Affect of Barrel Length & Accuracy

[gsg5pk]

Reloading tune for Different Barrel Lenght

My best load for current rifle (24" Barrel 1:10" tw) was 175 LRBT @ 2,650 fps with SD 6.9


But today I try my load with a new rifle which just chamber a new barrel by Gun Smith and found that this load was not accuracy in this rifle. (New Barrel was Bartlein 5R 30" with 1:10" tw , chamber with the same spec as my previous rifle)

So, the factor was depend on the longer barrel will give the higher MV which may out of accuracy node?



Because I test my friend rifle (24" barrel 1:10" tw) also accuracy with my load.


Is it possible that the longer barrel will affect SD and ES?


Haven't measure yet due to forgot to bring the chrono to the shooting range.

 

[LCazador]

No two rifles are alike , and for that matter no two barrels are alike ! Yeah you will have to find a new load for your new barrel . Is that barrel broken in yet ? Are you using new brass and has it been fireformed in your new barrel ?

 

[Jayman_10x]

It's a well worn principal that no two barrels are alike. Whether lengths are same or not is immaterial.

 

[Shynloco]

You might have already considered this, but I wouldn't be concerned about any of that at this point, until you get a few hundred rounds down the tube, no matter the barrel or who made it. I certainly agree with the other posts, but the evaluation you seek should have the basics in a comparison. Just a consideration I'd be looking at.

 

[Erik Cortina]

You might have already considered this, but I wouldn't be concerned about any of that at this point, until you get a few hundred rounds down the tube, no matter the barrel or who made it. I certainly agree with the other posts, but the evaluation you seek should have the basics in a comparison. Just a consideration I'd be looking at.

Concerned about any of what?
Why does he need to put "a few hundred rounds down the tube"?

Please elaborate.

 

[gsg5pk]

My testing was record after break-in the new barrel.


Every factor remain the same by using new brass + Sizing with FL nk sizing die.
Test at 200 yards.



The best group of this new barrel was by 168 SMK (5 shots Around .25 MOA) but when test my accuracy load (of previous 24" rifle) with 175 LRBT was 5 shots around .5 MOA

 

[Keith Glasscock]

No doubt,

New barrel, New chamber dimensions, or New length makes the tune spot move dramatically. Sounds like you have a good barrel, it just needs to get tuned.

 

[bheadboy]

+6 in bbl length, different brass, different chamber, different bbl inside dimensions, harmonic vibrations at a different point in length,

work up loads as has been said, it is not the same rifle.

Bob

 

[gsg5pk]

My current rifle with 24" barrel was shooting accuracy enough for competition.


But I'm looking for the secondary rifle with longer barrel for shoot 800 - 1000 yards. Expected to get 185 LRBT @ 2,700 - 2,800 fps out of those 30" barrel. Because I only get 2,590 fps out of 24" barrel.



In case that the theory about different rifle prefer different load, then how to prepare ammo for competition? I firstly plan to share the same load and keep one for secondary rifle. But if both can't share the same load, I have to work double?

Even, both barrel are chamber with the same reamer & also same gun smith? (Both barrel current and new barrel are Bartlein 5T with 1:10 tw and same contour. Only different in finish length)

 

[Shynloco]

You might have already considered this, but I wouldn't be concerned about any of that at this point, until you get a few hundred rounds down the tube, no matter the barrel or who made it. I certainly agree with the other posts, but the evaluation you seek should have the basics in a comparison. Just a consideration I'd be looking at.

Concerned about any of what?
Why does he need to put "a few hundred rounds down the tube"?

Erik,
Based upon MY experiences and readings, there are two schools of thought on new barrels and putting rounds down them to "season" them. Apparently you must belong to one school of thought and I the other. In MY experiences of having Shilen, Hart and Kreiger barrels put on some of my rifles, I've found they perform better with time, AFTER they've had 200 or so rounds put down them. As for "concerns", I want to give MY barrels time to "season" before I fully evaluate their performance and seek best accuracy from them. I am well aware of that some folks believe those evauluation begin with round #1. I am not one of those people and hence my comments which was MY opinion which I stand behind just as you do yours. Hope that clarifies my comments which you may or may not agree with.

Alex

 

[Turbulent Turtle]

Reloading tune for Different Barrel Lenght

My best load for current rifle (24" Barrel 1:10" tw) was 175 LRBT @ 2,650 fps with SD 6.9


But today I try my load with a new rifle which just chamber a new barrel by Gun Smith and found that this load was not accuracy in this rifle. (New Barrel was Bartlein 5R 30" with 1:10" tw , chamber with the same spec as my previous rifle)

So, the factor was depend on the longer barrel will give the higher MV which may out of accuracy node?



Because I test my friend rifle (24" barrel 1:10" tw) also accuracy with my load.


Is it possible that the longer barrel will affect SD and ES?


Haven't measure yet due to forgot to bring the chrono to the shooting range.

In theory, the accuracy node is dependent on barrel dwell time and barrel length. You have just changed both by adding 6 inches to the barrel. The longer barrel should have larger accuracy nodes so finding one should be fairly straightforward.

 

[BoydAllen]

Bottom line...forget the other barrel completely and do a load work up from scratch. One thing you might retain for starters, if the chambers were cut with similar reamers is the seating depth that you use to start your testing (if you are using the same bullet for both). I can find a load for a particular powder and bullet pretty quickly, with one trip to the range (or disqualify that combination) if the rifle and barrel do not have any issues. The trick is to have a method that makes sense, so that you are not simply casting about.

 

[Erik Cortina]

Shynloco, I guess I just don't have enough barrel life on my guns to let the barrels "season". However, they have all shot great for me so far from the first round.

 

[bigedp51]

Its my understanding that bozo699 rubs Viagra on his barrels, have you tried this yet?



Remember if your barrel remains stiff for over four hours don't call a gunsmith. (or a Doctor)

 

[gsg5pk]

The guideline of Berger show these range for Varget

(Out of 24" Barrel)

38.5 gr. @ 2,361 fps. to 43.0 gr. @ 2,615 fps.


And my accuracy load also lower number in SD , ES for my current 24" barrel was 43.5 gr. @ 2,648 fps. , SD 6.9 , ES 9 (test 5 shots)



So, what is the expected MV when a given factor of increase barrel length from 24" to 30" - 32" ?

In case of finding a new load for 30" barrel, these sample would be enough for the first test?

40.0
40.5
41.5
42.0
42.5
43.0
43.5
44.0
44.5

Totally 50 Rounds


I'm looking for high MV node for shooting FTR 600 and 800 yards.

 

[Steve Blair]

Its my understanding that bozo699 rubs Viagra on his barrels, have you tried this yet?
Remember if your barrel remains stiff for over four hours don't call a gunsmith. (or a Doctor)

[br]
+1 for Viagra barrel conditioning. It will definitely increase rigidity. Make sure that your barrel has adequate radial clearance. The diameter will also increase.

 

[jsthntn247]

I would run a ladder at 300 or more yards with . 42-45.5 in .3 grain increments. You should be able to find 2 good nodes in there. Ocw test with the node groups then play with seating depth. Total load development shouldn't take more than 50 rounds.

 

[Down South]

Shynloco, I guess I just don't have enough barrel life on my guns to let the barrels "season". However, they have all shot great for me so far from the first round.

+1


According to what i read in Tony Boyer's book if i remember correctly, he doesn't shoot a major competition with a barrel with more than about 50 rounds on it. If thats true he dang sure aint letting it "season"........lol.......He claims a barrel starts going downhill after the 1st shot.......My guns have always shot great from jump street. With my current FTR rig, I picked up the gun on a friday after being built, did load developement Saturday and Sunday, shot a 600 yard match the following weekend with a high master score so i guess i just don't go along with the seasoning theory.

 

[bbarber25]

Its my understanding that bozo699 rubs Viagra on his barrels, have you tried this yet?



Remember if your barrel remains stiff for over four hours don't call a gunsmith. (or a Doctor)

I don't care who you are that's funny right there!