I posted a version of this question earlier but did not phrase things very succinctly. I would like to build a lightweight 375. My goal is a 22-23� barrel and I�m trying to decide between a 375 Dakota and 375 RUM for one of the project guns (there will be two, one on a Mauser which will not accept the RUM without a lot of work.)

Is the added case capacity of the 375 RUM over the Dakota wasted on a short barreled rifle? I haven�t found a (free) program for calculating expansion ratios, nor do I know for sure if this number helps determine barrel length needed to burn X% of a given powder charge etc. I don�t want to significantly increase muzzle blast if the performance increase is minimal.

Is there an objective way to answer this question? I hear of guys having great luck with 22� and shorter 339 Winchesters, It seems like, without doing the math, that the 375 Dakota ratio in a similar barrel length should be similar (roughly 10-15% increase in both bore diameter and case capacity).

I appreciate the input.

For ball park expansion ratio numbers, add the volume of the case to the volume of the useable barrel (bolt face to muzzle minus the length of the case) and divide by the volume of the case. (If you want to get fussy you need to account for the throat and land&groove dimentions)

The bullet gets most of its energy in the first few inches of the barrel. By the time you are at 20", you're only gaining 35-50 fps per inch, at at 29", it's 15-18 fps per inch. Yes, expansion ratio matters. But not that much after the first several inches.

First of all muzzle blast will approximate the 16" guns of the USS Wisconsin in either case.....both are equal and bad!!!

I'd estimate the velocity of the .375 Dakota in a 22" barrel to be 2,600'/sec with a 300 grain soft and the velocity of the .375 RUM in a 22" barrel and same bullet to be 2,750'/sec.

I agree with Denton.....shorten the barrels to 20" and only loose another 100 (or so)feet/sec. Even at 19" you have more than the venerable old .375 H&H.

Wear hearing protection.......and a jock strap!!!!!

Snowcat,

I ran your specs on Load from a Disk internal ballistics program. Here are the results using H414 powder and Barnes 300 grain X bullets for all loads. I don't know if this is representative of your intentions but is just a comparison.

375 Dakota----------2361fps using 23" barrel
68.6grains-----------2345fps using 22" barrel

375RUM-------------2550fps using 23"barrel
81.3grains----------2527fps using 22"barrel

Hope this is some help.

LOL!!

Vapodog is exactly right on the muzzle blast issue. Get a chin strap for your hat.

I think it was somebody on this board that said the sole purpose of a rifle is to give enjoyment to its owner. So, if whatever you build gives you enjoyment, it turned out right.

Unless you've done a lot of custom guns--and I have not--it's hard to really visualize what you are going to get. I think that the back-and-forth on the board can be a great help.

Far be it from me to tell you what you want, but I side with Ray on this one. My rifles range from a 20" '06 to a 29" Swedish Mauser. The 29" Mauser and my 27" Finnish Mosins are by far my favorites for general shooting. They are heavy to carry in the field, but that's what grown kids are for! The short barrel does give you a more "nimble" gun, one that you can quickly point. A long barrel is easier to be accurate with.

Just my opinion, but I think short barrels belong on the lighter calibers. My 18" 223 is just right.

Longer barrels belong on bigger calibers. The longer barrel reduces recoil, and muzzle blast, and makes a gun that I think is easier to hold steady.

I rarely ever shoot my Browning '06. It has a short barrel. If you put the muzzle brake BOSS on it, it is an extremely unpleasant gun to shoot. My custom 24" '06 is a lot more fun to shoot.

One question you might ask yourself: Is this gun going to spend a lot of time at the range, shooting for pleasure? Or is it going to spend time stomping around in the brush? You won't enjoy shooting a large caliber, short barrel at the range. It might be an advantage in the brush.

My own personal experience, which nowhere begins to match others on this forum, tells me that a big factor in all this is the type of sighting used. If you put glass on top of it, it probably won't make a noticeable difference due to barrel length. However, iron V sights or peeps, it can make a difference. I use mainly peep, and will say that the longer sight radius the better. JMHO on this one.

The advantage lies not in ballistics, but in accuracy.