[jburke]

Have a load figured out for the .243. Rifle is a Savage model 11. Load is 39.4 gr IMR 4064 with a 100 gr BTSP Hornady. Shot a 5/8" group at 125 yds with the first 4 rounds. The group opened up as the barrel heated (10 rounds) to a 1.5" group. What's the physics behind this?

I'm looking for recommendations on loads for a 75 gr hornady hollow point. The same IMR 4064 is shooting about a 2 to 3" group. Is it the nature of a hollow point to be less accurate? The barrel was already pretty warm when i had shot the hollow points.

 

[kdub]

A hot barrel does not equate to great accuracy. Suggest you let the barrel cool between shots/strings. If you can't comfortably hold your hand on it, its too hot.

Every rifle is an entity unto itself. My .243 will shoot load combinations yours probably would gag on. Only way you will find out what fodder your rifle likes to digest best is to try different load combinations, while allowing the barrel to remain relatively cool - not hot.

 

[jburke]

A hot barrel does not equate to great accuracy. Suggest you let the barrel cool between shots/strings. If you can't comfortably hold your hand on it, its too hot.

I'll give the hollow points the benefit of a cool barrel next time at the range. Was waiting about 5 minutes between strings of 8 to 12. Even after 5 minutes, the barrel was still pretty warm. Temps in the 80's. Come on cool weather.

 

[spitfire_er]

Hot barrel= More pressure= Change in point of impact!

 

[oneoldsap]

If you are trying to test loads in a hot barrel you are just making noise and spinning your wheels !

 

[jburke]

If you are trying to test loads in a hot barrel you are just making noise and spinning your wheels !

Agreed. And wasting bullets. Try the hollow points on a cold barrel next time out.

 

[ranger335v]

Most highly accurate bullets are hollow points.

 

[Arky]

my 243 loves the 75 gr Hornady HP and Varget. I think i stoped at 1gr under max per the Lyman manual with a .45 group at 100 yd. I do not over heat the barrel though. I usually shoot two or more guns as i do not have patience to just sit there.

 

[jburke]

my 243 loves the 75 gr Hornady HP and Varget. I think i stoped at 1gr under max per the Lyman manual with a .45 group at 100 yd. I do not over heat the barrel though. I usually shoot two or more guns as i do not have patience to just sit there.

I'll need to play with loads a little bit more on the 75 gr. Currently, i'm loading at 39.4 gr IMR 4064. That's 2.5 gr under the max per the hornady book. Should be about 3200 fps.

Wasn't saying that i overheat the barrel. It's pretty warm to the touch, but not hot enough to hurt your hand. Just observed that groups open up somewhat when the barrel is warmer.

I'm still learning, so be patient with me.

 

[jburke]

Most highly accurate bullets are hollow points.

That surprises me...not disputing. Seems like keeping a uniform density of the bullet with regards to its longitudinal axis would be more difficult with a hollow point rather than solid.

 

[Arky]

Jburke,
You must be an engineer. Most of us will not have a clue what your reply actually meant, but i get the general idea. I would think there is a lot of centrifical force due to the tremendous RPM's and the center would not have that much to do with it. I do not shoot match and know little about it. I was looking for a varmit load and tried what Gander had on the shelf. I was lucky it shoots so well in my Tikka. As i said, i am not a match bullet expert but i think most of the match grade bullets are HP as in sierra match king. I do not know the reason.

 

[jburke]

Jburke,
You must be an engineer. Most of us will not have a clue what your reply actually meant, but i get the general idea. I would think there is a lot of centrifical force due to the tremendous RPM's and the center would not have that much to do with it. I do not shoot match and know little about it. I was looking for a varmit load and tried what Gander had on the shelf. I was lucky it shoots so well in my Tikka. As i said, i am not a match bullet expert but i think most of the match grade bullets are HP as in sierra match king. I do not know the reason.

Not an engineer by trade, but did attend engineering school at Purdue for 5 years.

I'll keep tinkering with the round and see what i can come up with.

 

[MZ5]

...Shot a 5/8" group at 125 yds with the first 4 rounds. The group opened up as the barrel heated (10 rounds) to a 1.5" group. What's the physics behind this?

Barrel not (adequately) stress-relieved after the rifling process?

 

[TMan]

What's the physics behind this?.

If you've ever poured a cup of instant coffee, and stirred it up, you've probably noticed that the cup sounds different as it heats up. As you add temperature, you increase the vibrational frequency of the cup. Same with your barrel.

I have a M700 Mtn Rifle in 7-08. It's a tack driver for about three rounds, and I can always count on three shots under an inch, with a couple minutes between shots. 5 shots fast and I'm usually at 1.75-2.0". If the range is slow, and there's lots of open benches, it will put 10 shots in an inch, if I shoot one every 5 minutes or so. I shoot one, move to the other bench, or shoot a few offhand with my .22. shoot another one, and so on.

 

[David Milisock]

Hornady 75 grain hollow points

Have a load figured out for the .243. Rifle is a Savage model 11. Load is 39.4 gr IMR 4064 with a 100 gr BTSP Hornady. Shot a 5/8" group at 125 yds with the first 4 rounds. The group opened up as the barrel heated (10 rounds) to a 1.5" group. What's the physics behind this?

I'm looking for recommendations on loads for a 75 gr hornady hollow point. The same IMR 4064 is shooting about a 2 to 3" group. Is it the nature of a hollow point to be less accurate? The barrel was already pretty warm when i had shot the hollow points.

My 6mm Remington shoots this bullet to groups of 1 1/8" at 300 yards with a hyper velocity load I use for chucks.

 

[JJones458]

Hi,
My pet 243 varmint load is the Sierra 80gr Blitz bullet with 38grs IMR4064 and a Federal BR primer at 2.720 oal for my Weatherby Vanguard and it gives me 3100 fps and sub moa accuracy. I also shoot in hot weather in the summer (Middle GA) and rotate rifles and have also used a Ice pack wrapped in a towel to initially cool the barrels, not until they are cold, but to get them started cooling down. With the added moisture you have to give them a good wipe down afterward, but I have had no corrosion problems to date.
Regards, Trapper

 

[Judge]

Hello I use 2 differant loads in my .243 the first load is a 75gr VMAX with 46grs of 2209 powder. I can shoot 4 shoots in a 1inch group at 200yds and with the second load i use 95grs SST's with 43grs of 2209 powder and they shoot really accurate as well. So have fun findng the right load for your gun.Cheers Rick.

 

[hailstone]

If memory serves the reason HP bullets are more accurate is the center of gravity is moved towards the rear of the bullet. This helps in its flight orientation to reduce drag (air friction).