.416 Cold bore interval

[gherardini]

I've had my Model 99 .416 now for about 6 months, put about 70 rounds or so through her and am now looking to rezero her. What I have found over the past time with her on the range is that there is a definitive difference between how she shoots cold vs. how she shoots warmed up.

After 3 - 5 rounds, she will settle down, but she is shooting at least an MOA higher but will continue to do so fairly reliably after that. Great if I want to sit at the range with her all day.

If I place 2 rounds within only a couple minutes of each other, round #2 will be off [high] of the original cold bore round by 4 - 5 inches at 100 yds.

Giving a lot of thought about how I wish to use her, I will likely want to be able to rely on a cold bore shot. That said, how long should I wait between rounds to let the barrel cool down enough that I can get fairly consistent "cold bore" shots out of the barrel?

Thanks all!

[Travelor]

The barrel will have to tell you that. Shoot your first cold bore shot of the day and wait 5 minutes and shoot a second- is this shot with the first? If it is, wait 4 minutes and fire again -is this shot with the first 2? On and on until the POI changes

This should tell you at what point the barrel has cooled to the point of "cold bore zero". But rememebr that barrel heat has a way of being cululative - it keeps a little heat between shots that over a number of shots will cause the barrel to retain more and more heat.

Be sure to have a log book and annotate it with each range session. If not, you will not remember what happened if you are like me.

George

[Bender]

Make sure you are using very precisely loaded ammunition for this, otherwise there are too any variables for this test.

[Espada]

[i]"If I place 2 rounds within only a couple minutes of each other, round #2 will be off [high] of the original cold bore round by 4 - 5 inches at 100 yds."[/i]
4 or 5 inches at 100 yards ! Very unusual for a free-floating barrel. Often, barrel warming/expansion affects point of impact because some part of the stock or other fixed accoutrement bears on the barrel, and the expansion increases the bearing pressure, throwing the shot away from the direction of the barrel/stock contact.

The 99 barrel is free-floating for most of its muzzle-end length... you're not shooting with a Bushnell scope, are you ??

[gherardini]

Thanks all.

I *wish* I had only to wait 5 minutes or less between rounds. Right now I'm waiting 15 minutes and it'll still put subsequent rounds high. Maybe I shouldn't clean it as frequently? Right now I'm cleaning after each range day, anywhere between 3 - 10 rounds. Come out the next day, shoot one very close to center [3/4" right, 1/4 high], subsequent rounds are 4" high.

I am using all Barrett ammo and typically from the same batch.

Using the Leupold scope with a BORS, not that the BORS is much use at zeroing range of 100 yds.

I am really feel frustrated by this with the determination to be able to count on the first round out of the chamber. Subsequent rounds always go high, never had that not happen. If I wanted to have range days, after 3 rounds, I'd shoot consistently all day long. But at this point after one round, I'm making adjustments, nuts!

[yamahawr400]

now i cant speak for the 416 but ill speak on part of my 50. i refer back to the bushnell scope issue as prob 1 to check out. if u have another scope then skip to this. does your 416 have a steady rest under the rear of ur gun? ex monopod, solid sand bag rest, or some other solid 3rd point of contact with the ground? u can make due with a camelback water system, clothing, whatever you would use in the field to steady the back of the gun. if you dont have a solid 3rd point of contact as listed above you may have the same prob i had. you wont get a consistent shot placement due to the movement of the rear of the gun. this was the advice i got from kyle when i went to new mexico for long range basics 1. he was right once i got a solid 3rd point of contact my shots increased in accuracy big time. i credit him with a big time help on a very minute prob if u will.

[gherardini]

now *that's* a very interesting solution.... i may have to consider that and see what results occur!

[tbuck]

No doubt the heat can cause some problems but should not with the first 3 to 5 rounds. I have seen more problems with barrel vibration on the big guns than heat. Also on all of my department sniper rifles I always keep the barrel fouled. After a day at the range I clean my rifles then fire one round then run one dry patch. They hit POA every time.