Need alittle help with my OAL

[MrM4]

I am working on a load for a Rem 700 AAC-SD that I had blue printed, lapped and recrowned. 20 in" 1/10 twist. Currently I am looking using a 168 seirra match king and either 4895 or varget. I would preffer this load to fit in the mag well.

I am trying to find out what OAL to use, as with all guns each gun has it own favorite. So far this is what I know.

Magwell will allow for a OAL of <span style="font-weight: bold">2.825</span>
I used the split case neck and found out the round contacts the lands at <span style="font-weight: bold">2.862</span>
That leaves me with about <span style="font-weight: bold">.037</span>worth of jump.


Is it ideal to seat bullets out as far as possible with out contacting lands (staying back a few thousands of course) or is it better to stay around the 2.800 that many books list as the OAL? There are alot of threads with guying using a long OAL for better groups while others are talking about .030-.05 worth of jump and still getting good groups. Do the groups tend to improve as you set the bullet forward?

If it depends on the gun what is the best method figuring out the ideal OAL for your rifle? I figured I would try a few powder variation during R&D for the load but I just wanted to know what you guys think about where to start with the OAL.

All input welcome,
Thanks!

 

[oldfatguy]

Re: Need alittle help with my OAL

In reality the OAL doesn't have a very precise realtionship to where the ogive contacts the lands, close but not exact. The distance from the ogive to the bullet meplat (tip) will vary.

So, get yourself one of the comparitors and measure from the cartridge base to the ogive for a more reliable reference.

Remmys seem to all have very long throats. Makes it tough to get close to the lands and fit the rounds into the mag.

OFG

 

[Gene Poole]

Re: Need alittle help with my OAL

Use OCW to find a node with your powder of choice and your OAL set to spec (2.800), then once you've got your node, vary the seating depth from abour 2.795 out to your max to lands in 0.005 or 0.010 increments until you've got the tightest groups.

 

[hugo121175]

Re: Need alittle help with my OAL

Every rifle will be a little different with regards to OAL. I have a load that shoots exceptionally for my 270wsm that is jammed into the lands, and then I have a load for my .284 that has .050" jump that bugholes ten rounds at 100yds..... Myself, I would not be worried about Mag Length. I, personally, would be more concerned with what load rifle shoots well.

Have you read this?
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1713419#Post1713419
Edited to add this: http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1705470#Post1705470

 

[MALLARD]

Re: Need alittle help with my OAL

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: oldfatguy</div><div class="ubbcode-body">In reality the OAL doesn't have a very precise realtionship to where the ogive contacts the lands, close but not exact. The distance from the ogive to the bullet meplat (tip) will vary.So, get yourself one of the comparitors </div></div>this guy knows what he's talking about
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MrM4</div><div class="ubbcode-body">Do the groups tend to improve as you set the bullet forward?</div></div>not exactly. The groups will change, perhaps a certain COAL your shooting produces a cicular pattern group that is about 1 moa, both horizontal and vertical. Perhaps a different COAL will produce a group with 1.5 moa vertical and .5 moa horizontal spread. Which is better depends on your application. <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MrM4</div><div class="ubbcode-body">If it depends on the gun what is the best method figuring out the ideal OAL for your rifle?</div></div> Find OBT/OCW, then test COAL , .005 increments is good. With your distance to the lands, loading from the magazine will (probably) handicap you, in terms of accuray.

 

[MrM4]

Re: Need alittle help with my OAL

Thanks for all the replys and links!

 

[Aimsmall55]

Re: Need alittle help with my OAL

Good luck. Throats are looonngg on most of those rigs