I have a 300 Rum Sendero. How far from the lands do you guys seat your bullets? I've had some luck with .010, and sammi length and 3.8 same as wyatts box. Not great though. Please help. Powder used was retumbo.
AR-10T in .308 & .243 both 24"
700 LA 7 WSM 30" 5R
AR-15 Rock River lower, WOA 26" varmint upper
Savage/ Broughton 23" .308
I am going through exactly the same process at present but in a .300 Win Mag sendero SFII.
I am still using H1000 as stocks of Retumbo in the U.K have run out for present.
To date I have had no luck with loads seated to regular factory lengths so on my next batch I intend to move the bullet (200 grain Accubond) to .010" back from the lands and work backwards in .005" increments from there until acceptable accuracy is attained.
Rounds seated at .125" back showed no inclination whatsoever to group save in the case of one factory load, this being the GECO 180 soft point, a run of the mill bullet, not bonded or anything special, but nevertheless one which puts 3 shots well inside 5/8" at 100 yards.
Had this been a high BC bullet I would be tempted to stick with it for all hunting, hence my desire to obtain good accuracy with the Accubonds. I know they are a good accurate bullet so I just need some spare time to try out different load configurations.
You should be able to obtain good accuracy with the load set up you have there, again sounds like you have not yet found the ideal seating depth.
Have you carried out any mods to the Sendero such as lighten trigger pull or skim bedding?
Have you tried any faster burning powders in your 300 Win Mag and 200 gr Accubond? I am doing some load testing with a couple of 300 win mags with this bullet. I am finding that I can get just as high of velocity with burning rates like IMR 7828 and RL22 but with 6 or 7 grains less powder than H1000 and minimal load compression at magazine length. I would think that you would have to cram a lot of Retumbo in the case to get max velocity.
Just some food for thought.
The critters have to win every time, I only have to win once.
The accubond is a fairly thick jacketed bullet so it may like a little bit of a jump to the lands, something you might wanna try. In the opposite direction you might just touch the bullet to the lands or even in .005 in the lands. If you do this back off your load a little bit and work back into it, gotta watch those pressures.
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[ QUOTE ] In the opposite direction you might just touch the bullet to the lands or even in .005 in the lands. If you do this back off your load a little bit and work back into it, gotta watch those pressures.
[/ QUOTE ]
IMAO - great for ivory tower BR loads, bad for hunting. Anything tighter than .030 off the lands with custom a chamber and you'll have some cartridges jam into the lands and stay there. Eject the cartridge and powder pollutes the magazine. Now try to chamber another round and a few loose grains you missed while field cleaning the dumped powder prevents bolt closure. I did this with two of my custom guns (which are 20 times harder to find the lands than a sloppy factory chamber). Luckily I was only varmint hunting in the first case and deer hunting with a backup in the second case. Note I had tested (chambered/ejected) each round before the hunt. I suppose with run-out changing, temp changes, one managed to jam. (I was .010 off the lands).
When I read folks talking .015 or tighter off the lands, I suspect they don't have reliable loads OR are not really that tight OR have a sloppy factory chamber OR they are real good and know their stuff. I know some guys have the skills to measure this tight and produce robust loads, but after a year of trying I gave up. Lucky for me my Kirby built guns seem to shoot great even backed .050 off the lands.