which OAL to start with?

[Wiking-76]

Hi there,

In a few days I'll start reloading for my Browning X-Bolt (.308 Win).
The most important question right now is, with which OAL I should start with.

The Nosler Reloading Manual states an OAL of 2.810 for the 165gr Accubond, but my headspace-measurements result in 2.933 (although the magazine will only take cartriges up to 2.895).

Should I start with SAAMI-specs to develop my first load and experiment with seating-depth later?

Other options would be to take the max. length the magazine can accomodate OR to work the mag over for max. OAL.

Regards,

 

[wfjames22]

Re: which OAL to start with?

Real question is do you want to use the mag or not??

Headspace has nothing to do with seating depth. Accubonds should shoot fine with a decent amount of jump (loaded to mag length), at least thats what I have experienced.

If I was in your shoes, I would load to 2.885 and see how that works. Good luck on your load development.

 

[sobrbiker883]

Re: which OAL to start with?

You need the measurement of where the leade meets the ogive then you will know what you are actually jumping.

'lil tip-if that is greek to you, stick with the published OAL.

 

[Wiking-76]

Re: which OAL to start with?

...since it is my hunting weapon, the magazine is an essential part.

The bullet (ogive) contacts the lands at 2.311 (with max OAL 2.933), Ogive at magazine-length is 2.278 and with SAAMI the value is 2.192.

Thus the jump would be 0.119 (from SAAMI-value to contact).
At magazine-length the jump would be 0.033.
Which one sounds more promising to you?

Thanks for the answers so far.

 

[Timo Turl]

Re: which OAL to start with?

I'd suggest you load to a little under mag length (ie 2.885) and concentrate on producing consistent loads there. Loading closer/into the lands might improve accuracy but it probably won't make a huge difference for hunting.

 

[Wiking-76]

Re: which OAL to start with?

...sounds good, TJ.
Although I use this rifle for hunting, I spend quite some time on the range with it.
I'm kind of a freak when it comes to accuracy - tight groups boost my ego and give me confidence when taking shots on a living creature.

Is there any possibility that the deviation from the specs in my reloading manual will result in dangerous pressure?

Thanks for the input.

Regards,

 

[Fuzzball]

Re: which OAL to start with?

First, you need to understand that all SAAMI specs is the minimum leade of a chamber. From that, it's clear that there is a maximum practical OAL but the gun manufactors can make their leade as long as they wish. If they do more, the extra jump to the rifling is generally called "free bore", meaning an unsual portion of the bore is free of rifling.

All reloaders should then understand that BOOK OAL is simply what the book makers used to develop the published data, book OAL it is NOT a law nor a specification. Fact is, IF we had to duplicate book figures, we would be reduced to loading by presets, not custom loading for what our rig needs for best performance, so we may as well use factory ammo.

Now, it's usually easiest to start load development at the longest practical OAL and find the best shooting charge with the powder and primer you wish. Then tweak the accuracy by seating deeper in smallish steps, like maybe 5-10 thou, until you find the best shooting OAL range, often some 10-15 wide in which depth has no effect on groups. Load your ammo in the middle of that range and all will be well, you won't have so many unexplained 'flyers' due to slight seating variations. In my experience most sporter rifles do best with a jump between 20-50 thou but some like twice that, or more!

A manual is a very helpful guide but NEVER presume it is anything more. The book makers can only tell us the results they got with their rig while using their components. They don't know a thing about ours so WE are the final determining check factor in what we can safely shoot in our rigs.

 

[Timo Turl]

Re: which OAL to start with?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wiking76</div><div class="ubbcode-body">...sounds good, TJ.
Although I use this rifle for hunting, I spend quite some time on the range with it.
I'm kind of a freak when it comes to accuracy - tight groups boost my ego and give me confidence when taking shots on a living creature.

Is there any possibility that the deviation from the specs in my reloading manual will result in dangerous pressure?

Thanks for the input.

Regards, </div></div>

If it were me, I'd start afresh at that OAL and load up from mins in small increments. I'm sure you'll find an accuracy node along the way but as always, check each and every load before and after firing.

 

[sobrbiker883]

Re: which OAL to start with?

At least .010-.015" under mag length for reliable field feeding.

Work up from 5% under max published (10% if OAL is a lot shorter than the OAL in the book) in .3gr increments, you'll find something it likes along the way.

I wouldn't sweat tweaking the OAL much, too much is at stake when a round doesn't feed with quarry in sight.