question about point of impact - The Firearms Forum

johnlives4christ · 06-10-2009, 11:29 PM

okay. let me ask a kinda dumb type question.

okay if i have a gun, lets say a 9mm. and i shoot 115 grain winchester out of it on paper. and it hits say dead center. then i shoot 115 remington ammo out of it. will it still hit where i aim, or will the center of the group move?

i know differant guns prefer differant ammo for accuracy, but would the differant brands change points of impact or would it just change group sizing?

if i switch to 147 grain ammo. would the groups still be centered left to right, but just lower? or would it change completely?

reason i ask is this... i always have sighted my guns in... then stuck with the same ammo that i like, for that particular caliber. up until now when ammo is basically buy what you can when you can. i dont want to waste a mess of ammo to try it all out if anyone has any advice

~john

woolleyworm · 06-10-2009, 11:44 PM

Any change in a load component can result in a point of impact change. Different manufacturers use different powders, bullets, etc, too many variables to say that you could consistently get the same general grouping. Even with let's say 10 rounds, all case sized perfectly, charge wts exact, bullets all weighing the same and fired from a bench rest from a standard pistol at 50 feet...... you'll probably still get a round or two that wouldn't be in a tight group. ( my idea of a tight group at 50' bench rested would be under 3") handloading has been the only way i can get consistent repeatable groups, just my .02

Southern Boy · 06-11-2009, 08:21 AM

Yep, tho most manufacturers list thei drop @ yds, for a comparisom. If 1st bullet mfgr. says 0@ 40 yds, another say 0@ 50 hds , then you know if zero'd at 50 yds, bullet nfg. #1 will be a hair low.. When handloading, you change loads untill you get your most accurate groups, then use your drop info to account for different loads. Kind of confusing I guess, It will become second nature after time.Hope this helps.

TranterUK · 06-11-2009, 08:40 AM

The advice above is sound, and I dont have much to add.

In years gone by I carried a 9mm handgun, it was sighted to place rounds point of aim at 25 yards with 115gn FMJs. The problem was buying local ammo in different places with varied weights, types and makes. I always figured for defence, that is to say dinner plate groups at close range, it wouldn't make much difference. Clearly if your shooting targets, perhaps in competition, knowing where they are going and getting the best possible accuracy is all important.

Incidentally, not a dumb question at all....

carver · 06-11-2009, 12:11 PM

Quote:

Originally Posted by johnlives4christ

okay. let me ask a kinda dumb type question.

okay if i have a gun, lets say a 9mm. and i shoot 115 grain winchester out of it on paper. and it hits say dead center. then i shoot 115 remington ammo out of it. will it still hit where i aim, or will the center of the group move?

i know differant guns prefer differant ammo for accuracy, but would the differant brands change points of impact or would it just change group sizing?

if i switch to 147 grain ammo. would the groups still be centered left to right, but just lower? or would it change completely?

reason i ask is this... i always have sighted my guns in... then stuck with the same ammo that i like, for that particular caliber. up until now when ammo is basically buy what you can when you can. i dont want to waste a mess of ammo to try it all out if anyone has any advice

~john

As Tranter said if for SD, it don't matter that much since you are shooting CM, a traget about 8" - 10". For target shooting mixing and matching ammo will give you poor results. Every gun has it's favorites, find out which one your gun likes and stick to it if possible. Again, another reason to reload for target practice.

johnlives4christ · 06-12-2009, 05:25 PM

thanks for the advice already given. does differant loads normally impact only high or lower or do they impact left and right as well?

carver · 06-12-2009, 05:48 PM

Again, it depends on what your gun likes. It will always shoot one particular rd. (brand)better than almost any other. If you gun does not like the ammo you are feeding it at the time, it may shoot high, or low. It might shoot left or right.

"okay if i have a gun, lets say a 9mm. and i shoot 115 grain winchester out of it on paper. and it hits say dead center. then i shoot 115 remington ammo out of it. will it still hit where i aim, or will the center of the group move"?

If you are shooting Winchester 115 gr., and you are hitting dead center, then stick with it for target shooting, as well as SD. If you can't find Winchester, then shoot what you can find. It might not shoot as well on paper, but will work fine as a SD round. Remember, shooting bulls eyes is not going to much for your SD skills. These will be bettered only with practice drawing, and firing as quickly, and safely as possible, still being able to put your rounds CM.

Popgunner · 06-14-2009, 08:28 PM

You're going to have to test & confirm with your gun, ammo & your hold. Pistol point of impact is different than rifle point of impact especially regarding bullet weight. While rifles usually throw heavier bullets to a lower point it's common for pistols to throw heavier bullets to a higher point of impact. This is because heavier bullets have longer barrel time & the barrel rotates up noticeably while the bullet is still in the barrel. When a heavier bullet leaves a barrel pointing higher often the impact point is higher than a lighter bullet would have. Even two people with different holds can have different points of impact.

06-10-2009, 11:44 PM	#2
woolleyworm TFF Moderator/Host Join Date: Feb 2009 Location: SW Fort Worth Contributor Posts: 4,883	Re: question about point of impact Any change in a load component can result in a point of impact change. Different manufacturers use different powders, bullets, etc, too many variables to say that you could consistently get the same general grouping. Even with let's say 10 rounds, all case sized perfectly, charge wts exact, bullets all weighing the same and fired from a bench rest from a standard pistol at 50 feet...... you'll probably still get a round or two that wouldn't be in a tight group. ( my idea of a tight group at 50' bench rested would be under 3") handloading has been the only way i can get consistent repeatable groups, just my .02

06-11-2009, 08:21 AM	#3
Southern Boy V.I.P. Member Join Date: Jun 2009 Posts: 110	Re: question about point of impact Yep, tho most manufacturers list thei drop @ yds, for a comparisom. If 1st bullet mfgr. says 0@ 40 yds, another say 0@ 50 hds , then you know if zero'd at 50 yds, bullet nfg. #1 will be a hair low.. When handloading, you change loads untill you get your most accurate groups, then use your drop info to account for different loads. Kind of confusing I guess, It will become second nature after time.Hope this helps. __________________ "The 2nd Amendment is my "concealed carry permit"" Ted Nugent

06-11-2009, 08:40 AM	#4
TranterUK Advanced Senior Member Join Date: May 2008 Location: Cambridge UK Posts: 5,103	Re: question about point of impact The advice above is sound, and I dont have much to add. In years gone by I carried a 9mm handgun, it was sighted to place rounds point of aim at 25 yards with 115gn FMJs. The problem was buying local ammo in different places with varied weights, types and makes. I always figured for defence, that is to say dinner plate groups at close range, it wouldn't make much difference. Clearly if your shooting targets, perhaps in competition, knowing where they are going and getting the best possible accuracy is all important. Incidentally, not a dumb question at all.... __________________ DVC - Diligentia, Vis, Celeritas - Accuracy, Power, Speed. The light at the end of the recession tunnel IS a train coming the other way! Last edited by TranterUK; 06-11-2009 at 08:42 AM..

06-12-2009, 05:25 PM	#6
johnlives4christ Former Guest Join Date: Apr 2008 Location: Kentucky Posts: 3,828	Re: question about point of impact thanks for the advice already given. does differant loads normally impact only high or lower or do they impact left and right as well?

06-12-2009, 05:48 PM	#7
carver TFF Moderator/Host Join Date: Jul 2008 Location: DAV, Deep in the Pineywoods of East Texas, just west of Shreveport, LA Contributor Posts: 11,253	Re: question about point of impact Again, it depends on what your gun likes. It will always shoot one particular rd. (brand)better than almost any other. If you gun does not like the ammo you are feeding it at the time, it may shoot high, or low. It might shoot left or right. "okay if i have a gun, lets say a 9mm. and i shoot 115 grain winchester out of it on paper. and it hits say dead center. then i shoot 115 remington ammo out of it. will it still hit where i aim, or will the center of the group move"? If you are shooting Winchester 115 gr., and you are hitting dead center, then stick with it for target shooting, as well as SD. If you can't find Winchester, then shoot what you can find. It might not shoot as well on paper, but will work fine as a SD round. Remember, shooting bulls eyes is not going to much for your SD skills. These will be bettered only with practice drawing, and firing as quickly, and safely as possible, still being able to put your rounds CM. __________________ Y'all be safe now, ya hear! Lamentations Chapter 5: 1. Remember, O LORD, what is come upon us: consider, and behold our reproach. 2. Our inheritance is turned to strangers, our houses to aliens. 3. We are orphans and fatherless, our mothers [are] as widows. 5. Our necks [are] under persecution: we labour, [and] have no rest. 16. The crown is fallen [from] our head: woe unto us, that we have sinned! 21. Turn thou us unto thee, O LORD, and we shall be turned; renew our days as of old. Last edited by carver; 06-12-2009 at 05:53 PM..

06-10-2009, 11:29 PM	#1
johnlives4christ Former Guest Join Date: Apr 2008 Location: Kentucky Posts: 3,828	question about point of impact okay. let me ask a kinda dumb type question. okay if i have a gun, lets say a 9mm. and i shoot 115 grain winchester out of it on paper. and it hits say dead center. then i shoot 115 remington ammo out of it. will it still hit where i aim, or will the center of the group move? i know differant guns prefer differant ammo for accuracy, but would the differant brands change points of impact or would it just change group sizing? if i switch to 147 grain ammo. would the groups still be centered left to right, but just lower? or would it change completely? reason i ask is this... i always have sighted my guns in... then stuck with the same ammo that i like, for that particular caliber. up until now when ammo is basically buy what you can when you can. i dont want to waste a mess of ammo to try it all out if anyone has any advice ~john -->

06-14-2009, 08:28 PM	#8
Popgunner Advanced Senior Member Join Date: Dec 2005 Contributor Posts: 1,764	Re: question about point of impact You're going to have to test & confirm with your gun, ammo & your hold. Pistol point of impact is different than rifle point of impact especially regarding bullet weight. While rifles usually throw heavier bullets to a lower point it's common for pistols to throw heavier bullets to a higher point of impact. This is because heavier bullets have longer barrel time & the barrel rotates up noticeably while the bullet is still in the barrel. When a heavier bullet leaves a barrel pointing higher often the impact point is higher than a lighter bullet would have. Even two people with different holds can have different points of impact.