Forster Ultra Micrometer Seater Die - little help?

[thefitter]

I set up my Forster Ultra Micrometer Seater Die today and set my first batch of bullets. For the most part all the rounds were coming in at 2.87 but I had one or two that would come in at 2.865 or 2.88

Not sure why. Does the Forster measure off the base or the shoulder?

All the brass was once fired FGMM, FL sized and trimmed in a Giruad. Now I will say that the rounds could have been fired in different weapons.

Where am I losing my consistency? Thanks

 

[InTheWeeds]

Re: Forster Ultra Micrometer Seater Die - little help?

Where are you measuring from? THe meplat or the ogive?

 

[thefitter]

Re: Forster Ultra Micrometer Seater Die - little help?

Sorry I should have said OAL. The meplat.

 

[JeffinTX]

Re: Forster Ultra Micrometer Seater Die - little help?

None of the seating dies seat off the meplat, or the very tip of the bullet. The seating stem is generally cone shaped and will contact the bullet slightly below the meplat. The chamber, or more properly, the lands of the rifling does not care about the tip of the bullet, but where the bullet is full diameter, or the ogive. So, the way to measure properly is to measure the ogive to cartridge base. For that, you need to get a comparater which is of the correct caliber for your cartridge. If you are loading HPBT bullets, there will be a slight variance in the bullet length due to the way a HP bullet jacket is swagged into the lead core, sort of like how the foil wrapper goes around a Hersey's kiss. But again, that little difference in the meplat isn't really that critical. Again, the ogive to base length is what determines the distance to the rifling, the resizing of the brass or trimming the brass OAL has no bearing on this. One other thing, .308 spec COAL is 2.80", so if you go over, make sure that its not too long to fit in the magazine or have problems feeding, etc. Most .308 bullets tolerate jump just fine.

 

[thefitter]

Re: Forster Ultra Micrometer Seater Die - little help?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 7x57</div><div class="ubbcode-body">None of the seating dies seat off the meplat, or the very tip of the bullet. The seating stem is generally cone shaped and will contact the bullet slightly below the meplat. The chamber, or more properly, the lands of the rifling does not care about the tip of the bullet, but where the bullet is full diameter, or the ogive. So, the way to measure properly is to measure the ogive to cartridge base. For that, you need to get a comparater which is of the correct caliber for your cartridge. If you are loading HPBT bullets, there will be a slight variance in the bullet length due to the way a HP bullet jacket is swagged into the lead core, sort of like how the foil wrapper goes around a Hersey's kiss. But again, that little difference in the meplat isn't really that critical. Again, the ogive to base length is what determines the distance to the rifling, the resizing of the brass or trimming the brass OAL has no bearing on this. One other thing, .308 spec COAL is 2.80", so if you go over, make sure that its not too long to fit in the magazine or have problems feeding, etc. Most .308 bullets tolerate jump just fine. </div></div>

Thank you. I have a comparator en route. I'm loading as long as I can for a AICS magazine which seems to be right at about 2.87

I have not determined my max for feeding yet which probably sounds ass backwards. But I figure I can drop them a little more if need be. I'm reading a lot but I'm also winging it a bit.

You know re loading would make a pretty good night class to take at JC. It's way more complicated than I ever thought. Although it's probably like anything else, there are the hacks and then there are the anal retentive OCD Monk types.

Thanks

 

[John L]

Re: Forster Ultra Micrometer Seater Die - little help?

Try this for an educational exercise. Take your calipers and measure some bullets, base to tip. You will see a variance in them.
When you get your comparators after seating some loaded rounds measure them. You will still see some minor variations but to a much smaller degree. Forester dies are some of the best. Dont get to hung up on a .001 or.002 difference, your gun will never know.

 

[thefitter]

Re: Forster Ultra Micrometer Seater Die - little help?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 7x57</div><div class="ubbcode-body"> Most .308 bullets tolerate jump just fine. </div></div>

Then why is everyone always talking about using maximum OAL?

I ordered a Hornady Lock-N-Load Overall Length Gage and measured my chamber. I got 2.959 - .040 = 2.919 but that won't fit in my mags so I'm using 2.87

 

[Rthur]

Re: Forster Ultra Micrometer Seater Die - little help?

Thefitter, you should check out alpha 2 mags. They measure 2.985 interior length. This is a aics style mag btw. Rthur

 

[Headgear]

Re: Forster Ultra Micrometer Seater Die - little help?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I ordered a Hornady Lock-N-Load Overall Length Gage and measured my chamber. I got 2.959 - .040 = 2.919 but that won't fit in my mags so I'm using 2.87</div></div>


I'm confused about your chamber depth. I also have a Hornady OAL gauge and my chamber is 2.212 at the ogive. Are you using a comparator or just measuring to the meplat (tip in Indiana talk) of the bullet? Like was said above, there can be larger differences at the tip but you do need to know both. One to see where you are off the lands and the other to see that they will feed. If you are only measuring to the tip, remember that different bullets have different lengths from the ogive to the tip. I'll bet I'm preaching to the quire. Oh well you never know who else may read it and need the info.

I also use the same seating die and have noticed those small differences but I figured a little fouling in the chamber could probably exceed that. I did have the top of the die come loose just a little one time and got some inconsistent readings. you may want to check that if you haven't already.

 

[thefitter]

Re: Forster Ultra Micrometer Seater Die - little help?

Meplat. My comparator comes today maybe. When I got the OAL gauge I did not understand that I needed to measure off the meplat.

I'm thinking though that it does not matter because the dimensional restraints of the magazines preclude me from going long enough anyway.

You know I also assumed that the Sierra Match Kings were held to a tighter manufacturing tolerance. I'm surprised that the "best" bullet is not more exact considering how exact many reloaders are.

Thanks for the advice!

 

[Fuzzball]

Re: Forster Ultra Micrometer Seater Die - little help?

"..why is everyone always talking about using maximum OAL?"

Well, many BR guys seat touching the lands and it sure sounds 'knowledgeable', so why not talk? Of course a BR rifle (and ammo) is a LOT different from others but what's a few little details like that?

Fact is, MOST common rifles and ammo will shoot best with a jump from 20 thou to the lands out to as much as five times that much!

The biggest single factor in an accurate bullet is jacket consistancy. If the jacket isn't good nothing else will make the bullet good. Sierra uses excellant jackets.

 

[InTheWeeds]

Re: Forster Ultra Micrometer Seater Die - little help?

WHen you use that comparator, you life will become much easier.. I never measure OAL from the meplat unless I need to know the max length I can go in a mag. Luckily for me, my AR30 mag can handle almost a 3" bullet