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Posted: 8/10/2012 4:52:11 PM EDT
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At what distance is recommended for stabilizationof bullets
Shooting Ar15 1:9 twist. 75 gr hpbt So I loaded up some 75's I traded a guy for ( 100 40 gr sierra blitz for 140 75's) Loaded up some with tac and went out back set up target at only 70 yards just to see if they key hole. And they didn't should I assume my Ar can stabilize 75's headed to range tomarrow to test them further just curious what the pros think thanks in advance! |
| Not a "pro" but do a lot of reloading for the family's ARs with 3 different twists; 1 - 7, 1 - 8, and 1-9. Only time I've seen a 75 grain bullet keyhole was out of a friend's single shot with a 1 -12 twist. What you may find tomorrow is that your gun doesn't shoot them well. My son's 1 -9 will shoot 75 grain bullets, but shoots lighter bullets much more accurately. Let us know how it turns out for you. Good luck. |
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Quoted:
At what distance is recommended for stabilizationof bullets Shooting Ar15 1:9 twist. 75 gr hpbt So I loaded up some 75's I traded a guy for ( 100 40 gr sierra blitz for 140 75's) Loaded up some with tac and went out back set up target at only 70 yards just to see if they key hole. And they didn't should I assume my Ar can stabilize 75's headed to range tomarrow to test them further just curious what the pros think thanks in advance! Only way to know for sure is to shoot them out of your rifle. It is not so much the weight but the length of the bullet. 75g HPBT are not that long compared to other bullets in similar weights. You will probably be fine. For reference I have a 1:9 rifle that loves 75g bullets (75 A-Max - bolt gun) but does not really like the 75g HPBT bullets for some reason. |
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Quoted:
Not a "pro" but do a lot of reloading for the family's ARs with 3 different twists; 1 - 7, 1 - 8, and 1-9. Only time I've seen a 75 grain bullet keyhole was out of a friend's single shot with a 1 -12 twist. What you may find tomorrow is that your gun doesn't shoot them well. My son's 1 -9 will shoot 75 grain bullets, but shoots lighter bullets much more accurately. Let us know how it turns out for you. Good luck. Thanks! I'm New on the scene of reliading! Not new to AR'S I find myself allways aiming for accuracy not just sending rounds down range. Kinda ocd thing . My time in usmc I never really debated bullet weights just shot placment. So pulled out some of my super precision bullets or so I call them. This right now is geared twits upcoming hunting season. (Blackrail) here are my on hand choice. 53 gr tsx (not heavy enough in my opinion) 69 gr hpbt nosler custom comp wich I can shoot sub 1" @ 100 yards , hornady 75 gr hpbt as well as 60 gr sp, the 69 flavor shoots best but not sure bout the hpbt for hunting purposes. Custom comp shoots allot better than smk at least the one box anyway . Was really hoping those 75's were stabilizing but was holding out for range time. I only shot one 5 shot group just too see. Going on Monday to nosler hq have a friend works their get some 60 gr partition. Just wish they made 70 gr in that. Oh if anyone's interested nosler coming out new reloading data book late this year. |
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Check over at the AR-15 / Ammunition forum FAQ section: "What twist..." for a good discussion on the subject.
http://www.ar15.com/content/page.html?id=186 Rotation speed in the Greenhill formula is, of course, related to muzzle velocity. You did not specify your barrel length. A 24" bbl will stabilize at 1:8 twist , but a shorter 16" bbl may need 1:7 twist for the same bullet. Also, note that a SS109 steel core 62 gr bullet is going to be longer than a 62 gr lead filled FMJ so one 62 gr may stabilize and another 62 gr of different config. may not. |
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Thanks crap didn't think bout checking there thanks! It's 16" 1:9 twist 69gr stabilize so Hopi.g the 75's do as well but dought it. 62's are gtg or at least the ss109's Quoted:
Check over at the AR-15 / Ammunition forum FAQ section: "What twist..." for a good discussion on the subject. http://www.ar15.com/content/page.html?id=186 Rotation speed in the Greenhill formula is, of course, related to muzzle velocity. You did not specify your barrel length. A 24" bbl will stabilize at 1:8 twist , but a shorter 16" bbl may need 1:7 twist for the same bullet. Also, note that a SS109 steel core 62 gr bullet is going to be longer than a 62 gr lead filled FMJ so one 62 gr may stabilize and another 62 gr of different config. may not. |
| Just glanced at the faq and looks like up to 77 if your lucky. That sure be nice but ill have do some measuring just for interest when I get home. Really need get 1:8 barrel but for now ill wing it . Imo a sub " group @ 100 yards is less important than 1-2 well placed shot when hunting is the goal |
but does powder selection effect stabilization ? Would a load work up at or near max speed up enouph to make a difference?
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heavier the bullet the slower the burn rate you want.
I always work up through the full range sometimes the sweet spot is near max sometimes a little over sometimes well below. for deer you're really wanna do some testing at a pretty decent range, how close can you get to a deer that will also let you know how well you are stabilizing. It sounds like your doing ok even with those 75s a lot of the time the actual twist rate of the barrel will be faster or slower than what it's marked. considering your barrel doesn't like anything under 55 gr I'd wager it's in the faster category. |
| Generally speaking it takes a lot of velocity to make up for an improper twist rate, usually more than you have availible. 1:9s will often stabilize 75gr class lead cored bullets, not always though, also it will not always be revealed by keyholing, sometimes the groups grow in a non-linear manner, 1MOA @ 100 becomes 3MOA @ 200 with no other explanantion. Match bullets can work for hunting but are not ideal, weight is not everything. I'd take the TSX in any weight or any other bullet designed for consistent expansion over them. |
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