I'm helping a friend with his 257STW. The cold bore shot is as bad as I've ever seen. It's 1.5" higher than the next 4 shots. We have tried different powder, bullet, you name it. Finally just sighted it in on the cold bore and let it go (hunting rifle). I was wondering if cryoing the barrel would help with the problem.
Gunsmithing Wil Cryo help on cold bore shot..
- Thread starter summitsitter
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Re: Wil Cryo help on cold bore shot..
Want a DIY method? place the entire receiver and barrel or just the barrel in you oven. Turn on at 175 degrees. Every 15 minutes, turn it up another 25-50 degrees. Repeat until 450 degrees and let is bake for 30 minutes. Then turn the oven down 25-30 degrees every 15 minutes until back to off and let it remain in the over until back to room temp. The place it in a large cooler with ice packs for at least 4 hours, then add a small block (1/2 pound) of dry ice for 4 hours. Then get some liquid nitrogen and add to the cooler. If you have an insulated container like a Thermos bottle, you can get some at a detmatolagist. Let it stay in the cooler until it gets back to room temp.
It should be stress relieved at that point. Note: I have no hard data to back this method up. Just based on experience with stress relieving of other metal parts and my investigation of the process.
Want a DIY method? place the entire receiver and barrel or just the barrel in you oven. Turn on at 175 degrees. Every 15 minutes, turn it up another 25-50 degrees. Repeat until 450 degrees and let is bake for 30 minutes. Then turn the oven down 25-30 degrees every 15 minutes until back to off and let it remain in the over until back to room temp. The place it in a large cooler with ice packs for at least 4 hours, then add a small block (1/2 pound) of dry ice for 4 hours. Then get some liquid nitrogen and add to the cooler. If you have an insulated container like a Thermos bottle, you can get some at a detmatolagist. Let it stay in the cooler until it gets back to room temp.
It should be stress relieved at that point. Note: I have no hard data to back this method up. Just based on experience with stress relieving of other metal parts and my investigation of the process.
Re: Wil Cryo help on cold bore shot..
Good advice. How much it helps also has a lot to do with how much stress is in the barrel. Are you taking the cold shot right after cleaning or with a dirty barrel?
Good advice. How much it helps also has a lot to do with how much stress is in the barrel. Are you taking the cold shot right after cleaning or with a dirty barrel?
Re: Wil Cryo help on cold bore shot..
Most barrels are stress relieved at the factory there may be some exceptions.A simple way to cryo treat is using a Styrofoam cooler kerosine and dry ice.You may place the cooler in another cooler to slow down evaporation.Just place the barrel in the bottom of cooler completely cover with K1 then add a butt load of dry ice seal the edge of cooler with duck tape and wrap in towels or put in another cooler.You must wait several days until all the dry ice is evaporated,use gloves it will burn you if ice is present.
Please be careful with the above K1 is flammable and dry ice burns.
Most barrels are stress relieved at the factory there may be some exceptions.A simple way to cryo treat is using a Styrofoam cooler kerosine and dry ice.You may place the cooler in another cooler to slow down evaporation.Just place the barrel in the bottom of cooler completely cover with K1 then add a butt load of dry ice seal the edge of cooler with duck tape and wrap in towels or put in another cooler.You must wait several days until all the dry ice is evaporated,use gloves it will burn you if ice is present.
Please be careful with the above K1 is flammable and dry ice burns.
Re: Wil Cryo help on cold bore shot..
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: isaaccarlson</div><div class="ubbcode-body">Good advice. How much it helps also has a lot to do with how much stress is in the barrel. Are you taking the cold shot right after cleaning or with a dirty barrel? </div></div>
dirty
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: isaaccarlson</div><div class="ubbcode-body">Good advice. How much it helps also has a lot to do with how much stress is in the barrel. Are you taking the cold shot right after cleaning or with a dirty barrel? </div></div>
dirty
Re: Wil Cryo help on cold bore shot..
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: P.A.R.</div><div class="ubbcode-body">
Please be careful with the above K1 is flammable and dry ice burns. </div></div>
I am not trying to be an ass, but dry ice does not burn. It is solid CO<span style="font-size: 8pt">2</span>, the carbon is in a +4 oxidation state, and therefore cannot be further oxidized. It will give your skin a cold burn, and it can potentially suffocate you if you have no ventilation, but it will actually make the kerosene less likely to catch on fire due to Le Chatelier's principle, the fact that cooling the kerosene will lower the partial vapor pressure above it, slow down the kinetics of oxidation.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: P.A.R.</div><div class="ubbcode-body">
Please be careful with the above K1 is flammable and dry ice burns. </div></div>
I am not trying to be an ass, but dry ice does not burn. It is solid CO<span style="font-size: 8pt">2</span>, the carbon is in a +4 oxidation state, and therefore cannot be further oxidized. It will give your skin a cold burn, and it can potentially suffocate you if you have no ventilation, but it will actually make the kerosene less likely to catch on fire due to Le Chatelier's principle, the fact that cooling the kerosene will lower the partial vapor pressure above it, slow down the kinetics of oxidation.
Re: Wil Cryo help on cold bore shot..
or you could just have your bullets coated with boron nitite....
or you could just have your bullets coated with boron nitite....
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