I knew this in the past but am at a loss now,,,with a 7mm-08 what would the approximate loss of FPS be from a 24 to 22 inch barrel.

I know it will not be exact but what is the norm?

Thanks PPosey

Every barrel is diff. but somewhere between 25-40fps per inch of bbl.

thanks

I have found 25 FPS as it increased when I had a longer barrel put on.

Posey, it depends on the size of the case. The little shorties like the 7mm/'08 lose less than '06 sized cartridges, and even less when compared to the maggies. For example, a .264 Win. Mag. with a 22" barrel is about equivalent to a 22" .270 Winchester, despite using 10+ grains more powder.

In your case, I'd predict that you will lose (approx) between 15 FP per inch to perhaps as much as 20 FPS per inch between 24 and 22" barrels....

quote:

---

Originally posted by El Deguello:
In your case, I'd predict that you will lose (approx) between 15 FP per inch to perhaps as much as 20 FPS per inch between 24 and 22" barrels....

---

Yup....agreed.....sure makes it hard to justify long barrels don't it.

Okay, what's your opinion on me cutting my 6.5x55 barrell from 24" to 20"??

The same 15-20 fps per inch??


Thanks

It's a function of velocity, the higher the velocity the greater the lose /inch .So 4" with a 3000 fps cartridge is going to be significant, while 6" off my 45-70 I didn't even worry about.

quote:

---

Originally posted by mete:
It's a function of velocity, the higher the velocity the greater the lose /inch. ...

---

I totally agree.

What has worked for me is to take 1%/inch of the Velocity.

For example, if you have a 26" barrel that is shooting a specific Load 3000fps and chop 1" off, I'd lower it 30fps and estimate it to now produce 2970fps.

Chop off another inch to 24" and take 2% off(60fps) to 2940fps.

The only real problem is it just doesn't account for the strange variations from rifle to rifle.

quote:

---

Originally posted by Mauser96:
Okay, what's your opinion on me cutting my 6.5x55 barrell from 24" to 20"??
Thanks

---

the 6.5X55 is a fine cartridge and if I wanted a 20" barrel I wouldn't care what the velocity loss was to be I'd just do it because that's what I wanted. The loss is not going to be noticed in any hunting you do. Some very fine factory rifles in .270, .30-06, .257 Rob etc have been produced in 20" barrels and used successfully. Ok you might loose 100'/sec.....will you ever notice it?.....will anything you shoot at notice it?

Thanks for the replies guys.

I'm considering cutting down my beloved 6.5 from it's 24" bbl to a 20" to make a more compact package for my daughter to use.

It's going to bring tears to my eyes to do it though.

I think I'll shorten the stock up first, make up some light loads and see what happens.
If necessary, I'll (GASP) make "the cut"

Thanks for all the info,,,

a slower powder would loose more speed as well eh?

I was figuring a loss of 50 fps max with a two inch cut from 24-22. I like a 22 inch barrel

quote:

---

Originally posted by Mauser96:
Okay, what's your opinion on me cutting my 6.5x55 barrell from 24" to 20"??

The same 15-20 fps per inch??


Thanks

---

Well, I lived in AK for three years, and while there, did all my hunting with a 25" barreled .375 H&H and a .270 Win. that had a 20" barrel. For some reason, the only times I came across game I wanted to shoot, I had that little M/S .270 carbine in my hand. It was loaded with 150-grain Nosler bullets with a MV of just at 2800 FPS from that short tube. It proved adequate for all game up to moose and large black bears.

I would not hesitate at all to bob your 6.5X55 to 20"! Remember the Swedish Mauser carbines? They were only a little over 17", but were real killers. I see no reason why yours at 20" would be any less adequate! You will lose 100 FPS OR LESS by cutting 4" off the 6.5X55.

One thing to remember about chopping that barrel off. It may seem a little handier in the garage (or where ever) but it really won't make that big of a difference in the field. One thing that will happen though, is it will be considerably louder when fired. I don't know if that will affect your daughters shooting skills, but it's something to think about. Once it's off, you can't put it back on.

Terry

M96..I have 2 sporters in 6.5x55 that I put togethere..one has a m38 barrel on it..23.5" and the other has the swede carbine barrel on it..about 16.75".... when I compare loads from rifle to rifle my hunting loads lose right at 200fps ...that figures out to roughly 30fps/ inch of barrel difference...both rifles do a great job on deer using the 129 and 140gr bullets...

I really don't notice a muzzleblast difference using that short barreled rifle...and truth is...it is one of my favorites..extra lite and extra short so it makes a great tree stand rifle....

Z

Bottle necked rifle cartridges generally loose 30 fps/inch in barrels 19" or longer. When you get shorter then 19", they loose 50 fps.

Straightwall and nearly straigthwall rifle and pistol rounds generally loose 30 fps/inch right on down to stub length.

Typical guns vary +/- 50 fps for the same chambering and barrel length.

This is a goofy suggestion maybe.

If you have a load you like and are going to stick with, I wonder if you would get an accurizing effect (a alBOSS) by fine-tuning the barrel harmonics. I mean, if you took a barrel facing tool and barrel crowning tool and took a little bit of metal off at a time (once you're in the ballpark for the right length), I wonder if you'd see groups tighten up, then get bigger, then tighten up in any sort of pattern as the amount of weight near the muzzle (barrel length) changes.

It might be fun to experiment along these lines with the current full-length barrel. You'll get practice facing and crowning (Maybe you don't need that. I advise from an inexperienced point of view), and you'll see whether there is much point in screwing around with it once you have it cut down to the desired length.

H. C.

quote:

---

This is a goofy suggestion maybe.

If you have a load you like and are going to stick with, I wonder if you would get an accurizing effect (a alBOSS) by fine-tuning the barrel harmonics. I mean, if you took a barrel facing tool and barrel crowning tool and took a little bit of metal off at a time (once you're in the ballpark for the right length), I wonder if you'd see groups tighten up, then get bigger, then tighten up in any sort of pattern as the amount of weight near the muzzle (barrel length) changes.

---

HenryC470, I seem to remember reading in a gun rag of some ilk back when the Boss first came out, that Browning came up with their idea because of events like you`ve described.
As I remember, they were haveing rifles returned with claims of bad accuracy and would lope a 1/4" or so off the barrel and recrown. The artical stated when they sent the rifles back no one noticed the "missing" lenght and accuracy was improved in most cases. They found a certain amount or lenght(?) of barrel removed gave the best result depending on cartridge while they were doing this. Finally one of the bright boys came up with the idea of the Boss to add or subtract wgt from the barrel. They gave the "best setting" in their instructions for each cartridge based on their results from prior barrel trimming lenghts.

Hey Joe,

Swartz Creek?

I used to live out your way.

H. C.

in the march 2005 issue of shooting times is an article by Rick Jamison addressing this very thing.

Using a 7mm RUM with a 32" barrel and 100-175 grain bullets the average was 3573 fps.

the same loads in the same barrel when trimmed to 28" averaged 3509 fps. or 16 fps per inch avg. loss.

when the barrel was then trimmed to 24" these same loads averaged 3332 fps. or roughly 60 fps per inch less than the 32" tube and 44 fps less than the 28" tube.

there was also an excellent article in rifleshooter magazine by Wayne VanZwoll in September/October 2003 that addressed this same question, but they took off one inch at a time with much the same results.

both articles mention that on some occasions an improvement in accuracy can be attributed to the shorter and inherently stiffer barrel.

hope this helps.