Is it possible that the ogive could vary .030" on different lots of Bergers?

[Gene]

Woods, I have had a set of those for about 40 years; no mfg. name on them, and I had no idea who made them or where I got them. They make the measurement only to OAL and each bullet tip still varies. But it does give you an idea as to where you should set the bullet in a dummy round and start the process of finding the lands.

BTW to the OP: I shoot a lot of Bergers in .22, 6mm and .308 cals. I have never seen them vary by .030". You might consider sorting by bearing surface length.

 

[gunner69]

Help me out with the math then. This group was taken from 302 yards. The five on the left are all extremely close with two almost in the same hole. The flyer was on the right. Many thanks.

 

[trebark]

Help me out with the math then. This group was taken from 302 yards. The five on the left are all extremely close with two almost in the same hole. The flyer was on the right. Many thanks.

The group might be .5" wide, but it's ~1.875" tall (measured center to center not outside edge). It is that largest dimension that determins the group size. In this case, the five shot group (minus the flier) is about .6moa

 

[Mikecr]

Well, throwing any one out, still leaves ~an inch of grouping vertical, and higher accuracy vertical(from center of mark).
This does not come out to 1/4moa at 300yds.

Gene, you misunderstand the tool's use.
While it is true: "They make the measurement only to OAL".
It doesn't matter what OTHER bullet tips might cause & measure.

You make a dummy round to OAL with THE bullet used in measure, and set YOUR standard comparator on it to determine YOUR max OgvOAL(log it).
From that point, all reference from & into lands is taken to your max OgvOAL.
The fly in the mix is still ogive radius variance, but that is another tool.

 

[gunner69]

It is 1.34" tall. What does that make it? Walk me through precisely how you calc. I want to make sure I'm doing it right. Is there some kind of universal procedure/formula? Many thanks again.

 

[Mikecr]

If 1.34" tall is TRUE group(max outside measure minus one bullet hole) then MOA is:
=(1.34/(302/100))*0.954929659= 0.424

That would be MOA of grouping.
For MOA of accuracy, apply formula to max outside measure to center of mark(bullseye).

 

[trebark]

If 1.34" tall is TRUE group(max outside measure minus one bullet hole) then MOA is:
=(1.34/(302/100))*0.954929659= 0.424

That would be MOA of grouping.
For MOA of accuracy, apply formula to max outside measure to center of mark(bullseye).

Realize I am about to split a hair here, but....

The calculation above is inches-per-hundred-yards. True moa would go like this....

1moa at 100 = 1.047" making 1moa at 302yards is 3.02*1.047= 3.062

So, 1.34/3.062 = .438moa

 

[Pdvdh]

Thanks woods. My e-mail inquiry has been sent. If I don't receive a response by next Tuesday, I'll try the phone number.

Hopefully Randy is still producing and selling these units. For $25, or even $35, it isn't worth me trying to improve upon his idea and product.

An update here - Just in case anyone was wondering; I did try to purchase one of these tools from Randy, but was never able to receive any response from him. I either had bad/outdated contact information, or he was non-responsive.

 

[Mikecr]

Hairs I can split;
1 MOA is actually 1.047197551 IPHY (at least)
1.047197551*3.02 = 3.16253660402
1.34/3.16253660402 = 0.423710510827506

I round this to 0.424 moa

 

[Aldon]

MAybe one of you who have the tool that is in Woods picture can confirm but it looks very similar to Sinclairs seating depth tool, 749-004-650SB ($32.95)

 

[gunner69]

Gunner69, you need new calipers or something..
That GROUP isn't 1/4moa(unless you're picking best 3 out maybe), and nowhere near 1/4moa of ACCURACY.
Just sayin,, you should check it again.

If 1.34" tall is TRUE group(max outside measure minus one bullet hole) then MOA is:
=(1.34/(302/100))*0.954929659= 0.424

So when I said "approximately 1/4 moa I was off by .17 so not that much. I wouldn't characterize that is "nowhere near". I'm going out today to see what I get at 600 and 1000 yards. Thanks for the calc help and have a good Memorial Day Weekend - God bless our troops and the USA.

 

[Mikecr]

MAybe one of you who have the tool that is in Woods picture can confirm but it looks very similar to Sinclairs seating depth tool, 749-004-650SB ($32.95)

I have both.
They're not the same.

The R-P tool allows measure from a jammed bullet tip to boltface. It does this from the muzzle end.
The Sinclair tool basically takes the same approach as the Stoneypoint/Hornady-copy method, from the back of an action.

Big differences in accuracy of measure;
The Sinclair 'guide' is loosely resting against the action's extraction ramp(angled surface) and/or rattling around in the bolt arm channel. THIS IS BAD.
The R-P tool stops are resting against a very flat and perpendicular crown. THIS IS GOOD.
The Sinclair tool's measure is completely dependent on head space of a case, which is more difficult to consistently set than seating itself.. THIS IS BAD.
The R-P tool takes the measure directly to bolt face, which does not vary. THIS IS GOOD.

The R-P tool method is far more accurate.
And the Sinclair video/instructions for their tool are wrong in several respects.
Never assign credit to the words of a gun-writer, politician, or sales man..
That said, Sinclair does offer good tools and I really like them. But not all of their stuff is good (a lot of junk lately), and they sell em just the same.

 

[Mikecr]

So when I said "approximately 1/4 moa I was off by .17 so not that much. I wouldn't characterize that is "nowhere near".

Well, if you manage to get your ~1/2moa gun shooting to actual ~1/4moa, come back and let us know just how much 'off' ended up being.
I know with many guns, that difference could get very costly -for me (Ahab's whale).

 

[woods]

An update here - Just in case anyone was wondering; I did try to purchase one of these tools from Randy, but was never able to receive any response from him. I either had bad/outdated contact information, or he was non-responsive.

I called the number that was in my previous post 318-424-7867 and Steven (Randy's son) answered and said that this was the "office" number and that they are indeed still selling the tool. He also gave me Randy's mobile (?) 318-464-8906 if I wanted to talk to him directly.

Also "as far as he knows" the e-mail is still the same and that was [email protected] (there is an underscore in betwee the r and reeves which is obscured by the automatic underscoring of a website or e-mail generated by this website)

Also "as far as he knows" the price is still $25.00. Sounded like a young kid and very polite.