I have a barrel I suspect is slow and as soon as another source of brass is available I'll know for sure but it has me thinking. What makes a barrel slow ? Do some makers and methods make slower barrels generally ? What makes for a fast barrel ? My Benchmark barrel seems to have accuracy potential but I'm consistently 3-4 grains less than what others report at max pressure by brass signs and 100-150 fps less than most report. This isn't just less than internet bullchitters but less than friends with the same round and usually shorter barrels. I'm soon going to pull the barrel and have a very expensive tomato stake and I don want to repeat this ever again.
Slow barrels and slow barrel makers
- Thread starter Shrek
- Start date
Dave,
There are a bunch of different things that can led to slower speeds.
Different lots of powder can have up to 80fps difference
Different freebore than your buddies guns.
Different barrel twist rates
Are you running the same kind of powder as your friends?
If the barrel shoots well I really wouldn't worry about the speed all that much, unless you need it to reach a certain distance. I have had 5 .284 barrels from 4 different makers and all of them have been very close on velocity.
KT
There are a bunch of different things that can led to slower speeds.
Different lots of powder can have up to 80fps difference
Different freebore than your buddies guns.
Different barrel twist rates
Are you running the same kind of powder as your friends?
If the barrel shoots well I really wouldn't worry about the speed all that much, unless you need it to reach a certain distance. I have had 5 .284 barrels from 4 different makers and all of them have been very close on velocity.
KT
Jay Christopherson
Not An Admin
dkhunt14 said:
+1 to all three of Matt's statements. Particularly the first, which I think a lot of people overlook.
I've got more freebore , longer barrel , and I've tried H1000 , rl26 , and Retumbo. Retumbo is the best performing so far but still a disappointment. II'm Pretty sure the Norma brass has something to do with it but I'm not really trying to find the cure for this barrel or just accept it. I'm wanting to talk about what makes for a slow or fast barrel not the chamber or any particular barrel. It's the differences in the barrels themselves I want to learn about. Cut of pull rifled , types of rifling , rates of twist ? What makes the barrel itself fast or slow.
STOMP442
Gold $$ Contributor
I think it just happens, you can have barrels roll off the press one after the other and they more than likely will have totally different personalities. One will shoot a certain powder and bullet combo great while the other may perform totally lack luster with that same combo. A slow hit is better than a fast miss every time.
It would be nice to know more details. What cartridge, what bullet and how much freebore. I believe they just vary and also what powder and bullet they want to shoot. I had a Krieger 8 twist Dasher that could only shoot 2900 tops. Most others will make 3000 with the same reamer. It just varies. Matt
The particulars of the chamber are it's a 6.5 RSAUM .298 nk and .178 freebore 26" 8 twist Benchmark barrel. Best I could do with 142gr matrix and H1000 was 2970 fps over 57.grs of powder. I'm currently working on 150gr Matrix and Retumbo and I'm going to be in the same velocity range I think when I'm done working them up. Actually , if my 7mm wsm gets here before I finish and it shoots well the barrel is coming off the 6.5 RSAUM. I don't know at that point if I want to try a different barrel in 6.5 RSAUM or a 6.5 WSM. It's why I want to know the why , what , and who makes fast and accurate barrels. I'm about done playing with this benchmark barrel.
+ 1 on what Stomp said.STOMP442 said:
I know some who buy barrels in pairs hoping that twin barrels can share loads. More often than not, they have totally different personalities. I have a few benchmarks as do some friends and I know a friend has a slow one, but mine are running similar loads to most other barrels.
On top of this, the last really fast barrel I had was a 7mm 9" twist Broughton. I could really load this one up fast and it went great for ages. After a lot of good use, I got 2" cut off and rechambered and now it s the slowest barrel I have ever had. I have to run lighter than usual loads or build too much pressure.
As has been mentioned, many barrels do pick up speed after 150 rounds or so, but I have only had them climb 50-80 fps, never 150 fps.
To be more clear on my desire for velocity I'm hunting with this rifle not match shooting. It's a backpack mountain hunting rifle so to save weight I mounted a Swarovski with the BT turret which only has 10.5 moa elevation stop to stop. I want the velocity to put energy down range and extend the distance I can dial within the scopes limitations.
If you are after speed Try a different powder. Larry
QL with a 142 Sierra and 57GR H1000 26'' barrel Give the speed of 2817 - 2970 is fast not slow. LarryDaveinjax said:
Dave,
If you can I would try to get your hands on some Remington brass for a test. Supposedly thinner walled brass and handles pressure a little better than Norma brass. Most people seem to be in the 60 to 61.5 range with 140 grn. bullets. Start low and work your way up or not. This is for H1000 powder. Good luck and keep us posted.
Regards, Paul
www.boltfluting.com
If you can I would try to get your hands on some Remington brass for a test. Supposedly thinner walled brass and handles pressure a little better than Norma brass. Most people seem to be in the 60 to 61.5 range with 140 grn. bullets. Start low and work your way up or not. This is for H1000 powder. Good luck and keep us posted.
Regards, Paul
www.boltfluting.com
I'm not exactly sure of the round count but between 250 and 300 now. Maybe I have too high of expectations. I'm out of the 142 matrix so I can't run them with either the Retumbo or the rl26 which I think would help them. I'm running Norma 7mm saum necked down and it doesn't take much to get extractor marks and slightly heavy bolt lift but the cci 200 and cci 250 primers don't look bad to me. Edges still have a touch of roundness and haven't flattened completely. I have a little bit to go with the Retumbo and I picked up some rl33 to try behind the 150's.
I didn't mean to get so far into this particular rifle but more to finding fast and accurate barrels.
I wish I had quickload to play on but I don't even have a computer anymore. I do everything on a wireless tablet or my smartphone.
I didn't mean to get so far into this particular rifle but more to finding fast and accurate barrels.
I wish I had quickload to play on but I don't even have a computer anymore. I do everything on a wireless tablet or my smartphone.
Boltflutter , the 60-61.5 and 3050-3100 is where everyone I know is running and exceptional rifles are running well above 3100. It's why I was saying I'm 3-4 grains below and 100-150 fps slow. I'm trying to wait for some of the GAP 4S brass or Remington brass to come available. They're all running Remington brass.
Toolbreaker
Gold $$ Contributor
With complete disregard to accuracy, the speed differences before reaching excessive pressure could be attributed to several items within the barrel itself. Just thinking out loud:
-bore diameter
-rifling diameter
-rifling width and geometry (5R, ect)
-consistency of rifling width
-whether the bore chokes at the muzzle, or is consistent throughout the barrel length
-surface finish of bore & rifling
-how straight the bore is throughout the length of the barrel
-half a dozen other things that I can't think of
This is just my speculations only. Several other things should be at play also, such as differences in bullet jacket alloy, varying bullet bearing lengths, different amounts of fouling, ect.
-bore diameter
-rifling diameter
-rifling width and geometry (5R, ect)
-consistency of rifling width
-whether the bore chokes at the muzzle, or is consistent throughout the barrel length
-surface finish of bore & rifling
-how straight the bore is throughout the length of the barrel
-half a dozen other things that I can't think of
This is just my speculations only. Several other things should be at play also, such as differences in bullet jacket alloy, varying bullet bearing lengths, different amounts of fouling, ect.
BoydAllen
Gold $$ Contributor
A friend casts laps for all of his barrels, before he does any machining, as a way of measuring their groove diameters and being able to feel loose and tight spots. It sounds to me like you may have a barrel that is a little on the tight side. If you know someone who is expert in slugging barrels, or casting a lap to do the same thing, you might try taking a look at your barrel through that lens. I have friends who shoot WSMs and while Winchester brass may not be as good for body thickness runout, it is a lot more tough, and handles pressure better than Norma typically does. For hunting they have gotten very good results. I am not much of a fan of Remington brass. but then I have not shot it for a number of years.
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