# Stretching your ARs OAL



## airforcehobit (Aug 6, 2008)

I am new the the AR world in the sense that i hunt/target shoot with one now instead of just work. I am also new to reloading. From what i gather longer OAL can be a good thing for a couple reasons. Less jump to rifling making better alignment with the bore and more case capacity.

I saw that olympic fit a 22-250 in to a milspec AR-15 platform so i dug around the internet to find out how. I did not find out anything other then how to fit some long rounds in an ar other then the VLD conversion from DPMS of going to a bob sled (single shot) and how to mod a mag to fit 2.35 OAL if you look at most mil spec mags to will see the case of the mag is doubled and tack welded in the front. I simply removed the front of the mag and smoothed it inside and out i used a 20 round mag and did not extend the cut any lower then the mag well to keep out dirt and to help maintain is regitity. I took them to the range and they worked fine but no better groups were found.

Anyone else try this?

Whats your 2 cents


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## specialpatrolgroup (Jan 16, 2009)

airforcehobit said:


> From what i gather longer OAL can be a good thing for a couple reasons. Less jump to rifling making better alignment with the bore and more case capacity.


I am not a grizzled relaoding vet, so please dont mistake my thoughts as expert advice,

Yes and no, if you measure the OAL of the chamber to the lands you can adjust your depth based on that distance and find the distance that is the most accurate. Often that is any where from 40 to 20 thousands from the lands, Factory ammo since it has to chamber in a ton of differnt guns can often 60 thousands or much shorter. If you do not know the proper length to seat the bullet at, you can end up shoving it too far into the lands and not allowing enough room for the neck to let go, creating a pipe bomb. If you are just starting off, first worry about finding the right charge\bullet your rifle likes and getting your process down, once you have a combination that works thn try seating at 40 thousands off, then 30 then 20 to see how it effects accuracy. This is measuring from the bullets ogive, not the tip, the ogive is the part that actually touches something first when fired.

As far as case capacity, rule of thumb, the less empty room you have, the more consistant you will be, you can sometimes controll this by selecting a powder that will use up the appropriate amount of space. But the variation from seating .006 to .002 isn't that much of a change.

Also remember, for autoloaders it is recomended you crimp your cartridges, so you will be seating on the cannelure.


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## specialpatrolgroup (Jan 16, 2009)

Also should have mentioned, lenght measured from teh tip of the bullet is meaning less, look at getting a Hornady bullet comperator to attach to your calipers.


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## airforcehobit (Aug 6, 2008)

thanks


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## farmerj (Jun 19, 2004)

specialpatrolgroup said:


> Also should have mentioned, lenght measured from teh tip of the bullet is meaning less, look at getting a Hornady bullet comperator to attach to your calipers.


Really?

I read that and thought, "Huh?"

so in looking at it, I can find a lot of drawings that show OAL base to tip, but little or nothing that shows base to Ogive.
http://www.gmdr.com/rcbs/rcbstext7.htm

The only thing I found that showed base to ogive was a drawing for a .276 pederson.


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## Savage260 (Oct 21, 2007)

Base to tip is pointless when talking about finding the lands because the ogive is where the lands are going to contact the bullet. Base to tip is VERY important in dealing with ARs because you have a max OAL that the magazine allows. You can't go over that unless you single load.

I load to just under max allowable mag length and try to find a load that works. I found a couple loads that work really well in the AR I built. Some are over max some fit in the mag. They don't have to be at the lands or close to be good shooters if your rifle likes it. I have a bolt gun that I have to do this for also.


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## farmerj (Jun 19, 2004)

I understand you don't go to the tip if you are measuring to go off the lands. You have to go to the bearing surface of the bullet.

But even to do that, you should have a case OAL gage...

But even most of them have you measure Base to tip.
http://www.gunsamerica.com/blog/the-hor ... al-gauges/

And yes, I have seen instructions for both ways.
http://www.6mmbr.com/catalog/item/1433308/977259.htm

It just proves you need to have a system that works to give you the information that you need and stick with it.

Even more important is to understand the difference between the two and understand that someone else might be measuring it differently than you do.


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## airforcehobit (Aug 6, 2008)

I have run god knows how many loads(mostly factory) through my r-15 and i can't find anything the stays under and MOA I have the best luck with partition handloads (short ojive) so i thought it would favor a shorter jump gave it a shot but i think i need to get the gauges so i can record and quantify my findings. got the cart ahead of the horse i guess.


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## djkost (Mar 20, 2010)

Before going to all that what is the twist on the barrel? In one of mine it is 1-7 and the other is 1-8. Both these will shoot a 60 or 68 grain bullet that will fit in your mag without altering it. Both twist are for heavier bullet not light bullets. Check the twist then load the right weight bullet and see if your groups tighten up.


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## jk3hunter (Dec 29, 2010)

I have been reloading for my AR for a few years now. I have never had to crimp my bullets and I should half inch groups or better. I'm shooting the 50 grain V max just in case you were wondering. Works like a charm and is VERY accurate. Powder is Varget which is very insensitive to temperature and also is very accurate


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