Post by: Gobble Gobble on January 06, 2011, 09:53:16 PM
So, my question for all you is… Just how much is the pressure increased (I’m sure it depends on the powder used) having to seat a lead free bullet deeper verses a lead core bullet? Is there any real increase in barrel heat, wear and the possibility of barrel damage due to the increased pressure? How about loading to 10% less max charge? My wife prefers to load to max charge I like to go a grain or two less depending on what I’m loading for. Any info would be appreciated.
Post by: bobcat on January 06, 2011, 10:12:35 PM
Also, you won't necessarily need to seat the bullet deeper in the case. If you're not limited by the length of the magazine in the rifle, then you can just load them to the same depth as before, the overall length will just be slightly longer.
Another thing, with the pure copper bullets you can afford to go lighter than you would with a standard jacketed lead bullet and still get the same, or better, performance. With the 30-06, I think a 150 grain Barnes would be great for anything. The extra velocity will help in expanasion, especially at longer ranges when it will have slowed down some.
You should still start your load development well below the max charge listed in your book and work your way up. But your pressure with the max load you end up with shouldn't be any higher than what you would have with a lead bullet.
Post by: bobcat on January 06, 2011, 10:20:47 PM
Quote
Comparing Bullet Length
How important is bullet length? Longer bullets have a higher ballistic coefficient (BC), which means more retained energy and flatter trajectories for long-range shooting. They also align better within the bore, promoting greater accuracy. These are some advantages long bullets offer.
On the other hand, long bullets project farther into the cartridge case, limiting powder capacity. Extremely long bullets may compress powder charges, particularly in short-action cartridges loaded to standard overall length. Long bullets are more likely to promote fouling, and require a relatively fast rifling twist to properly stabilize en route to the target.
Some have mistakenly thought Barnes’ all-copper Triple-Shock X Bullets were (a) longer than competing premium bullets, and (b) caused pressure and fouling problems because of the perceived greater surface area contacting the bore.
Here are the facts:
When a 160-grain 7mm Barnes Triple-Shock X Bullet was measured against Speer Spitzer SP, Nosler Partition, Hornady SST and Nosler AccuBond bullets of the same weight and caliber*, the Triple-Shock was longer than the Speer Spitzer and Nosler Partition, but shorter than both the Hornady SST and Nosler AccuBond bullets.
(* The Hornady SST weighed 162 grains.)
When 180-grain .30-caliber projectiles were compared to a Barnes Triple-Shock X Bullet of the same weight and diameter, the Triple-Shock bullet was longer than Sierra Pro-Hunter, Combined Technologies CT Fail Safe and Nosler Ballistic Tip bullets, but shorter than the AccuBond and considerably shorter than the Swift Scirocco.
Longer than some, shorter than others, Triple-Shock bullets are of approximately average overall length.
There’s more! “Bourrelet” describes the length of the bullet that actually comes in contact with the rifling. Multiplied by bullet circumference, it determines the surface area engraved by the lands and grooves as the bullet passes through the bore.
Barnes Triple-Shock X Bullets have an average overall length, but less surface area contacting the bore. How is this possible?
Multiple grooves machined into the shank of each Triple-Shock X Bullet reduce the bullet’s surface area that contacts the bore, while bourrelet length remains unchanged. The result? Triple-Shock X Bullets create less fouling and pressure buildup than almost all competing bullets. Their unique, one-piece design and generous bourrelet produce unsurpassed stability and exceptional accuracy. With no lead core to fragment or shear away, Triple-Shock X-Bullets retain virtually 100 percent of their original weight for deep, sure penetration.
Post by: bobcat on January 06, 2011, 10:29:39 PM
http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/3216390/Good_30_06_Loads#Post3216390 (http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/3216390/Good_30_06_Loads#Post3216390)
Post by: Bob33 on January 06, 2011, 10:33:54 PM
(I don't know how much of a pressure difference there is due to seating the bullet deeper per se, but there is definitely a difference in pressure depending on how far the bullet has to jump to engage the rifling):
To illustrate the effects of variations in bullet travel before the bullet enters the rifling, we'll compare a standard load with adjustments made only in the bullet's seating depth.
In a "normal" load with the bullet seated to allow about one 32nd of an inch gap (A) between the bullet and the initial contact with the rifling, pressure builds very smoothly and steadily even as the bullet takes the rifling. Pressure remains safe throughout the powder burning period (B), and the velocity obtained - 3500 fps - is "normal" for this load in this rifle.
Seating the bullet deeper to allow more travel before it takes the rifling, as in these next two illustrations, permits the bullet to get a good running start (C). Powder gases quickly have more room in which to expand without resistance, and their pressure thus never reaches the "normal" level. Nor does the velocity; with the same powder charge it only comes to 3400 fps (D).
When the bullet is seated to touch the rifling, as in the accompanying illustrations, it does not move when the pressure is low (E); and not having a good run at the rifling as did the other bullets, it takes greatly increased pressure to force it into the rifling. As the rapidly expanding gases now find less room than they should have at this time in their burning, the pressure rise under these conditions is both rapid and excessive (F). Velocity is high at 3650 fps - but at the expense of rather dangerous pressure. Many rifles deliver their best groups when bullets are seated just touching the rifling. Seating bullets thus can be done quite safely if the reloader will reduce his charge by a few grains. The lighter load will still produce the "normal" velocity without excessive pressure.
Post by: high country on January 06, 2011, 11:07:06 PM
Post by: Gobble Gobble on January 07, 2011, 08:15:21 AM
Post by: mazama on January 07, 2011, 08:38:59 PM
Post by: C-Money on January 07, 2011, 08:52:56 PM
Post by: Gobble Gobble on January 07, 2011, 09:10:53 PM
Post by: bobcat on January 07, 2011, 09:21:15 PM
Post by: bobcat on January 08, 2011, 08:14:04 PM
http://www.24hourcampfire.com/newsletters/May_2009.html (http://www.24hourcampfire.com/newsletters/May_2009.html)
Post by: Crisptrigr on January 09, 2011, 02:45:38 PM
Much of the information you shared with us in your original post regarding what your wife's brother told your wife is incorrect.
Perhaps he mis-understood the article or the info. in the article was inaccurate.
Post by: timberghost72 on January 09, 2011, 03:34:51 PM
Powder wise, look at IMR 4350.:yeah:
I used this powder at 54 grains with 165 gr Barnes TSX and had excellent groupings.
Post by: MDGrand on January 10, 2011, 07:55:13 AM
Anybody here that can reply with a few links before I start a search over the internet?
Post by: whacker1 on January 10, 2011, 11:18:49 AM
Currently my best is the 168 Berger VLD, which is going the opposite direction for retention of mass. But it flys good. and was plenty fatal at 40 yards this year.
Post by: timberghost72 on January 10, 2011, 01:18:09 PM
Just started reloading myself and had a question about where on the internet I can find the best Barnes recipe for 300 RUM, including max COAL specs, min/max grains, etc?
Anybody here that can reply with a few links before I start a search over the internet?
The Barnes website has load data for their bullets
http://www.barnesbullets.com/ (http://www.barnesbullets.com/)
Post by: Curly on January 10, 2011, 01:29:00 PM
Just started reloading myself and had a question about where on the internet I can find the best Barnes recipe for 300 RUM, including max COAL specs, min/max grains, etc?
Anybody here that can reply with a few links before I start a search over the internet?
As far as COAL goes, just determine what length puts your bullet at 0.050" from the lands and start there.