I am starting to reload for my new rife a 300 win mag. I put a Nikon buckmaster scope on it with BDC. Assuming the scope is shipped with its adjustments centered vertically and horizontally I sighted in with 180 federal sp ammo. It was hitting about 8 inches high so I end up moving the scope down that 8 inches to get it sighted in. Today I shot my first reloads through it which was 180gr. Sierra GK with 72 and 73 gr H4831sc. They hit about 8 inches low and and inch left from where the factory ammo sighted in at. I know this is probably a stupid question but can anyone tell me why this is? Is the velocity that much lower causing impact low that much? Also I shot 2 groups 1 with 72 gr and 1 with the 73 gr. They all impacted the same. cutting holes. except on first group one impacted about an inch higher and on second group one impacted about an inch lower but all others were cutting holes. Could these flyers be from not being on right amount powder? If I gradually increase it and groups tighten up will it eliminate the flyers? Thanks. Trying to learn on this 300 wm. There were no pressure signs at all. No sticky bolt, no markings on headstamp, primers look good and aren't flattened or cratered. I'm thinking I will reloads next batch in 74 gr and 75 gr. Alot info I come across have used 75gr of h4831 with success in this caliber and bullet weight
Reloads and Factory Point of Aim
- Thread starter Whiteymin
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Telekinesis
Member
Honestly there could be a lot of factors behind your reloads having a different point of impact than the factory ammo that you used to sight in with. You're using different bullets and even though they are the same weight, they will fly differently. Powder is also a big piece of the puzzle, you are almost assuredly using a different powder than the factory ammo you used which means it's profile (in regards to burn rate, pressure, resulting velocity, etc) are going to be different. Both of those will definitely change the POI of a round when compared to factory ammo.
Just expect that every time you change something about the load, you are going to have a different point of impact. The change could be small or large depending on what you change (and how much it is changed) but don't expect different loads to perform the same.
Not sure what to tell you about the fliers. How may rounds were you shooting in each group? A 3 round group with one "flyer" could just be a load that doesn't group well with 2 lucky shots. A 20 round group with one flyer could be an issue with consistency in loading, or something simple like a shooter error. As you do more load development you will hopefully find a load that minimizes group size. I'd also recommend smaller changes in powder weight once you get to the point of fine-tuning your load.
Also, good luck getting those BDC marks to line up with your ammo. As you change the load (dofferent bullet, BC, velocity, etc) your points of impact at the ranges indicated will change as well. Your round will still pass the hash mark at some range, but very likely not the one marked. For example, your 400 yard mark on your reticle could happen at 382 or 413 yards (and it won't be a linear change either).
Just expect that every time you change something about the load, you are going to have a different point of impact. The change could be small or large depending on what you change (and how much it is changed) but don't expect different loads to perform the same.
Not sure what to tell you about the fliers. How may rounds were you shooting in each group? A 3 round group with one "flyer" could just be a load that doesn't group well with 2 lucky shots. A 20 round group with one flyer could be an issue with consistency in loading, or something simple like a shooter error. As you do more load development you will hopefully find a load that minimizes group size. I'd also recommend smaller changes in powder weight once you get to the point of fine-tuning your load.
Also, good luck getting those BDC marks to line up with your ammo. As you change the load (dofferent bullet, BC, velocity, etc) your points of impact at the ranges indicated will change as well. Your round will still pass the hash mark at some range, but very likely not the one marked. For example, your 400 yard mark on your reticle could happen at 382 or 413 yards (and it won't be a linear change either).
Steve in NC
Member
Whiteymin,
I've fired many rounds of 300 Win Mag and very similar wildcats at long range. You are onto a great combination of powder and bullet weight with the 300 Win Mag. H4831 and R22 are great powders in the Win Mag.
The easiest way to think of differences of POI and tuning loads is to think of a rifle as a tuning fork. Tuning the up/down out of a load is the difficult part. May I ask which rifle you are shooting? A 8" vertical difference in loads is not unheard of but it is on the larger side also. Just wondering if you are using a pencil thin barrel or something that could cause excess barrel whip making it harder to tune?
Then the other thing that causes me concern is when you mentioned the loose flyers in your H4831 reload group is that they went vertical also. Also you didn't mentioned if you were using LR Mag or std LR primers in your reloads? One thing I've done in the past to tune out vertical for long range was change from LR Mag primers back to Std LR and then bump your load backup more (As long as your pressure signs are on the good side). I was shooting Fed215 with 72gr of R22 with 180gr bullet at 1000yds and getting about 15" of vertical. I changed to Fed 210s and changed my load up to 75gr of R22 with the same 180gr bullets and cut the vertical in half. I've done this many times. A lot of people think because your case has magnum stamped into the head that you NEED to use magnum primers. And that really isn't the case. Now when the temps get relly really cold... like in single digit then you might need a mag primer.
We did a test one time with a 338 Lapua Mag Improved shooting 95-98gr of powder using Fed 210 primers (Std LR) and the first misfire didn't happen until the temp was at 6F. I shot that cartridge in BR competition for several years and used LR primers in the summer time and never had any issues. Better SD numbers on the chrono also.
Let us know how you progress. I'll do my best to help. But you have the basic for an awesome load in the 300 Win Mag.
Steve
I've fired many rounds of 300 Win Mag and very similar wildcats at long range. You are onto a great combination of powder and bullet weight with the 300 Win Mag. H4831 and R22 are great powders in the Win Mag.
The easiest way to think of differences of POI and tuning loads is to think of a rifle as a tuning fork. Tuning the up/down out of a load is the difficult part. May I ask which rifle you are shooting? A 8" vertical difference in loads is not unheard of but it is on the larger side also. Just wondering if you are using a pencil thin barrel or something that could cause excess barrel whip making it harder to tune?
Then the other thing that causes me concern is when you mentioned the loose flyers in your H4831 reload group is that they went vertical also. Also you didn't mentioned if you were using LR Mag or std LR primers in your reloads? One thing I've done in the past to tune out vertical for long range was change from LR Mag primers back to Std LR and then bump your load backup more (As long as your pressure signs are on the good side). I was shooting Fed215 with 72gr of R22 with 180gr bullet at 1000yds and getting about 15" of vertical. I changed to Fed 210s and changed my load up to 75gr of R22 with the same 180gr bullets and cut the vertical in half. I've done this many times. A lot of people think because your case has magnum stamped into the head that you NEED to use magnum primers. And that really isn't the case. Now when the temps get relly really cold... like in single digit then you might need a mag primer.
We did a test one time with a 338 Lapua Mag Improved shooting 95-98gr of powder using Fed 210 primers (Std LR) and the first misfire didn't happen until the temp was at 6F. I shot that cartridge in BR competition for several years and used LR primers in the summer time and never had any issues. Better SD numbers on the chrono also.
Let us know how you progress. I'll do my best to help. But you have the basic for an awesome load in the 300 Win Mag.
Steve
Wreck-n-Crew
Member
Pretty dramatic POI?POA shift for the same bullet weight IMHO. Sounds more like something is loose or barrel is touching something. Double check the scope mounts, scope rings, action screws, and Barrel clearance. Also did you adjust the parallax? (if it has a parallax adjustment)By the way what rifle is it?
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