POI left me wondering????
03-12-2011, 03:01 PM
#1
Guest
Posts: n/a
POI left me wondering????
I did some shooting two days ago and then again today. Same rifle, same bullet ,same primer. The only difference was I used 777 pellets the first trip just to get it on paper and not spend a lot of time. I got the gun sighted in somewhat to where I wanted it. So today I decided to try the load that I had planned on using in the gun, providing of course it likes the load.My goal was to fine tune.
So everything was exactly the same except I used 120 gr 777 loose powder instead of 100 gr ( 2 pellets)
Bullet on a clean barrel was pretty much the same as the pellets. The next shots were lower but excellent group with holes touching. All shots at 100 yards.
I was sure that the POI would be higher with the 120 gr of loose than with the 2 pellets. As it turned out the shots were about 3 inches lower but like I said an excellent group.
The only reason I can think of that would cause the loose powder to have a lower POI was that I dehydrated the pellets for 2 hours at 120 degrees because they had been open for so long and my basement is exceptionally humid from the clothes dryer. The loose powder I did not dehydrate. Maybe the loose powder had lost some power or the pellets increased performance from the dehydrating.
Any of you guys have a theory?
So everything was exactly the same except I used 120 gr 777 loose powder instead of 100 gr ( 2 pellets)
Bullet on a clean barrel was pretty much the same as the pellets. The next shots were lower but excellent group with holes touching. All shots at 100 yards.
I was sure that the POI would be higher with the 120 gr of loose than with the 2 pellets. As it turned out the shots were about 3 inches lower but like I said an excellent group.
The only reason I can think of that would cause the loose powder to have a lower POI was that I dehydrated the pellets for 2 hours at 120 degrees because they had been open for so long and my basement is exceptionally humid from the clothes dryer. The loose powder I did not dehydrate. Maybe the loose powder had lost some power or the pellets increased performance from the dehydrating.
Any of you guys have a theory?
03-12-2011, 04:07 PM
#2
Nontypical Buck
Join Date: Dec 2009
Location: Yucca Valley,Ca
Posts: 2,496
I did some shooting two days ago and then again today. Same rifle, same bullet ,same primer. The only difference was I used 777 pellets the first trip just to get it on paper and not spend a lot of time. I got the gun sighted in somewhat to where I wanted it. So today I decided to try the load that I had planned on using in the gun, providing of course it likes the load.My goal was to fine tune.
So everything was exactly the same except I used 120 gr 777 loose powder instead of 100 gr ( 2 pellets)
Bullet on a clean barrel was pretty much the same as the pellets. The next shots were lower but excellent group with holes touching. All shots at 100 yards.
I was sure that the POI would be higher with the 120 gr of loose than with the 2 pellets. As it turned out the shots were about 3 inches lower but like I said an excellent group.
The only reason I can think of that would cause the loose powder to have a lower POI was that I dehydrated the pellets for 2 hours at 120 degrees because they had been open for so long and my basement is exceptionally humid from the clothes dryer. The loose powder I did not dehydrate. Maybe the loose powder had lost some power or the pellets increased performance from the dehydrating.
Any of you guys have a theory?
So everything was exactly the same except I used 120 gr 777 loose powder instead of 100 gr ( 2 pellets)
Bullet on a clean barrel was pretty much the same as the pellets. The next shots were lower but excellent group with holes touching. All shots at 100 yards.
I was sure that the POI would be higher with the 120 gr of loose than with the 2 pellets. As it turned out the shots were about 3 inches lower but like I said an excellent group.
The only reason I can think of that would cause the loose powder to have a lower POI was that I dehydrated the pellets for 2 hours at 120 degrees because they had been open for so long and my basement is exceptionally humid from the clothes dryer. The loose powder I did not dehydrate. Maybe the loose powder had lost some power or the pellets increased performance from the dehydrating.
Any of you guys have a theory?
03-12-2011, 04:11 PM
#3
Nontypical Buck
Join Date: Dec 2006
Location: Minnesota
Posts: 2,037
I have had that exact thing happen Chet. I think that you always get some muzzle jump when shooting and with more velocity, the bullet is gone before the muzzle jumps and hence you get a lower point of impact. At least that is what I was told when it happened to me. Those two pellets are really only the same as about 85 grains of the loose.
Then to test it I used 85 grains of the loose and I got the same POI as I got with the pellets.
Have you shot that pretty gun of yours yet Chet?
Then to test it I used 85 grains of the loose and I got the same POI as I got with the pellets.
Have you shot that pretty gun of yours yet Chet?
Last edited by flounder33; 03-12-2011 at 04:15 PM.
03-12-2011, 04:37 PM
#4
Nontypical Buck
Join Date: Aug 2008
Location: Rapid City, South Dakota
Posts: 3,732
I have had that exact thing happen Chet. I think that you always get some muzzle jump when shooting and with more velocity, the bullet is gone before the muzzle jumps and hence you get a lower point of impact. At least that is what I was told when it happened to me. Those two pellets are really only the same as about 85 grains of the loose.
Then to test it I used 85 grains of the loose and I got the same POI as I got with the pellets.
Have you shot that pretty gun of yours yet Chet?
Then to test it I used 85 grains of the loose and I got the same POI as I got with the pellets.
Have you shot that pretty gun of yours yet Chet?
03-12-2011, 04:44 PM
#5
Giant Nontypical
Join Date: Nov 2005
Posts: 6,585
This is not unusual the lighter load sometimes shoots higher because the recoil has a chance to lift the barrel some before the bullet is out of it, where as the higher velocity load expels the bullet before the recoil has a chance to be effective.
03-13-2011, 06:52 PM
#6
Spike
Join Date: Mar 2008
Location:
Posts: 27
i have had that exact thing happen chet. I think that you always get some muzzle jump when shooting and with more velocity, the bullet is gone before the muzzle jumps and hence you get a lower point of impact. At least that is what i was told when it happened to me. Those two pellets are really only the same as about 85 grains of the loose.
Then to test it i used 85 grains of the loose and i got the same poi as i got with the pellets.
Have you shot that pretty gun of yours yet chet?
Then to test it i used 85 grains of the loose and i got the same poi as i got with the pellets.
Have you shot that pretty gun of yours yet chet?
yep, exactly!
03-13-2011, 08:29 PM
#7
Giant Nontypical
Join Date: Mar 2010
Posts: 5,605
Without chrono data and the powder variables, im really not sure why that would happen. I consider powder as part of the ejecta weight. Since most of the powder doesn't usually leave the barrel, IMO recoil starts at ignition and probably ends in under 2 milisec.
The only test ive tried on POI vs powder charge was with BH209. 100gr vs 110gr at 100yards. The 110gr load was consistently 3/4-1" higher in my 45 with a 200gr SST. That was on a sled too so it not apples to apples.
The only test ive tried on POI vs powder charge was with BH209. 100gr vs 110gr at 100yards. The 110gr load was consistently 3/4-1" higher in my 45 with a 200gr SST. That was on a sled too so it not apples to apples.
