Why a 22 inch barrel on 7 rem mag from factory?

[Canhunter35]

I wouldn't call him wrong at all. He was speaking in generalities though. He was basically saying a 7mm started giving up too much with a shorter barrel and it wasn't worth shooting a short barrel 7RM vs a 270. That they wouldn't be enough difference in them to justify the added recoil and muzzle blast of the 7RM.

Here's a great case in point. Link below is to a Rifle Shooter article, where a guy actually cut the barrel off of a 7RM, 1 inch at a time and documented the results. They are interesting.

For test Load #1 he used factory Federal 7RM 150 gr SP ammo. By the time he got to 23" the 7RM 150 Gr bullet was only doing 2821 FPS. Federal states the velocity of their 270 Win 150 Gr SP ammo to be 2831 FPS. So..... In these tests a 23" 7RM barrel was really only running at 270 Win speeds.

I think, generally, it is considered a true assumption that a 7RM really doesn't start to shine and pay for itself until it gets to a 26" barrel. It is just handicapped some otherwise. So why handicap it? You are paying more money for brass, bullets, and powder, for not much gain at all.

Given the results below, I would never shoot a 7RM with a 22.5" barrel. That's just hurting your shoulder and wallet for nothing. My 7RM uses a 26" barrel and I wouldn't have it anyother way.

Link to the test and results:
https://rifleshooter.com/2015/04/7mm-remington-magnum-7-rem-mag-barrel-length-versus-velocity/

Good post. I agree. Maybe magnums don't need a long barrel but they deserve one. Otherwise shoot a standard cartridge. The only thing better than 26" is 28" lol

 

[graywolf]

That's an informative series of experiments ( Link to the test and results:
https://rifleshooter.com/2015/04/7mm-remington-magnum-7-rem-mag-barrel-length-versus-velocity/) with barrel chopping and it seems to be very well done. Interesting that he said he would build a 23" 7mm mag based on his data. To each his own, depends how you value weight/handling/velocity. I just threaded a Tikka 270 wsm for a suppressor and thought about cutting it from 24 to 22" but decided against it. I like the way it shoots too much to change it.

 

[Garycrow]

Here's a great case in point. Link below is to a Rifle Shooter article, where a guy actually cut the barrel off of a 7RM, 1 inch at a time and documented the results. They are interesting.

For test Load #1 he used factory Federal 7RM 150 gr SP ammo. By the time he got to 23" the 7RM 150 Gr bullet was only doing 2821 FPS. Federal states the velocity of their 270 Win 150 Gr SP ammo to be 2831 FPS. So..... In these tests a 23" 7RM barrel was really only running at 270 Win speeds.
...
Link to the test and results:
https://rifleshooter.com/2015/04/7mm-remington-magnum-7-rem-mag-barrel-length-versus-velocity/

Federal lists the muzzle velocity of that 150 gr. 7mm rem mag load at 3110 fps. They don't list the barrel length with that but for the sake of argument say it's 26". In the rifle shooter article the tester found that load shot 2939 fps at 26" so he's established that the factory ammo's actual velocity is 171 fps less than stated. If the federal load was rated at 3110 fps at 24" then the tester got 2881 at that length so the factory load is 229 fps less than claimed. Now you want to compare it to federal's 270 win load but you assume the 270 is going to clock at the full claimed speed? If you want to compare apples to apples then you need to correct the 270's velocity by the same amount so 2831-171=2660 fps. Now is a 7mm rem mag shooting 150 grainers at 2939 the equivalent of a 270 shooting 150 grainers at 2660 fps?

The first mistake the tester made was by using factory loads that don't chronograph what the maker claims. This is not unusual for the 7mm rem mag, it's notoriously underloaded by the factories because back in the '60's when it first came out remington found some pressure spikes they couldn't explain with the initial testing so they downloaded it, a practice that's been kept since then and also carried over to the loading data. Notice that the SAAMI limit is 61000 psi for the 7mm rem mag while it's 64000 psi for most other belted magnums, that's to allow for the pressure variations they experienced 50 years ago in testing. Today's powders and bullets weren't available back then so more than likely those pressure swings wouldn't be present if they repeated the certification tests today but since it was certified at 61000 psi that's where the limit for factory ammo and handload "book" recipes stands. If you want to make a real comparison to a 270 then you need to use ammo that actually chronographs the velocity it's claimed, not factory ammo that's 171 (or 229) fps less than claimed.

Enough beating a dead horse. Suffice it to say the 7mm rem mag isn't a 270 when loaded to it's potential. My own 24" 7mm rem mag go to load is a 145 gr. Barnes LRX at a chronographed 3225 fps. By the tester's findings he lost an average of 28.3 fps per inch so if I had a 26" barrel I'd likely get 3282 fps, and if it were the length of the Tikka at 22.6" I'd get 3185 fps so going from a 26" barrel to a 22.6" barrel I'd lose a whopping 97 fps. That's nothing in the real world and it's not worth it to me to put up with carrying the longer barrel around. On a range queen it doesn't matter but for a hunting rifle the trade off of a few fps lost for a handier rifle is well worth it to me.

 

[Barrelnut]

Federal lists the muzzle velocity of that 150 gr. 7mm rem mag load at 3110 fps. They don't list the barrel length with that but for the sake of argument say it's 26". In the rifle shooter article the tester found that load shot 2939 fps at 26" so he's established that the factory ammo's actual velocity is 171 fps less than stated. If the federal load was rated at 3110 fps at 24" then the tester got 2881 at that length so the factory load is 229 fps less than claimed. Now you want to compare it to federal's 270 win load but you assume the 270 is going to clock at the full claimed speed? If you want to compare apples to apples then you need to correct the 270's velocity by the same amount so 2831-171=2660 fps. Now is a 7mm rem mag shooting 150 grainers at 2939 the equivalent of a 270 shooting 150 grainers at 2660 fps?

The first mistake the tester made was by using factory loads that don't chronograph what the maker claims. This is not unusual for the 7mm rem mag, it's notoriously underloaded by the factories because back in the '60's when it first came out remington found some pressure spikes they couldn't explain with the initial testing so they downloaded it, a practice that's been kept since then and also carried over to the loading data. Notice that the SAAMI limit is 61000 psi for the 7mm rem mag while it's 64000 psi for most other belted magnums, that's to allow for the pressure variations they experienced 50 years ago in testing. Today's powders and bullets weren't available back then so more than likely those pressure swings wouldn't be present if they repeated the certification tests today but since it was certified at 61000 psi that's where the limit for factory ammo and handload "book" recipes stands. If you want to make a real comparison to a 270 then you need to use ammo that actually chronographs the velocity it's claimed, not factory ammo that's 171 (or 229) fps less than claimed.

Enough beating a dead horse. Suffice it to say the 7mm rem mag isn't a 270 when loaded to it's potential. My own 24" 7mm rem mag go to load is a 145 gr. Barnes LRX at a chronographed 3225 fps. By the tester's findings he lost an average of 28.3 fps per inch so if I had a 26" barrel I'd likely get 3282 fps, and if it were the length of the Tikka at 22.6" I'd get 3185 fps so going from a 26" barrel to a 22.6" barrel I'd lose a whopping 97 fps. That's nothing in the real world and it's not worth it to me to put up with carrying the longer barrel around. On a range queen it doesn't matter but for a hunting rifle the trade off of a few fps lost for a handier rifle is well worth it to me.

I agree that it's all going to vary from barrel to barrel and load to load and lot to lot. It just so happened that the tester used factory 7rm 150 Gr. ammo and there just happens to be a factory 150 gr. load for the 270 Win. I don't know why his 7rm factory ammo was slower that what Federal said, but I suspect he just had a slow barrel. Federal ammo can vary quite a bit too. I seen some surprisingly large difference from loads within the same box!

I did take a look at the NOSLER book load data: for the 270 Win 150 Gr. max velocity spreads were from 2782 FPS to 2913 FPS and for the 7RM 150 Gr loads had max velocity spreads from 2968 FPS to 3248 FPS. So everybodys results will vary some depending on the load. But fact is a 7RM is kinda overbore and it doesn't perform well with shorter barrels.

Also note that the tester mentions the fact that the 7RM got more obnoxious to shoot at 23". Quote: (At 23″ in barrel length the rifle became noticeably louder. The 20″ barrel was unpleasant to shoot, the 165 grain GameKing load became very smokey, and the 175 grain GameKing load exhibited a lot of flash (I wrote "flash!!!" in my notes). End Quote:

Maybe a short barrel 7RM would perform more like a 280 or 280AI. But you could probably get a standard cartridge to easily perform as well (and with less recoil, muzzle flash, and cost) as a short barrel 7RM.

A 270, 300, or 7 WSM would be a better choice if a short barrel was the main consideration. They would do better because they work well with faster powders and are more efficient with it. I use a 300 WSM with a 24" barrel as more of a "woods" gun for elk and such.

 

[graywolf]

A 270, 300, or 7 WSM would be a better choice if a short barrel was the main consideration. They would do better because they work well with faster powders and are more efficient with it. I use a 300 WSM with a 24" barrel as more of a "woods" gun for elk and such.

What do you think a good faster powder for a short 20-22" barrel WSM would be? Or did you mean by "short" a 24" barrel? I'm using RL26 with a 130 gr and getting 3400 fps easily with my 24" Tikka factory barrel .

 

[Rich Coyle]

I bet the powder that produces the fastest velocity in a short barrel is the same powder that produces the fastest velocity in a long barrel. Anyone with confirming or correcting documentation?

 

[Bigeclipse]

Most manufacturers do some really stupid things that make no sense to most people, and the rifles they build fit one preferred group, or the other, but rarely does a rifle fit all of the desired characteristics that allow the hunter & shooter the fit, form, and function that would allow the rifle to be used in any/every way possible for all customers to be 100% satisfied. Actually 26-30" takes the best advantage of the cartridge. But 26" for hunting works best, as it's the best compromise of velocity and maneuverability.

Agree and Disagree. While having a short barreled 7mm rem mag really makes no sense, gun manufacturers are not stupid. They are not in the game to make really good rifles for the sake of making really good rifles. They are in the game for one reason...and that is money. I would say 90% of hunters out there do not care about how fast there rifle is truly firing. All they care about is, give me the cartridge I want in the lightest weight rifle I can get to hunt and kill deer at 300 yards or less. They then go grab a box of ammo that has the best claims of speed and "killing power". They then go out and shoot their deer. I think it makes total sense for Tikka to make their rifle in 22in. Many buy the Tikka t3 for 2 reasons...the accuracy claim in a lightweight rifle and that is exactly what Tikka does. They probably could have got away with 24in and still been light weight. I know out of all the people I hunt with, I am literally the only one that cares about these details. The rest of my group just wants the caliber they have trusted for years in a cool new gun and that is it.

 

[machoking]

But the barrel is actually 24". It's a misprint. No need to go over it ad nauseum when it's a misprint.

 

[Barrelnut]

I agree that it may just be a misprint on the Tikka specs pages. If you already have it, measure with a cleaning rod down the muzzle until it hits the bolt face and see what it's got.

Jack O'Connor is famous for saying that if you shoot a 7RM in anything shorter than a 26" barrel, you might as well be shooting a 270 Winchester, cause the performance level would be about the same.

Oops misquoted.
From the 1978 edition of The hunters Shooting Guide: Jack actually said, "Shoot a 7mm cartridge in a 22-inch barrel and any difference in velocity between it and the 270 is peanuts."

But as said, the barrel length is probably just a misprint, but if it's not, I think the OP should consider Jacks words and look for something with a longer barrel.

Good Luck

 

[machoking]

That was also a time when the ballistics of the 7mm lineup weren't what they are today. A 162 grain ELD-X makes all .270 bullets except the 170 EOL look pretty chumpy.

 

[MudRunner2005]

I'd look into the Browning Hells Canyon Speed Long Range in 7mmRM... Comes with a 26" magnum sporter fluted barrel with a 1:8 twist. Right out of the box, it's ready to shoot Berger 195's.

 

[Tnwhip]

Putting a short barrel on a magnum is like putting a 2 barrel carburetor on a 427! That is the same thing they did with the 22 Nosler for the AR 15. They came out with a 18" It needs a 24" to get close to a 22-250.