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Old July 14, 2011, 09:17 PM   #1
jimbob86
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Short barrel velocities?

Anybody reload 7-08 for a 16.5 barrel?

I just picked up a Ruger Frontier in 7-08 ...... wondering what kind of velocity you get out of that short barrel.
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Old July 14, 2011, 10:57 PM   #2
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Velocity for Short Barrels

A typical reload that gets 2835 ft/sec with a 139 gr bullet out of a 24" barrel will get about 2640 ft/sec from a 16.5" barrel.

http://shootersnotes.com/calculator/velocity-estimator/

You can also find loads for the 7mm - 08 at http://ammoguide.com/?catid=15 and calculate the velocity for the new barrel length by selecting the "velocity estimator" button above the load details.
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Old July 15, 2011, 08:03 AM   #3
Brian Pfleuger
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I load 7-08 in a 15" Encore. I use the 110gr Barnes TTSX for deer. I get 2835fps with that. I got around 2600 with factory Remington 140gr CoreLokt ammo.
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Old July 15, 2011, 08:34 AM   #4
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Thanks!

Quote:
I got around 2600 with factory Remington 140gr CoreLokt ammo.
More than acceptable.

I was looking to load 145 or 160 grain Speer boat tails to 30/30 velocities ...... looks like that will be easy- might even have to reduce the charge or use a quicker powder.......... the top powders listed in the Speer #13 manual are pretty slow- W760, Re19, H414, and the various 4350's,and 4831's ...... powders that have worked well for my .270 with 130 gr bullets..... I did a bit of poking about on the net and read where IMR 4064 gave slightly slightly lower velocities than one of the above powders, but with less flash and bang ........ I'll probably try that, as well as the slower ones that I have already.

Next question: How different in performance, in your experience, are W760 and H414?
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Old July 15, 2011, 09:13 AM   #5
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Quote:
Next question: How different in performance, in your experience, are W760 and H414?
W760 and H414 are right next to each other on the Hodgdon Burn Rate chart at 108 and 109 respectively. They're both spherical powders with similar uses and burn at very close rates. If you go to the Hodgdon Reloading Data center, and look at .30-06 loads, they list identical charges at identical velocities with identical pressures.

I can't tell you they're the same powder, but this wouldn't be the first time that Hodgdon sold one powder under two different labels.
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Old July 15, 2011, 09:50 AM   #6
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that's exactly what they are doing !
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Old July 15, 2011, 09:05 PM   #7
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Ok..... anybody know what height ruger rings I need?

Scope is a Leupold 2.5x28 IER.
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Old July 16, 2011, 08:04 AM   #8
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I just picked up an Encore 15" barrel in 7mm-08. I worked up a load in Quickload using a 139grn Hornady SP and RL-17. I don't have the charge weight or theoretical velocity written down in front of me but that seemed to work out to be a good combination. My order of 7mm-08 and .284 bullets should be here in less than a week.
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Old July 16, 2011, 09:45 AM   #9
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One thing to realize with a short barrel is that attempts to maximize velocity are likely to dramatically increase recoil. More velocity means maintaining pressure behind the bullet. More pressure equals more muzzle pressure, more muzzle pressure means more recoil, sometimes dramatically. These short barrels can easily be in the realm of 15,000psi muzzle pressure. The "rocket effect" is considerable with those pressures. This is an area where QuickLoad shines. You can find safe loads, sort them by muzzle pressure and find the highest speeds with the lowest pressure/recoil.

This is not to say that recoil is in any way unbearable with a short barreled 7-08. I can shoot all day even with full-power factory loads. The muzzle blast is substantial though. Plugs and muffs together is advised, for max loads especially.
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Old July 16, 2011, 11:42 AM   #10
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Since I also have a short barreled rifle (Ruger 260 with 16.5 inch barrel), I've been quite interested in this discussion, but nobody has answered the question that I have, so I'll ask it. In a short barreled rifle, it seems logical to me that the best (most efficient) powder would be one of the faster powders for that caliber. Is that correct? The load I use is about midways between min and max (38.5 gr of IMR4064, behind 120 gr Nosler BT), and is quite accurate, but not what you'd call a hot load at all. I'd like a hotter load, but that bullet with that powder, as I approach maximum, gets considerably less accurate. Would a slower powder in that short barrel get me a significantly faster muzzle velocity? I don't have Quickload and I don't have a chronograph, so I can't answer the question on my own.
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Old July 16, 2011, 07:55 PM   #11
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Powder Choices for Short Barrels

One of the neat things about QuickLoad is that you can get plots of pressure and velocity along the barrel. The velocity is highest when the pressure rises quickly and stays high for as long as possible. Start by looking at those plots for a few loads with powders of different burn rates.

You can then get some insight into muzzle pressure and velocity optimizations by looking at different powders and tracking the muzzle velocity and pressure.

I did this for a correspondent awhile back with the .223 Remington. I learned that it is indeed possible to get modest velocities with low muzzle pressures using fast burning powders.

It also appears that QuickLoad can help you select a handful of powder that give getter velocities in your short barrel than would be the case for loads optimized for standard-length barrels.

The flip side is that these better velocities come with the price of higher muzzle pressure. The backblast will be even more significant if you're sing a muzzle brake so be sure to wear plugs and muffs!
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Old July 16, 2011, 08:05 PM   #12
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603 , I have been reloading under that same assumption myself for many years . Is it a fact that you regain some velocity by using powders with a faster burn rate ? One thing is for sure , it really cuts down on the fireball that exits the muzzle . As I understand it , that fire ball is Powder burning outside of the barrel . Ergo my thinking is Faster Powder burns more completely thus having a better chance of obtaining top velocity for that Barrel length ! Of course my thinking can be flawed occasionaly !
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Old July 16, 2011, 09:22 PM   #13
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re: recoil

As "Deer gun for a 10 year old boy " is the object of the excercise ....... I'm not planning on seeing how fast I can launch bullets.....

I don't have Quickload, but based on my experiences with another short barreled firearm, I'm planning on trying a Speer 160 BTSP (Speer #1634) over a start load of 34 grains of IMR 4064 increasing the charge until I can get to 2400 f/sec....... if that's too much recoil for the sprog (he likes full house .357), I'll drop down to the 145 gr , again with a 2400 f/sec target velocity.

If I had an extra 800-1000 bucks, I'd get a can on the thing, too! ...... but I don't .....
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Old July 17, 2011, 11:20 AM   #14
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oneoldsap, I should probably get a chronograph and buy a few more powders and just find out once and for all what gets me the most velocity. And Quickload would be nice to have. But, I'll probably just stick with the loads I have. If higher bullet velocity was that important to me, I'd just put money into a 20 inch barrel (not 22 and not 24) and go from there. If I really have to reach out and touch, my Sako 270 does an excellent job for as far out as I ever did and probably ever will shoot a deer (450). I'll just use the stumpy barreled 260 for the 'small' pasture.
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Old July 17, 2011, 11:58 AM   #15
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I'll ask again..... help plz?!?

Thanks for the input on the short barrel volocities, but I have another problem:

Quote:
Ok..... anybody know what height ruger rings I need?

Scope is a Leupold 2.5x28 IER.
A bit of poking around at Ruger tells me that:

The Ruger 77 Mk II needs rings of different heights (a taller front ring) when mounting a scope on the receiver conventionally.

The Ruger #1 does not. I has a similar (the same?) "quarter rib" over it's reciever that the Frontier has over it's barrel. I want to put the scope on the rib. Ruger has a rail adapter that allows the use of weaver style rings, but I'd rather not buy that, too, and add any unnecessary height to the equation.

The Frontier is a version of the 77 Mk II.

Same height rings? Or the set with the front ring taller? What height with the IER scope? (Low, extra-Low?)

Thanks,

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Old July 17, 2011, 12:45 PM   #16
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That's interesting.... My .204 is an M77 MkII and it uses conventional rings....
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Old July 17, 2011, 06:45 PM   #17
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Ruger's website sez so, but is not clear on the rings necessary for forward mounting....... The also have an adapter to put a a pic-rail atop the rib, but I am not looking to add any unnecessary height.

Anybody in the GreatHiveMind know? .......or I could just call them tomorrow morning........
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Old July 17, 2011, 08:12 PM   #18
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In my Ruger Compact in 260, I lose 192fps, pushing 120s to 2660.
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Old July 18, 2011, 10:03 AM   #19
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@Geauxtide, thanks for that info. You didn't say what powder you used and if the load was near max, but the 200 fps velocity loss is useful info to me.
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Old July 18, 2011, 10:16 PM   #20
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Jimbo,

If you look at the Ruger Scout, that rail appears to be uniform height above the bore and appears to me to clear line of sight across the top of the receiver, so you'd want the same rings front and back. I just don't have one to know for sure. I do have that same scope on my Steyr JC Scout, and it's about 1.366" (34.7 mm) diameter front and back. You would think identical low rings front and back would be fine, therefore. They just need their center heights to exceed 0.683" above the rail.

But rather than guess, I suggest you call Ruger to get the straight poop. Their chart doesn't provide center height.

Re powder: Bullet velocity depends on the average pressure at its base during its whole trip down the bore. There are two extreme opposite ways to get the same average pressure: high peak pressure with a low muzzle pressure, or low peak pressure with higher muzzle pressure. These are what fast and slow powders tend to get you, respectively. Because peak pressure imposes a safety limit, you just can't safely get to as high a velocity with fast powders as with slow ones, so they can't drive a bullet as fast as a slow powder can. But that slow powder will give you more recoil than the fast powder when it is held down the same velocity. For a recoil calculation, if you don't have QuickLOAD, with its convenient recoil calculator, this free PDF file from SAAMI has the necessary formulae.

What you discover is, yes, faster powders are more efficient. That is, a higher percentage of the chemical potential energy is tanslated into the bullet's kinetic energy. The figure of merit is called the Ballistic Efficiency (BE), and it is expressed as a percent. That improved efficiency is why, for a given velocity, you have lower charge weights of the fastest powders that can safely do it than of slower powders needed to get to that same velocity.

For .30-30 performance levels, you may find .30-30 performance powder is best. IMR 3031 would be a good choice. By dint of felicity or kismet, take Hornady bullet number 3031 and marry it to IMR 3031 powder. In an 18" barrel, QuickLOAD thinks you can load it to 2700 fps with a very slightly compressed load, but follow the manuals.
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Old July 30, 2011, 03:16 PM   #21
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I shot the Frontier over the chrony today ......

A box of Remington 140 gr factory loads gave me an average velocity of 2658 ..... I have not gotten any handloads together yet.

The gun did not recoil as much as I expected it to ....... nor was it all that loud, for such a short barrel.
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Old July 30, 2011, 06:02 PM   #22
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I ran a QuickLoad analysis for 7-08REM/140SierraSP/55,000psi/2.800"OAL/16.5" barrel.

RL-17 easily ran away with the top spot for velocity in the mid 2650's. As Factory loads run at pressures higher than 55,000, RL-17 gives you a lot of room to manuever faster as suits your purpose/conforms with safe workup. It's also 97.5% burned by barrel end, so muzzle blast/flash is minimized.

Runners-Up included Ramshot Hunter, AA4350, and W760/H414.
But I'd sure start w/ RL17.

~~~~~~~~~~~~~~~~~~
(I also ran it for a 162gr HNDY (BTSP#2845). RL-17 again stole the show for velocity (2,470fps) and burn (98%), but Hunter/AA4350/W760/H414 were getting closer.

Last edited by mehavey; July 30, 2011 at 06:13 PM.
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Old July 30, 2011, 07:40 PM   #23
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The 260 load was 45gr of RL-19. Primers showing pressure.
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Old July 30, 2011, 08:24 PM   #24
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603Country notes:
Quote:
(Ruger 260 with 16.5 inch barrel... 120 gr Nosler BT...Would a slower powder in that short barrel get me a significantly faster muzzle velocity?
As w/ the 7-08REM, the 16.5" 260Ruger can best use...

Reloder-17
Ramshot Hunter
Hodgdon H414
Winchester 760
Accurate 4350

(RL-19 is further down the list, and IMR4064 is even farther down the list (~90fps) at the same pressures.

No matter what, however, you're stuck w/ high muzzle pressures.
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Old July 30, 2011, 09:24 PM   #25
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Thanks Mehavey, that's really nice of you to provide the 260 info. Bad news, at least for the very short term, is that I don't have even one of the powders you listed. I'll give some thought and research time into which one to buy, though if anyone has suggestions (and are loading for a short barreled 260), I'm all ears.

Scratch that, I reread your info and I'll get the R17. Thanks much.
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