How to establish a starting OAL

[Powerslide91]

Ok, I'm new to reloading but want to make it my next step in this sport. I have been reading the forums as I can, and have had the help of a few local USPSA reloaders to get going. My goal is to work up a 9mm minor load for my XD9 tactical (factory barrel).

I started with getting several published loads and recommended loads from manufactures and this forum. I tried my first build of a couple rounds recently on a borrowed 650. I used Precision Bullets 115gr FP in mixed range brass, and had selected what I had thought was a reasonable starting OAL of 1.14". The rounds drop freely into a case gage, but when I drop them into my barrel they need pressure to get them fully seated, and then need to be pryed out. Now with some further research, I see reference to needing a shorted OAL with these bullets, on the order of 1.10".

So in gerneral, does anyone have any tips and tricks for how to work up an OAL if I don't have published info I trust? I've seen reference to wanting the OAL to be as long as possible. And I have seen reference to the bullet just engaging the lands of the barrel. Do I go back and make some dummy rounds and start short, make a couple, and see if they drop in and out of the barrel freely? Is any resistance ok? When I drop factory FMJ RN into the same barrel, it goes in and out freely, so I assume that is what I should try to duplicate.

Lastly, I tested a round out of my batch, and the length was ~ 1.1450" before, and after dropping the slide on it it measured 1.1395, so ~ 0.006" reduction. Typical? Should I test fire these rounds or scrap them and try something shorter?

Thanks for any info!

[Jonathan Taliani]

Not directly addressing your question, but have you measured your crimp? That sounds like a lot of set back from being chambered once.

[The_Vigilante]

A good place to start is measure the OAL of a factory round which drops in your barrel with no resistance.

[Skydiver]

A good place to start is measure the OAL of a factory round which drops in your barrel with no resistance.

That's with the assumption the same bullet profile for the factory round and the reloaded round.

I found out the hard way that my the OAL I was using for Montana Gold 147gn truncated cone, wouldn't work using Rainier 147gn round nose.

[Powerslide91]

Not directly addressing your question, but have you measured your crimp? That sounds like a lot of set back from being chambered once.

That is a bit of the reason I mentioned it, I was a little unsure if it was crimp or the fact the round is hitting the lands too much. The recoil spring in the gun is the factory part. I checked each round in a gage block, and inspected the crimp area for what it is worth. Should the crimp be measurably different than the diameter of the brass?

A good place to start is measure the OAL of a factory round which drops in your barrel with no resistance.

That's with the assumption the same bullet profile for the factory round and the reloaded round.

I found out the hard way that my the OAL I was using for Montana Gold 147gn truncated cone, wouldn't work using Rainier 147gn round nose.

Yes, exactly what I ran in to. My loaded rounds are actually slightly shorter than the factory ammo I mentioned, but the difference (I believe) is all in the bullet shape.

[The_Vigilante]

Yep, have to compare apples to apples and oranges to oranges. The bullet ogive can make a lot of difference!!!

[biggdawg]

your on the right track. 1.145 is too long so start shortening the oal till the bullet will drop in and seat in chamber correctly

with no resistance. go small amounts then when one chambers correctly subtract .005 and load a couple to see how they cycle and feed.

[Jonathan Taliani]

Crimp should typically be in the neighborhood of the bullet diameter + ~ .020 to account for the thickness of the brass.

[98sr20ve]

So you start with a round that is crimped properly and too long for your barrel. You then do the drop test every time you shorten the length a little till it fits YOUR barrel. Then you done.

[fltbed]

In auto loading pistols, the cartridge OAL is critical for functioning. Load the bullet to short and the round could nose dive on the feed ramp and jam the slide.

Load it to long and it may be longer than the magazine will allow or it could hang up on the ejection port or you can wind up with the dreaded three point jam (round in contact with the breach face, feed ramp and the top of the chamber) or worse get the bullet stuck in the rifling.

A side effect is that, as you shorten the OAL you decrease the size of the combustion chamber inside the case which will increase pressures.

I use this method to determine the guns OAL for whatever bullet I‘m loading first:

Things you’ll need:

1. Dowel rod that fits down your bore. (cleaning rod will work in a pinch)

2. Exacto knife, razor blade or scribe.

3. Dial calipers

With the action closed, insert the dowel rod through the muzzle till it’s resting against the breach face and scribe a line on the rod at the muzzle.

Now insert the bullet you plan on loading into the chamber and hold it against the rifling with something. (another piece of dowel rod, cleaning rod, etc.)

Reinsert the dowel rod till it’s resting against the nose of the bullet and scribe another line on it at the muzzle.

Measure the distance between the two lines and you now have the maximum OAL for that bullet in your chamber. I normally back off my OAL another .010 or, if it's real long, to the max OAL that will function through the magazine.

I know there are other ways of determining OAL that are more precise and more expensive, but I’ve always found this method more than adequate for my needs.

Once I know the bullets OAL in my gun, I’ll work up my load from there.

Hope this helps.

Jeff

PS I have found a lot of TC design’s that copy the ogive of Hornady’s XTP to require a really short OAL.

[CocoBolo]

Ok, this is my method:

1. Use a caliper to measure the distance inside from front to back of the magazine for the gun.

2. Size and deprime a case.

3 Bell the case.

4. Seat a bullet into the case .010 shorter than the measurement in #1.

5. Do just enough crimp to remove the bell on the case. (this allows the bull to still move.

6. With the barrel out of the gun put the test round in the chamber and push it all the way in gently till it is fully in postion aka brass is at end of hood.

7. Remove the round and measure it with a caliper.

You have not determined the maximum length that you could possible load with this particular bullet, subtract .010 and load a few test dummy rounds and try out the feeding adjust as necessary.

I didn't have a dowel.

[Powerslide91]

Good info, thanks for sharing your tips. I like the ideas of using a dummy round with a loose crimp, since that does account for the bullet profile. Maybe a little more work but worth it.

A big part of it for me was learning how much to back it off from the max possible.

Thanks!