OAL issues for imitation M2 ball

[kenny223]

Help me out here Please... I am loading 30-06 for use in a Garrand using 150 gr. Hornaday FMJ over 47.0 grs. IMR 4895. My problem is that if I set the bullets into the Cannelure the OAL is well below the recommended 3.30 inches. Having measured many different rounds of Mil. Surp. M2, and finding it well longer than 3.30 in., I am reluctant to set these heads into the cannelure.

 

[RidgwayCO]

If it helps any, Hornady recommends (in their 6th Edition reloading manual), a COL of 3.185" with this bullet (#3037, 150gr BT-FMJ) in the M1 Garand. The longest COL shown with any of their bullets in the M1 Garand section is 3.240".

 

[kenny223]

Thanks for that info.... I was afraid to deviate on the OAL fearing pressure issues on a 60 year old rifle.

 

[RidgwayCO]

Just remember to start low and work up slowly. Use medium burning-speed powders and don't try for fire-breathing loads out of your Garand, or you can bend the operating rod. The Hornady 6th Ed. manual has a special section on the Garand, just to help you avoid this possibility. (I'm pretty sure it's in the 7th Ed. as well).

 

[steve4102]

Published OALs are NOT recommendations. They are only a guide to tell you what they used. Hell, some manuals don't even list and OAL. Set them to what works best for you and your rifle.

From AA and Ramshot.
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.

 

[rg1]

I've shot them in my Garands using Hornady's recommended oal from earlier manuals which puts the cannelure out in front of the case mouth 3.258-3.260" and their latest shorter recommended oal 3.185" which puts the cannelure at the case mouth. All loads were with 47.5 grains of IMR 4895 using LC, REM, and Win cases with RP 9 1/2 primers. No problems with feeding or pressure and with my shooting I could see no difference in accuracy. I prefer the shorter length with the cannelure at the case mouth for crimping.

 

[RidgwayCO]

Use a maximum load at a shorter COL than what the testers used, and you're asking for a high pressure event.

Hell, some manuals don't even list and OAL.

That's true. And I won't buy or use them just for that reason.

 

[steve4102]

Use a maximum load at a shorter COL than what the testers used, and you're asking for a high pressure event.

Got any hard evidence to back this up? We are talking bottlenecked rifle here not straight walled handgun.

 

[Sport45]

I am reluctant to set these heads into the cannelure.

Welcome to The High Road!

If you're going to crimp (I don't for my M1), seat the bullet to the cannelure. If you don't crimp, make sure you have at least one caliber, 0.308", for the neck tension to hold on to. In either case start with the published MINIMUM LOAD and work up to an acceptable accuracy. Don't try to make a mag out of the old girl and don't expect to find a load giving 1 MOA groups.

 

[USSR]

If you're going to crimp (I don't for my M1), seat the bullet to the cannelure. If you don't crimp, make sure you have at least one caliber, 0.308", for the neck tension to hold on to.

+1. Simply ignore the crimp and load them with 0.3" of the bullet in the neck (not counting the boattail when using boattail bullets).

Don

 

[RidgwayCO]

Use a maximum load at a shorter COL than what the testers used, and you're asking for a high pressure event.

Got any hard evidence to back this up?

Well, I don't have any photos of destroyed rifles, if that's what you're asking. I think it's fairly intuitive, but let's run an example through QuickLOAD.

Assume you're using a Hornady 165gr SP bullet in the .30-06 loaded to a COL of 3.338" (.308" of the bullet is seated in the case). QuickLOAD computes a maximum load of 53.9gr of Varget, giving 2821 fps at a pressure of 59,811 psi (just under the SAAMI maximum average pressure of 60,000 psi). Now decrease the COL to 3.140", and the computed pressure goes up to 67,973 psi. Will this blow up your rifle? Probably not (although it could cause excessive pressure signs in some rifles). Is it over-pressure? Definitely. And over time I expect it will cause excessive wear and tear on the rifle.

Sure, the result is not as dramatic as a bullet getting deeply set into the case upon feeding in a handgun semi-auto round, but the physics are the same. Reduce the size of the boiler-room and pressures go up. Until I purchased QuickLOAD, I had no idea of the consequences arbitrarily shortening a COL could have.

I don't expect this will satisfy you, but it's the best I can do for now.

(STANDARD DISCLAIMER: QuickLOAD is software written by fallible humans; it is NOT divinely-inspired Scripture. It may or may not reflect conditions in the real world. Never trust any load data from the internet including (especially) mine. Start low and work up slowly, looking for signs of excessive pressure. You are responsible for your own health and safety. The loads described are purely hypothetical, and may not be safe in your weapons.)

 

[rg1]

Agree that shortening overall length increases pressure. But in the Garand with IMR 4895 powder and 150 grain bullets such as the Horn. 150fmj loading at normal Garand charges of 46-48 grains of powder, it already is 2-4 grains less than maximum 30-06 charges depending on data sources. Noted that Garands requires charges designed for it's operating system so as not to damage the rifle but just saying that at 47 grains of IMR 4895 seated to Hornady's shorter recommended oal will not increase pressure enough to damage the rifle or create overpressure with any case or rifle I've shot them in. Seated to 3.258-2.260" the bullet is about 2/3 into the neck and seated to 3.185" it will be at the bottom of the neck not protruding into the case reducing case volume. Quickload is an interesting valuable reloading tool. Don't know why I've not obtained the program yet?

 

[steve4102]

QL fails to take into consideration distance to the lands or throat dimensions. The longer the throat/farther from the lands, the less pressure. Think Weatherby, 6.8 SPC Spec II and 5.56 vs 223.

Here is a good article by Barnes. Scroll down to "From the Lab" You will note that reducing OAL in most instances reduced pressure.
http://www.barnesbullets.com/resources/newsletters/september-2007-barnes-bullet-n/

Then there is this. Notice the shorter the OAL the less pressure.


You can also go here and read comments by John Barsness (Mule Deer) on OAL and pressure. Scroll down to post #13.
http://www.24hourcampfire.com/ubbth...cs/5084340/all/Asking_Mule_Deer_about_Full_Le

 

[longdayjake]

I agree that a shorter OAL does not mean that you will get more pressure. Don't depend on quickload for anything other than giving you a good starting point. I have found that QL often is WAY off in relation to velocity predictions. QL is not a substitute for load development nor for a chronograph.

As far as m2 ball goes, you are using the wrong bullets. The M2 Ball bullets have a shorter boat tail as well as a totally different ogive. However, you could probably load the Hornadys with the case mouth on the cannelure and use the same powder charge as the m2 without having any problems.

 

[steve4102]

LDJake, just a quick question, do you have and use QL or are your comments geared more towards what others have posted?

 

[USSR]

As far as m2 ball goes, you are using the wrong bullets. The M2 Ball bullets have a shorter boat tail as well as a totally different ogive.

Actually, M2 ball bullets are not boattail bullets at all, but rather are flat base bullets.

Don

 

[Mals9]

I loaded the Hornady's to an OAL of 3.250, this put the edge of the case at the bottom of the cannelure, and I did not crimp. I used 47 gr of IMR 4895 in Greek surplus brass. The functioned very well and were accurate.

Mals