OAL paradox...

[gmbailey21]

I have a (hopefully) quick question in regards to OAL

Something that has me scratching my head is the Max OAL is listed at 2.570 for the .444 Marlin cartridge, but the load data has a Min OAL of 2.62. (300 gr Hornady XTP) So I can't do one without violating the other.

Loaded to the first (lower) cannulure, the OAL is about 2.67, to the second is about 2.52.

The OAL Min/Max is from the current lee loading manual. Which should I go by in my load?

Thanks in advance!

 

[Noveldoc]

If you have 2 cannelures, the bullet probably was designed for 2 different cases. I use some military pulled .308s that also have 2 cannelures, one for 7.62 NATO and one for 30-06.

Maybe if you research the bullet maker's site you can find which is which for your case. Or find a pic of a loaded round with your bullet and see if there is an exposed cannelure.

Tom

 

[otrman]

Min OAL of 2.62

Is probably a misprint, should be MAX OAL of 2.620, according to Hodgdon's site. But both Lyman's 49th and Sierra manual list MAX. OAL as 2.570. It has been my experience that Hodgdon tends to load a hair long. If this load is for a lever gun I would go with the shorter of the two.

 

[steve4102]

Set it where ever it works best for you. From Accurate Powder,

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must
be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of
the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.

 

[Kernel]

Those 300 gr XTPs have two cannelures because some .44 Magnums can be loaded to a longer than SAMMI COAL. Ruger revolvers and single shots like the Thompson-Center Contender, in particular.

A longer COAL allows more powder to go into the case, resulting in higher velocities.

In order to avail yourself of this performance boost, you must first have a firearm that can chamber and function with a cartridge longer than SAMMI spec. Most lever actions won’t.

If I had a .444 Marlin that would function with the longer round, then that's what I'd use. You should easily be able to realize a 50 - 150 fps velocity increase with no pressure penalty.

 

[Steve C]

If you have specific data from the manufacturer of the bullet you are using its best to use their data since they developed it with the exact same bullet. This will generally give you the best results. Data from non specific sources and other manufacturers are used as a simple guide but not as well determined. Whichever data you use you need to make sure it works in your particular gun.

 

[gmbailey21]

Thanks for the replies, I'll check with Hornady and see what they recommend.

As of now I have them loaded long, with the second cannulure exposed. I'll be using them in a handi-rifle, so I don't think that them being slightly long should hurt anything (single-shot), but when or if I end up with a sweet Marlin Lever Rifle in this caliber, I guess I might be unable to use them beyond single shot.

I was concerned that if I went down to the second cannulure, .005 shorter than min OAL listed for the load, that the pressure might be increased and I might be in for an unpleasant surprise. Reduced case capacity would mean higher pressures, right?

If it is a misprint, then Lee has it misprinted in both their Load Book and their data that they include with their dies. Can anyone post something from another manual? IE Lyman or Hornady?

Thanks!

 

[gmbailey21]

Is probably a misprint, should be MAX OAL of 2.620, according to Hodgdon's site. But both Lyman's 49th and Sierra manual list MAX. OAL as 2.570. It has been my experience that Hodgdon tends to load a hair long. If this load is for a lever gun I would go with the shorter of the two.

For the Lyman and Sierra, is that for a 300 gr bullet?

I see the Hodgdon's site shows OAL (assumed max) at 2.620:

300 GR Hodgdon H4198 .430" 2.620" 38.5 1917 36,200 CUP 42.5 2082 42,500 CUP

This if for H4198, I'm using IMR, so the actual powder load max is less (I'm using 40 at the moment, can't find good data for IMR 4198, but that's another post...), but the OAL is likely the same (all are listed at 2.620 for 280+ grain bullets on Hodgdon's site).

So sounds like I should load down to the second cannulure for 2.52 as long as it doesn't create a compressed load (shouldn't). Will still check with Hornady to be on the safe side.

 

[ranger335v]

Steve in #4 has the right info.

Many (relitively) new guys look at book OALs as if they are a LAW that can't be deviated from without a KABOOM or at least the bolt handle falling off. Nonsense. Most old manuals listed no OAL data at all, they knew we would have to find our own. Seems the book makers efforts to help has actually caused more confusion than it's eliminated!

As Steve points out, what's in the books is what the bookmakers used to develop their data, no more than that. Surely none of us think that book charge data is gospel truth, we should ALL know it has to be tested in our firearm for confirmation. Ditto the OAL. Find what feeds and chambers in your own firearm, otherwise you will only be loading for theirs!

Get the right OAL for your rifle and then develop your best load. Then tweak the seating for best accuracy.

 

[gmbailey21]

Thanks, I've read that in other areas, but as I'm still pretty green, I'm not sure exactly how OAL can affect pressures, either in the cartridge, or in the barrel.

A call to Hornady resulted in their tech stating that the bullet should be 2.535, which would be at the very lower part of the second cannulure. He said the 2.670 might be alright as long as it isn't contacting the rifling, but recommended going shorter. I guess I'll see how it fits at the longer cannulure, and then go from there.

Thanks!

 

[Kernel]

Gmbailey, cartridges for single-shot rifles don’t need to be crimped. Seat the bullet as far out as you like. Ignore the cannelures, altogether. In fact, conventional wisdom is - crimping bullets for single-shot rifles is bad for accuracy.

Everything else being equal, longer cartridges have higher performance potential because they have a larger powder space. The farther “out” the bullet is seated, the more volume there is BEHIND the bullet. The hand loader can put more powder into the case. More powder makes the bullet go faster.

But wait, there’s more! All things being equal, a larger powder space does another thing - it LOWERS pressure. This little benefit makes the whole thing work. Life is good when the laws of thermodynamics become your friend.

Put it all together: load a longer cartridge, that holds more powder, which results in higher velocities, at acceptable pressure levels. As a hand loader, that last part there is REAL important to understand.

However, there are some cautions. There’s some things you’ll need to check out first. Skills needed in determining how long a cartridge you can load. Considerations. Such as - the distance between the bullet and the lands in your rifle’s barrel.

If you don’t know how to do all that stuff, you need to research it, cuz I don’t have time and space to explain it all here and now.

I don’t know about Handi-Rifles, but I have a number of Contender barrels and I can say that Thompson-Center is VERY generous in it’s barrel dimensions (some might even say TOO generous). In other words, you can seat the bullets as far out as you want. To the point were the bullet is practically falling out of the case mouth - and still not be touching the lands.

A longer COAL can transform cartridges like the 7-30 Waters and the .375 Winchester. I wouldn’t be surprised if it did the same for your .444 Marlin.

 

[gmbailey21]

Thanks for the confirmation! I do need to build a rig for figuring out the max OAL for guns, just need to think about it a bit more, get some measurements, and head to the hardware store.

Loaded out to 2.67, the bullet is not contacting the rifling, so I'm going to leave this batch at that COAL. Only bad thing is that if I get a Marlin Lever .444 down the road they may not fit beyond a single shot (if even that due to rifling in the barrel), but that's alright. Is there anyone out there with a Marlin Lever .444 that knows how long a bullet you can reliably cycle through it and not contact the rifling?

I'm not trying to test the strength of the gun, just put bambi down the first time. I do wish I had gotten a Handi Rifle earlier, they now have an extractor instead of an ejector, so a second shot is pretty unlikely in PA woods.

Thanks again for weighing in!

 

[gmbailey21]

Update

As per Hornady's suggestion, as the OAL used for their data was 2.535 I ended up going with that and 39.5 Gr of the IMR 4198.

I think the first cannulure would give me less pressure and more accuracy, but I need to figure out how to safely work some data up for that, likely with a chrony.

Thanks!

 

[rcmodel]

2.570" SAAMI standard is as long as will work in a lever-action.

The 300 grain Hornady bullet has two crimp cannulures.

The short one is for .444 lever-actions, and the longer one is for .444 single-shots, and .44 Mag revolvers & rifles that will handle the longer length.

rc

 

[gmbailey21]

rcmodel 2.570" SAAMI standard is as long as will work in a lever-action.

The 300 grain Hornady bullet has two crimp cannulures.

The short one is for .444 lever-actions, and the longer one is for .444 single-shots, and .44 Mag revolvers & rifles that will handle the longer length.

rc

Do you know of any load books with different loads listed for the different load lengths that account for the different pressures?

 

[rcmodel]

No I don't.

I had really paid little attention to it prior to your question, as I have never owned a .444 Marlin. or loaded the 300 grain XTP in my .44 Mag Marlin either.

rc