but was worried I'd hurt my barrel. Mark
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