I finally made it to the range today for the first time since May. I was shooting groups at 100 since I wanted to try out my new can. The two groups I fired prior to mounting the can where both high and right by about 1 MOA. I just removed a brake last week so I could screw a can on. Also the last time I shot it was in the 60s or 70s with the temp today around 90. Im using 41.8 of IMR 4064 with 175 SMK. Im wondering if removing the brake could cause the shift or if it is the temp difference? Ive heard 4064 is pretty temp stable. Also my house is kept at about 75 degrees and I had the air on on the way to range. Im leaning toward temp difference but wanted to see what the more experience members had to say. Ive only been reloading since December. Also there were no pressure signs.
Kinda Newb ? about poi shift
- Thread starter rdgshooteer
- Start date
Suppressors cause poi shifts, so can large temp swings with certain powders. Could be a combination of both.
My guess is most of your POI shift is due to differing barrel harmonics generated with and without the extra/different weight of the suppressor/brake mounted on the end of the barrel.
Like stated above. Both the can and temps could cause Point Of Impact shifts. Crap... almost everything can cause POI shifts. But try firing your ammo that you have stored in a cooler, wrapped in a towel on the way to the range, and also when you fire. Our firing point is covered with a shed roof. But temps still get quiet warm this time of year.
Because of the temps caused by the burning gas when you fire the round, wait a couple of minutes with the bolt open to let some of the heat escape. Still leave the bolt open until you are ready to fire. Just until you get the feeling of the wind will help keep it a little cooler. Chamber and barrel temps can get very hot if you don't let them cool some between shots.
Get a little porch thermometer and take with you. That'll help with your records... Records. You DO take a notebook to the range with you, don't you? Or you can get one of the little indoor outdoor electric thermometers and peal away the encapsulate from the temperature sensor and use masking tape to hold the sensor on the barrel right in front of the receiver. That will give you a pretty accurate reading on what your barrel temps are.
I hope this helps.
Victor
Because of the temps caused by the burning gas when you fire the round, wait a couple of minutes with the bolt open to let some of the heat escape. Still leave the bolt open until you are ready to fire. Just until you get the feeling of the wind will help keep it a little cooler. Chamber and barrel temps can get very hot if you don't let them cool some between shots.
Get a little porch thermometer and take with you. That'll help with your records... Records. You DO take a notebook to the range with you, don't you? Or you can get one of the little indoor outdoor electric thermometers and peal away the encapsulate from the temperature sensor and use masking tape to hold the sensor on the barrel right in front of the receiver. That will give you a pretty accurate reading on what your barrel temps are.
I hope this helps.
Victor
Thank you guys for the help. I didn't even think about the harmonics with taking off the brake. Yes I do bring a note book with me. I will most certainly try the cooler and towel trick and pick up a porch thermometer. Our firing point has the same type aluminum shed roofing on it.
The POI shift for the can were as expected low and left. It was the POI shift without anything on the barrel that had me confused since I had heard that 4064 was fairly temp stable.
The POI shift for the can were as expected low and left. It was the POI shift without anything on the barrel that had me confused since I had heard that 4064 was fairly temp stable.
