20” 243 barrel. Will unburned powder affect accuracy?

[RidgeTine]

I've had this Remington 700 youth in 243 with a 20 in barrel that hasn't shot that well until I put 38 grains of Hodgon 4350 behind a 100 grain Nosler ballistic tip. Anymore powder than that and doesn't do well. Question I have; is there unburned powder affecting the accuracy? 38 grains on left and 41 grains of powder to right in photo. Another note I sanded out the factory stock forearm to free float the barrel. It's not bedded and this is the first outing I've had with a free float barrel. Mind you this is the first outing I've had where there's actually been a pattern. I don't think this barrel liked all the pressure the stock had on it.

 

[RidgeTine]

i guess I wasn't sure how to ask the question. What's it called when there's still powder burning after the bullet leaves the barrel?

 

[YZ-80]

Maybe you're thinking of the term "Overbore" loosely defined as a high amount of powder to burn in relation to cross sectional bore area. I'm just gonna guess that you have a 1:10 twist barrel. I think H4350 might be too slow a burning powder with the short tube and you might do better with an 85 grain pill and/or faster burning powder?

 

[Dmagna]

Try varget

 

[dreamhunt]

When loading light loads in pistol calibers I have found unburned powder often. Increasing the amount of powder reduced the amount of unburned powder and going above mid-range gave me a clean burn. I would expect the same would happen with rifle loads. Years ago I noticed the same thing with shotgun loads. You will find as you work up a load many times there will be points where the groups tighten up then spread out as you increase the powder than tighten up again. When you get close to or at max loads normally your groups will just keep spreading because of spikes in the load.

 

[Toddxusmc]

The unburnt powder will not in itself destroy accuracy. Your 38 grain load is the better load for you, the bullet is leaving the muzzle closer to the same time and place in the vibrational harmonics, you have found an accuracy node in that particular rifle, a different powder with the same bullet may give you even better accuracy but it will take time to test. One thing you could try to more efficiently burn powder is try a different primer, possibly a magnum primer for better ignition. You're other option would be to go to a faster burning powder, the burn rate of H4350 is on the faster side for .243(imo) and isnt a bad choice for your rifle, when I loaded.243 in my Tikka ("22) I had great results with H4831, and going even as slow as IMR7828 with 100-105gr bullets.
With any load accuracy is paramount as well as consistency and uniformity of components, especially for longer ranges.

 

[Adam Moore]

My son and niece are running RL 15 with 80 gr tipped triple shock at roughly 3200 FPS with .5 MOA and smashing deer out of 20" 243 youth model 700's.

 

[Aoudad shooter1975]

Short answer is no...

 

[RidgeTine]

Got it. So just keep tweaking loads until I blow out primers or make clover leafs.

 

[bigedp51]

I've had this Remington 700 youth in 243 with a 20 in barrel that hasn't shot that well until I put 38 grains of Hodgon 4350 behind a 100 grain Nosler ballistic tip. Anymore powder than that and doesn't do well. Question I have; is there unburned powder affecting the accuracy? 38 grains on left and 41 grains of powder to right in photo. Another note I sanded out the factory stock forearm to free float the barrel. It's not bedded and this is the first outing I've had with a free float barrel. Mind you this is the first outing I've had where there's actually been a pattern. I don't think this barrel liked all the pressure the stock had on it.

On Remington 700 many of these rifles are not free floated and have a raised bedding area at the fore end tip. This gives the barrel 3 to 9 pounds of up pressure to control barrel vibrations and help accuracy.

The reason I bring this up is I did the same thing to my Remington 700 .243 in the mid 1970s and removing the up pressure and made the rifle shoot much bigger groups. Meaning Remington put the raised bedding point at the fore end tip for a good reason.

There are two ways to tune a rifle.
The military tunes the rifle to the issued military ammunition. And Remington had the bedding point at the fore end tip because it made the rifle shoot better.
On a rifle with a free floating barrel you tune the ammunition to give the best accuracy.

Example, the military British No.4 Enfield was to have 2 to 7 pounds of up pressure at the fore end tip. And the amount of the rifles up pressure was regulated to give the best accuracy.

How Does Barrel Bedding Affect Accuracy?
By Jon R. Sundra
Not all barrel bedding is equal. Bedding dynamics can increase or decrease a rifle's accuracy. What are some things to know about bedding dynamics and accuracy?
https://gundigest.com/rifles/barrel-bedding-affect-accuracy

Below I had a Winchester Model 70 .270 with BOSS, and after two adjustment the rifle was shooting groups of 3/4 of an inch or less. And this was with mid range loads I made up to sight the rifle in at 100 yards.

What is the BOSS?
Browning's Ballistic Optimizing Shooting System (BOSS) is a patented breakthrough in rifle accuracy. When any rifle is fired, the barrel goes through a series of vibrations as the bullet leaves the muzzle. The variations of these vibrations greatly affect the accuracy of the rifle. Controlling these vibrations will greatly control the accuracy of the rifle. Browning's BOSS allows you to control the vibrations of your barrel so you can shoot groups you didn't think possible.

How the BOSS works.
The BOSS simply tunes the vibrations of your barrel. This allows the bullet to leave the barrel the split second it is stationary. Your BOSS manual has a list of settings for each caliber and bullet weight. Adjusting your BOSS to these "Sweet Spot" settings allows you to find the instant your barrel is stationary. The result is accuracy never achieved before by an out-of-the-box rifle.