Barrel lenght vs velocisty
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williamwjohnson
New member
From everything I have read it starts dropping off after 24". Should be okay.
specializedcc
New member
From what Ive read its supposed to be 100fps for every inch of barrel length.
Blackhawk43
New member
I can remember reading it but I don't remember where. It seems like it was between 35 and 50 fps per inch depending on the velocity of the cartridge, faster cartridges lost more per inch.If I remember correctly 3400 to 3600 lost about 50 fps. I wish I could be more help but I think of all the things I have lost over the years I will miss my memory the most.
gotchanow
Active member
the velocity loss depends on alot of variables including the individual barrel, powder burn rate, and how efficient the case is. I would say the 30 to 60 fps is a good guess but without trying it you wont know for sure. Ive shortened alot of barrels and have never yet seen a full 100 fps drop for an inch of barrel. In fact my 375 ruger only had 60 fps drop when I cut it from a 24" to a 22" barrel.
OldTurtle
Moderator - Deceased
This is from an article in the Shooting Times:
Quote:
The first cut is the deepest
Barrel reduction was actually easy, if initially a little scary: the RPAs shot groups of less than 0.5in - from the off taking a hacksaw blade to barrels of that quality and accuracy was a little difficult, believe me. Means must, however, and I had soon measured out inch increments in order to aid cutting, with the barrel supported in a Ken Farrel barrel vice.
As I mentioned, it was only velocity reduction, not accuracy, that was being recorded, so a simple deburring of the sensitive muzzle and crown areas was undertaken between each cut. To measure the muzzle velocity of each calibre as the test progressed, a five-shot string was recorded over a chronograph for every inch of barrel reduction.
You will immediately see the correlation between the predicted computer-generated data and the real-world experiment. Taking into account the vast variances of the differing barrel makes and their internal dimensions, the results were really good and, to my mind, highly valid.
Conclusions
Take the .223 calibre test first: 3,402fps velocity from a 24in barrel is a good starting point a good varmint/fox load and also, for Scotland, a legal roe deer load, generating 1,337ft/lb energy. Reducing the barrel, inch by inch, to 20in only loses 149fps, very little in practical terms, yet it brings real benefits as far as weight reduction and overall length are concerned. Taking an extra 2in off results in an exceedingly 'trim' rifle, though you do start to notice an increase in muzzle blast.
At 18in, the 3,185 fps velocity and 1,171ft/lb energy is only 217fps short of the initial velocity - so what does that mean to a fox shooter or stalker of Scottish roe?
Well, zeroed at 100 yards with the starting velocity, you are -2.1in low at 200 yards and -9.5in low at 300 yards. No problems there, but what about with the shorter 18in barrel?
A reduction of 217fps equates to a zero of 100 yards, a drop of -2.5in at 200 yards and -11.3in at 300 yards. At 200 yards, therefore, there is only a -0.4in difference, and at 300 yards only a -1.8 difference.
"Gains in terms of weight and length reduction far outweigh the minuscule velocity loss."
Hope this helps a little...
Quote:
The first cut is the deepest
Barrel reduction was actually easy, if initially a little scary: the RPAs shot groups of less than 0.5in - from the off taking a hacksaw blade to barrels of that quality and accuracy was a little difficult, believe me. Means must, however, and I had soon measured out inch increments in order to aid cutting, with the barrel supported in a Ken Farrel barrel vice.
As I mentioned, it was only velocity reduction, not accuracy, that was being recorded, so a simple deburring of the sensitive muzzle and crown areas was undertaken between each cut. To measure the muzzle velocity of each calibre as the test progressed, a five-shot string was recorded over a chronograph for every inch of barrel reduction.
You will immediately see the correlation between the predicted computer-generated data and the real-world experiment. Taking into account the vast variances of the differing barrel makes and their internal dimensions, the results were really good and, to my mind, highly valid.
Conclusions
Take the .223 calibre test first: 3,402fps velocity from a 24in barrel is a good starting point a good varmint/fox load and also, for Scotland, a legal roe deer load, generating 1,337ft/lb energy. Reducing the barrel, inch by inch, to 20in only loses 149fps, very little in practical terms, yet it brings real benefits as far as weight reduction and overall length are concerned. Taking an extra 2in off results in an exceedingly 'trim' rifle, though you do start to notice an increase in muzzle blast.
At 18in, the 3,185 fps velocity and 1,171ft/lb energy is only 217fps short of the initial velocity - so what does that mean to a fox shooter or stalker of Scottish roe?
Well, zeroed at 100 yards with the starting velocity, you are -2.1in low at 200 yards and -9.5in low at 300 yards. No problems there, but what about with the shorter 18in barrel?
A reduction of 217fps equates to a zero of 100 yards, a drop of -2.5in at 200 yards and -11.3in at 300 yards. At 200 yards, therefore, there is only a -0.4in difference, and at 300 yards only a -1.8 difference.
"Gains in terms of weight and length reduction far outweigh the minuscule velocity loss."
Hope this helps a little...
