Extended OAL testing with 240g/.44mag

[kawalekm]

I wanted to increase the performance of my .44 magnum for short-range deer hunting with my 1894 Marlin. I determined that a 240 grain hollow-point could be seated out significantly further than the 1.610” OAL listed in manuals. I determined that a cartridge OAL of 1.850” just touched the rifling of my barrel, so I wanted to see how much extra performance I could get by seating bullets further out.

I first determined though that a 1.850” OAL would NOT feed through my action. The longest OAL that would feed reliably was 1.750” but I decided to add .1 inches to OAL. I made some dummy rounds without a primer and filled them with water to determine internal volume. A OAL 1.610” cartridge had an internal volume of 1.52 grams (1.52 cc at 25C), while the OAL 1.710” volume was 1.74 cc, a 14.5% increase in volume. This extra volume suggests that I MIGHT be able to increase powder capacity by 14.5%. Assuming that 24.0 grains of H110 is maximum for a standard cartridge, I MIGHT go as high as 27.5 grains of H110 with a 1.710” OAL cartridge.

Since the cannelure of Remington bullets is positioned for 1.610” seating, a long bullet might recoil out of the brass during firing. I solved this by applying a second cannelure 0.120” below the factory one with a CH canneluring tool. My finished cartridges look like this.

http://i141.photobucket.com/albums/r55/kawalekm/1750length240grainbullet.jpg

I tested 5 rounds each at 23.0 to 27.0 grains of H110 at 1.710” and 23.0 grains of H110 at 1.610” as a control. All were fired in ELD brass with CCI 350 primers. I measured velocity at 10 feet, accuracy at 50 yards, and case head expansion. Here are my results.


Charge Velocity Group size Case head/change Comments

Control 1744 1.90” .458”/.000 factory load

23.0 gr. 1717 1.94” .458”/.000 1.5% velocity reduction

23.5 gr. 1740 2.04” .457”/-.001

24.0 gr. 1776 1.86” .458”/.000 Birth of our nation

24.5 gr. 1818 1.87” .459”/+.001

25.0 gr. 1825 2.23” .458”/.000

25.5 gr. 1864 1.51” .458”/.000

26.0 gr. 1887 1.87” .459”/+.001

26.5 gr. 1901 1.50” .459”/+.001 1920 ftlb KE

27.0 gr. 1949 1.35” .459”/+.001 Severe muzzle blast, too hot!

I expected a greater increase in velocity, but achieving 1900 fps was OK. Going by the rule that case head expansion should not be greater than .001 inch, it looks like even the maximum load I tested is OK. I didn’t see any really flat primers in this run, so I didn’t evaluate them. The 27.0 grain load FEELS too hot, judging from the muzzle blast and the level of recoil. It just felt like the right place to stop. From its level of performance, and good accuracy, I am considering the 26.5 grain load for future deer hunting.

[35remington]

Sounds like the extra cannelure and seating the bullet out were a sensible way of increasing bullet capacity and making sure the bullet was securely seated, so the experiment was worthwhile.

You've got a soundly reasoned way of doing things.

A couple of comments.

The cannelure was more worthwhile as a means of securing bullet position (and making sure it didn't move under recoil forces in the tube magazine) and making sure a deep seated bullet over an increased powder charge did not occur. A "long bullet might recoil out of the brass during firing" is not a concern, mostly because the round is being fired, and it can't "recoil out of the brass" because the primer impulse and powder ignition are pushing it forward. What you did was make sure it arrived in the chamber at the proper overall length and not telescoped into the case because it was not crimped in the cannelure. Upon firing, if the bullet is at the longer position, holding the bullet in place is no longer relevant because it's going forward no matter what.

I thought your adding a cannelure to secure the bullet was very sensible.

The proper rule when measuring case head expansion (if you are in fact actually measuring that) is less than an additional half thousandths case head expansion is acceptable, but I think you are applying that rule to something else entirely here than that to which it was intended. That was meant to apply to rifle cases running at higher pressures that have a thicker case head.

True case head expansion is very difficult to measure with the rim in place even with a blade micrometer with a reduced diameter spindle. A conventional micrometer or caliber has much too thick of a jaw or spindle to measure pistol case head expansion, and so does even a blade micrometer. The rim gets in the way, and the "case head" is very, very thin in pistol cartridges, being much thinner than a rifle case head. Usually, you're measuring case wall expansion due to this thinness, not the case head. In this instance, then, you've got to distinguish your rule of "less than one thousandth additional case head expansion" (which you're probably not measuring) from an additional one thousandth case wall expansion (which you probably are measuring).

They're very different things. Section a .44 magnum case sometime and observe how thin the case head is, which is below the case wall expansion ring and above the rim. It's quite thin, and doubtful that you're measuring it alone. Most likely you'll also measuring case wall, which does not apply to the "one thousandth (actually half thousandth) or less expansion" rule in judging a maximum load. Further, when the actual case head (if you're truly measuring it) expands a thousandth of an inch further than before, you're way past SAAMI max for a 44 magnum, especially in a rear lockup lever action.

Case head expansion is more relevant for determining a maximum load in a case that has a thicker rifle type case head and also higher maximum allowed pressure. You're probably measuring relative expansion at the case wall expansion ring (and should be measuring to ten thousandths, which is difficult to do but necessary) and a thousandth of an inch difference is hard to place on a scale of relative pressures. I note that some of the measurements went backwards with the increased charge, which is how measurements sometimes go when actually measuring case wall expansion.

Regardless, seating bullets out in a straight walled case is a proven way to increase case capacity and in so doing either lower pressure or obtain increased velocity at the same pressure and your methodology was very sensible. The actual pressure obtained is the only question left unaswered.

Further reloading and shooting, which I have no doubt you will do, will help answer the question satisfactorily.

[mike in co]

as a reference point, in quickload your 1900 fps with a 240 hp with a 20"(?) bbl is 39k psi............10 PERCENT OVER SAAMI MAX.

IT IS JUST A TOOL.....not necessarily true in your rifle.

if you want more top end performance, go up in weight...keep the velocity reasonable.

i dont hunt....
i do shoot steel at 50 yds. i shoot the 288/296 hp at 1160 fps...it will easily do more safely.
about 1350 easily out of a 20"bbl at only 33k psi or so, and nearly identical knock down power to your hot load.

just info...no whining
mike in co

[35remington]

Mike, does that Quickload calculation include the seating out of the bullet in the case?

If it's 40.000 psi or less, that should still be within the strength of the brass or gun, but it is certainly over the SAAMI maximum as you point out.

[mike in co]

Mike, does that Quickload calculation include the seating out of the bullet in the case?

If it's 40.000 psi or less, that should still be within the strength of the brass or gun, but it is certainly over the SAAMI maximum as you point out.


yep i used his oal.

and all i was pointing out was is there is a safer way to get what he "needs" vs what he wants

mike in co

[kawalekm]

Thanks 35 for your explaination of the difference between the case heads and walls. What you said about the cannelure is also correct. I was worried about the unfired rounds remaining the the tube that might be dislodged.

Mike, thank you for your comments also. It looks like the extended OAL is not worth the trouble of loading for me. If I had miraculously gotten 2000fps at 36000psi I might. But, it's probably a lot easier to just load my rounds the regular length with 24 grains of H110 and not worry about it. A deer will never know the difference.
On the the next project,
Michael