SAAMI chamber? My experience with SAAMI chambers in 6.5 CM with the .199" freebore is that the closest I could get to the lands was about .070" off with 140 HT's while staying inside mag length of my MDT mags with binder plate (they publish max of 2.87.
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Likewise, I've experimented with my .308 where I found a good seating depth the produced really well for a long time not changing it for ~2,000 rounds fired. Of course, the throat eroded and the jump over that time increased substantially. I did this test after reading about several top notch shooters telling how they never change their seating depth for the life of their barrel (smaller calibers with barrel life less than 2,000 rounds). This was what really convinced me that seating depth was way more important than jump and that jump was really not anything one should focus on with developing a load. . . except to know where the lands is on their particular gun to decide a starting point. That why I often cringe when I see people asking about someone's jump instead of asking about seating depth.SAAMI chamber? My experience with SAAMI chambers in 6.5 CM with the .199" freebore is that the closest I could get to the lands was about .070" off with 140 HT's while staying inside mag length of my MDT mags with binder plate (they publish max of 2.87.
Another .070" would put you at about .140 off of the lands....to me, that's a bit much BUT the 140 HT's are reputed to be very jump tolerant and I did see some time ago Satterlee was experimenting with jump out to .250 and in the article linked below, he said:
"One of those is Scott Satterlee, who has placed in the top 10 in both the PRS and NRL in the overall national standings in recent years and is clearly one of the best shooters in the country. Over the past two years, Scott has experimented with freebore and bullet jumps all the way out to 0.250 inches! He is now on his 5th barrel since he’s been experimenting with longer bullet jumps and said, “This isn’t something that I’m still wondering if it’s true or not. After 5 barrels, I know it’s real. There is a real improvement and benefit here.”Bullet Jump Research: Executive Summary & Load Development Tips
This is the last post in a series of articles focused on bullet jump research that has been conduct...In the same article, Wade Stuteville said:
"He discovered on his 6×47 rifles he could start off jumping the 105 Hybrid’s around 0.080” and never have to change the seating depth over the entire life of the barrel and it’d perform great the whole time. Wade explained, “Over the life of the barrel, my jump might change from 0.080” to 0.130” or something, but it never really comes out of tune. And I’ve had a lot of cartridges that have been that way in the past.”Give the article a read....I'm no expert or hot shot shooter....so read it and see if it informs your thoughts at all.
For me...I just recently had a 6.5 CM barrel spun with .150" freebore to let me get closer to the lands....IF that's a place I want to be. Easy to move back more....tough to get close if it exceeds mag length
SAAMI chamber? My experience with SAAMI chambers in 6.5 CM with the .199" freebore is that the closest I could get to the lands was about .070" off with 140 HT's while staying inside mag length of my MDT mags with binder plate (they publish max of 2.87.
Another .070" would put you at about .140 off of the lands....to me, that's a bit much BUT the 140 HT's are reputed to be very jump tolerant and I did see some time ago Satterlee was experimenting with jump out to .250 and in the article linked below, he said:
"One of those is Scott Satterlee, who has placed in the top 10 in both the PRS and NRL in the overall national standings in recent years and is clearly one of the best shooters in the country. Over the past two years, Scott has experimented with freebore and bullet jumps all the way out to 0.250 inches! He is now on his 5th barrel since he’s been experimenting with longer bullet jumps and said, “This isn’t something that I’m still wondering if it’s true or not. After 5 barrels, I know it’s real. There is a real improvement and benefit here.”Bullet Jump Research: Executive Summary & Load Development Tips
This is the last post in a series of articles focused on bullet jump research that has been conduct...In the same article, Wade Stuteville said:
"He discovered on his 6×47 rifles he could start off jumping the 105 Hybrid’s around 0.080” and never have to change the seating depth over the entire life of the barrel and it’d perform great the whole time. Wade explained, “Over the life of the barrel, my jump might change from 0.080” to 0.130” or something, but it never really comes out of tune. And I’ve had a lot of cartridges that have been that way in the past.”Give the article a read....I'm no expert or hot shot shooter....so read it and see if it informs your thoughts at all.
For me...I just recently had a 6.5 CM barrel spun with .150" freebore to let me get closer to the lands....IF that's a place I want to be. Easy to move back more....tough to get close if it exceeds mag length
