Ballistic Coefficient Question

[mrb1982]

I should really try to find someone with a brake to find out what it is even like.

Good apples to apples comparison there on the different bullets. Some guys get different velocities and whatnot but there are always gonna be a number of variables that one can not make a solid rule. Thanks for taking the time to post

 

[Broz]

I should really try to find someone with a brake to find out what it is even like.

Where you located?

Jeff

 

[Broz]

For what its worth in real numbers, same 300 win rifle , same powder lot, same seating depth going from a 210 VLD to a 215 Hybrid I gained an average of 40 fps across an oehler 35 with 1 grain less charge weight. And drops match perfectly to this velocity.

Not sure how that related to a 208 Amax, but this is pretty solid data for the 210 / 215.

Jeff

 

[WildRose]

Where you located?

Jeff

Same question here. A guy would really have to be living someplace way the hell out of the way to not be in driving distance of one of our members.

 

[mrb1982]

I am in Rapid City, SD. Kinda a far cry from a few of your guys. Around here, the common concensus is, "too noisy for hunting" which I can understand to some extent. But man, with some 180 Hybrids in my 7 RM, then add a brake, take that thing down darn near to a varmint rifle type recoil, I would probably shoot it so much the barrel would only last a couple years. hahaha Who knows.

 

[MontanaRifleman]

I am in Rapid City, SD. Kinda a far cry from a few of your guys. Around here, the common concensus is, "too noisy for hunting" which I can understand to some extent. But man, with some 180 Hybrids in my 7 RM, then add a brake, take that thing down darn near to a varmint rifle type recoil, I would probably shoot it so much the barrel would only last a couple years. hahaha Who knows.

Most of the hunting crowd anywhere are not long range hunting and therefore do not need large magnum cartridges, or do not need to see the impact of their shots. The only reason my rifles wear brakes is because is because of LR. I could shoot my 3 LR rifles (6-284, 6.5 WSM and 300 RUM) without brakes and I have put several hundred rounds through a Sendero 300 RUM without a brake. The brake makes them more pleasant to shoot but I certainly don't need one on my 6-284 and almost did not have one installed, but during break-in, I thought it would be a good idea so I could see my shots.

An unbraked gun is no more noisy than a braked gun... the only difference is the direction of the noise. That can be fixed with hearing protection which I wear as well with my unbraked 223 and 22-250.

 

[WildRose]

I am in Rapid City, SD. Kinda a far cry from a few of your guys. Around here, the common concensus is, "too noisy for hunting" which I can understand to some extent. But man, with some 180 Hybrids in my 7 RM, then add a brake, take that thing down darn near to a varmint rifle type recoil, I would probably shoot it so much the barrel would only last a couple years. hahaha Who knows.

I'm with MR. Guys who never shoot beyond 300yds don't get much real benefit other than fewer bruises.

If you are focused on precision however and shooting beyond that the ability to see your hits/misses is invaluable especially when it comes to quick, accurate follow up shots.

There is no disadvantage to installing a quality muzzle brake such as those we have recommended. You need to wear hearing protection with or without one. Some are easier on the shooter than others though and that is just the way it goes.

For the most part the people afraid of muzzle brakes have not actually shot them, they've just been off to the side of people using them when shooting at ranges and been hammered by the blast.

Earplugs are cheap, and the price of a good muzzle brake and installation is more than made up for in shooting enjoyment.

 

[mrb1982]

I don't mean to get off track from the thread but since brakes were brought up earlier I feel it is ok. If not, I apologize and somebody just tell me to move on.

I hear of people using the thread protector to put the brake on when they need or don't need it. Are a lot of people doing this? What's the overall concensus from folks on this sort of situation?

 

[Broz]

Use to have a protector made for every new build I did. But after seeing them sit on the shelf, and not even one of getting use once, I no longer am interested in them for my needs. In fact I seldom even take brakes off even during cleaning these days. Most of the newer design side discharge allow cleaning while on.

Jeff

 

[sp6x6]

Its one of those personal choice things. I run usually no brake most season for hunting,but I have what I call a rig gun and a packer. Packer sees thick, much thicker than the kind of country Broz hunts. I grew up in MT and have hunted most of it and some ID and thick in AK.My rig gun always braked , packer not. And I have shot more than one bull close in timber w/ brake and said No more.Could not here for hours walking out,340 wby was smallest I shot in last 25 yr. 10 years no brake. I put my hoop type plugs in to shoot even hunting. But I dont want to miss a opportunity.I have tinituios also and work constuction. I hunt elk hard archery and you need to hear them bugle.

 

[1simplemann]

Now that you have your rifle, work with what you have. Find its limits and your limits. Maybe when you wear out your barrel, there can be a similar conversation that involves the relative merits of .30's, .338's, and maybe even .375's.

Enjoy your new rifle and GOOD LUCK!

This rifle may get passed along to guy who's house just burned down to the ground. Total loss! No insurance either. Bad deal for him and his family.

 

[1simplemann]

In reply to the original post, to clarify things here. There's been a lot of this is better than that discussion here without many actual numbers quoted.

I'm going to use Hodgdons load data here, comparing like with like, to save any high pressure handloads being compared with factory velocities etc etc. I know exactly what we get velocity verses pressure measured with the Oehler 43 Ballistic Lab for all these options, but for the sake of transparency we'll go with Hodgdon's latest data off their website. And our data differential pretty much matches Hodgdon's anyway, even if we are loading to higher pressures and velocities.

In the 7mmRM with the 180gn Berger G7BC of .345, Hodgdon list 2920fps for 59,600fps with 71gn of Retumbo.
In the 300WM with the 208gn A-Max they list 2915fps for 61,300psi with 81gns of Retumbo. They don't actually list the 215, but in our experience you will loose about 50fps to 75fps from the 208 to the 215 (the general rule of thumb is 100fps per 100gns of bullet weight for these sized cartridges), so lets choose the lesser velocity loss and say 2865fps. G7BC .356
With the 230gn Berger G7 BC .38 for the Target (the OTM is .368, but we'll assume the higher BC of the Target), they say 2774fps for 61,300psi with 72.6gns of 7828.

If you run these numbers there is very little difference in trajectory and wind drift to 1500 yards between the 180gn and the 215gn. The 180 drops slightly less than the 215, and drifts ever so so slightly more. If you assign the same pressure for both (remember we had 59,600psi for the 7mm verses 61,300psi for the 300), which will have the 180 doing 2940 odd fps, the 180 will drift identically to the 215 to 1500 yards, with less drop. Beyond this the slightly higher BC of the 215 will start to edge it ahead.
As far as actually hitting your target in the first place, there is nothing in it between the 7mm RM with the 180gn Berger and the 300WM with the 215 Berger.

Yes, the 215 will have an energy and weight/diameter advantage that theoretically is an advantage in terminal performance, all else being equal. And it will have a slight theoretical barrel life advantage, about 6% more. But it does have quite a bit more recoil, around 30% more.

When you step up to the 230gn then it beats the 180 and 215 in the wind, at the expensive of more drop, and a bit more recoil again.

That puts some real numbers in this debate.

Thanks for the numbers!

 

[mrb1982]

This rifle may get passed along to guy who's house just burned down to the ground. Total loss! No insurance either. Bad deal for him and his family.

That sucks for the guy who lost his house. That is great that you are gonna help him out like that. It says a lot about the kind of person you are

 

[NZ Longranger]

As far as brakes are concerned, we use both permanently attached and removable brakes, depending on the rifle. In our lightweight walkabout hunting rifles, we take our brake off and use a thread protector for stalking in bush country when we will have to fire a quick shot offhand and won't have time to use hearing protection. Then when we get to a lookout where we might fire a long shot and will have time to use hearing protection, we put the brake back on.
This system works really well on rifles up to the big 7mms, and we mainly use radial brakes as it doesn't matter if they creep round a bit on the shoulder with the continual taking on and off. A good radial will comfortably tame any 7mm, right up to our maximum capacity 7mm FX (338 Lapua max improved), pushing a 180gn Berger at over 3400fps. On the big 30's and larger, we use more efficient at stopping muzzle jump directional and angled port brakes, and they don't suit the taking on and off so much. But generally, these big rifles aren't used for stalking as much, mostly for long range, so there's plenty of time to use hearing protection. We do not shoot the braked guns without it. If you do you will regret it as you get older.

There is not as huge a difference between the radial and the directional brakes with the amount of debris blown about in our opinion. All brakes blow dirt and dust around, make no mistake, and the rearward angled ones are worse than most radials at getting crap in your eyes. But the big guns, especially if lightweight like our under 8 lb all up 338 FX, must have them to be shootable.

Really, there is no downside to having a brake fitted, as you can always decide not to use it if you don't want to. And on any all round or specialist long range gun I would always fit one to be able to spot my shots better and minimize the chances of a Weatherby eyebrow when shooting prone.

Greg

ps I'm not doubting the velocity anyone gets with the 215's at all. The point is comparing the velocities at the same pressure. Unless you have pressure measuring equipment and are comparing like with like, you can only use published data like Hodgdon where they do list exact pressure. As I said, we do have Oehler pressure testing gear and are able to do accurate and direct comparisons, and our differential will all the bullets in this debate matched Hodgdon's data, which is why I was satisfied it was accurate to use it in my comparisons.
Emotion always seems to creep into these caliber debates sooner or later, even with the best intentions!