7mm STW build in progress... Budget LR Hunting Rifle Phase I

[Rent Outdoor Gear]

Great pics and it looks like your dope is pretty dang close at 500! what'd you guess your speed at?

Mike

I guessed 3075 fps, which told me to dial 5.6 MOA with a 250 yard zero. I shot this group dialed at 5.5 MOA.

Since my 250 yard group was .3 MOA low, I re-ran the numbers and I come up with a velocity of 3167 fps with an actual zero of 233 yards. That lines up giving me -.3 MOA at 250 and -5.5 MOA at 500.

3167 fps with a 160 grainer is a little faster than I expected for a factory load. The only caveat is that I did not shoot the two marks at the same time and place. Temp was close, but I should run another string when I get a good day at various ranges to dial in that velocity number better. The elevation of the 500 yard shots was 1500 feet higher elevation. Actual velocity is probably 3125-ish.

I need a chrony among a long list of other "shooter" needs.

Coop

 

[Travis Bertrand]

Chrony is a must! A true game changer for load development and choosing an accurate load.

 

[HellsCanyon]

Chrony's are nice, but aren't necessary especially if you aren't shooting a whole lot of calibers... As long as you got a place to stretch your rifles legs and be close on your environmental conditions, a chrony isn't needed to figure out your velocity. If you're wanting to record ES and SD of your load development then go for it. But a ladder test, tuning seating depth, then confirming velocity at distance will get you the same data. I think your velocity of 3167 is probably closer than 3125. My 280AI is real close to your numbers launching a 168 at 2950 fps and by changing pressure by 1.5" (roughly 1500' in elevation change) and 15* temp variation my trajectory at 550 yards only changes .47". With your higher speed it'll probably be right at .4-.45" difference. That's less than 1/10th MOA. Most shooters can't hold that less than 1/10th MOA that conditions will vary the trajectory at that range so it's almost a moot point. So I'd call 3167 fps right about on the money until you can really get more accurate weather conditions at your location during time of shot. But as you can see you're dope will change VERY little from 600 yards and closer no matter the conditions...

Mike

 

[Travis Bertrand]

Mike, one area it has really helped me is in load development,

Example,

.243 with 58gr vmax, while working up a load, I found one powder combo deadly at 100yard. 1/2 moa but I was getting almost 60fps difference between shots. You walk that out farther and you could see groups spread out.

I could have learned that about that load the hard way by shooting farther, more ammo and more time.

Not only does a chrono tell you speed of the projectile, it also helps measure consistency.

 

[Rent Outdoor Gear]

I have a shooting chrony beta, but it hasn't been working for a while. I didn't need it when I was working at Hoyt because we had a couple of super nice Oehler's that were wicked accurate. Probably ought to send mine in to shooting chrony and see if it can be repaired. Heck it might even work outdoors. The issues I was having were inside. For the money a chrony costs, it's worth having for archery and rifle setup. Real time saver with an archery setup using arrow trajectory software. Crazy accurate too.

DC

 

[Whisky]

I need a chronograph. I would feel naked without it, both for archery and rifle. They aren't that expensive, although some of the cheaper ones work, some don't, or work when they want to. I used to have a Shooting Chrony Beta Master and it got real picky when it wanted to work after about a year or so. I now have a Competition Electronics ProChrono Digital and it's been much better. Think you can find them for $100 + shipping at a couple archery supply stores.

 

[Matt Cashell]

Mike,

I am kind of shocked about your opinion on chrony's. I am with the Dr. on finding good loads, and chrony's are the best tool for checking load pressure, IMO. You can go way over SAAMI without seeing pressure signs on the primer, brass, bolt sticking, etc. (depending on the gun). JMO.

I find a chrony as essential as well, but they don't have to be fancy. I have a cheap "Prochrono" that has been accurate with my drops for years, and keeps my load testing on track.

 

[HellsCanyon]

Mike, one area it has really helped me is in load development,

Example,

.243 with 58gr vmax, while working up a load, I found one powder combo deadly at 100yard. 1/2 moa but I was getting almost 60fps difference between shots. You walk that out farther and you could see groups spread out.

I could have learned that about that load the hard way by shooting farther, more ammo and more time.

Not only does a chrono tell you speed of the projectile, it also helps measure consistency.

I am in full agreement that they are a solid tool for working up loads. Though I don't deem them absolutely necessary. My comments are more regarded towards verifying data at distance and figuring out accurate fps. Though I will admit that is an EXTREME case of inconsistent loads... I'm curious here, but how were you dispensing and measuring your powder? With powder charges individually measured to within .1 grains the most extreme ES we've had has been less than 25 fps and usually they are within 10 fps.

Mike,

I am kind of shocked about your opinion on chrony's. I am with the Dr. on finding good loads, and chrony's are the best tool for checking load pressure, IMO. You can go way over SAAMI without seeing pressure signs on the primer, brass, bolt sticking, etc. (depending on the gun). JMO.

I find a chrony as essential as well, but they don't have to be fancy. I have a cheap "Prochrono" that has been accurate with my drops for years, and keeps my load testing on track.

For Darin's situation I don't see a chrony being essential. My reference for them not being needed was more geared towards figuring out your dope at distance. And as I mentioned, unless you plan on shooting many different rifles and many different loads, they aren't ESSENTIAL. They are a great tool and every shooter who plans on sending lots of rounds down range will no doubt benefit from them, but it's just my opinion that they aren't needed for many people out there. Though we are a group of hunters/shooters on here who like to understand and dial in every piece of our kit so I understand
and appreciate the desire for a chrony.

There is quite the debate on if you can accurately estimate chamber pressure with a chrony. Personally we've never done it, and don't plan to. Not saying it can't be done, but we've never had a need for it (YET). A big part in this has to do with your quality of barrel and you caliber. In certain calibers, we've noticed that a particular barrel manufacturer is consistently running 50-75 fps FASTER than other aftermarket high quality barrels with identical twist rates and identical loads. There's some objective testing out there where they've seen pressure rise to velocity change at 20:1 ratios, pretty tough to measure chamber pressure accurately by just going off of velocity. We've never had an issue with pressure if we paid attention to how the gun was shooting and the inherent signs of pressure you mention like flattened/blown primers, bolt sticking, ejector marks...etc 90% of our rifles are shooting loads that are way over max listed in any modern reloading manual and they are safe. Don't misunderstand this for "Hey HCA is shooting over max pressure, we should too!"... Safety is paramount and you can seriously get hurt if you are stupid about it. With that said, my hunting pard and gun builder has found reloading manuals from the 60's and 70's that had WAY higher max load listings than current reloading manuals. Everyone is scared of a law suit and for good reason. You don't want to be loading up grampa's old Savage with max loads and expect it to be safe. We always start below recommended max levels and work up from there paying attention to each individual rifle's appetite and tolerance...

For those of you looking to get into a chrony for rifles, you should really check these out, have been getting phenomenal reviews over the last year and they are definitely on my list of goodies to get: http://www.magnetospeed.com/

Mike

 

[Matt Cashell]

Cool chronograph system there, Mike!

I understand what you're saying about going over SAAMI doesn't necessarily make for a dangerous load, and I agree.

I also have noted that some barrels are "faster" than others.

My point was that if your muzzle velocities are significantly higher than listed max velocities in a current manual, you are likely exceeding the SAAMI pressure limits, regardless of whether it is showing pressure signs or if your particular rifle can safely handle the additional pressure.

Personally, I like using the chrony so that when I get around the listed SAAMI velocities, and find the accuracy I am looking for I am good to shoot.

Using a chrony also saves me time getting my initial data for field verification.

 

[Shrek]

I'm with Mike on pressure , saami specs , and velocity. I work on pressure signs and don't worry what someone in consultation with a lawyer wrote. While I never build ammo over book for others , most of my own loads are over and some have been way over , like 8.5% over. I looked at an old manual from the 70's a friend had and the loads for powders and bullets the were comparable were all several whole grains higher. I've gotten over my velocity addiction and most of my new loadings are coming down to save brass life but not because of some printed industry standard or velocity predictions.

 

[Rent Outdoor Gear]

Cool unit, but if I strap that sucker to an arrow I think there's going to be a problem!

Coop

 

[Justin Crossley]

I would not use a chrono like that myself. I wouldn't want something hanging on my barrel when I'm trying to shoot groups. I think that could totally change how your rifle shoots.

 

[HellsCanyon]

I would not use a chrono like that myself. I wouldn't want something hanging on my barrel when I'm trying to shoot groups. I think that could totally change how your rifle shoots.

A legit concern and one I first shared... While I haven't used one personally, there's been an ongoing review thread over on SH.com for better than a year with nothing but good things to say and I know a few of the guys who are vouching for them.

Mike

 

[Justin Crossley]

You should buy one so I can test it.

 

[HellsCanyon]

Want to go Halfsies with me?

Mike

 

[Travis Bertrand]

I am in full agreement that they are a solid tool for working up loads. Though I don't deem them absolutely necessary. My comments are more regarded towards verifying data at distance and figuring out accurate fps. Though I will admit that is an EXTREME case of inconsistent loads... I'm curious here, but how were you dispensing and measuring your powder? With powder charges individually measured to within .1 grains the most extreme ES we've had has been less than 25 fps and usually they are within 10 fps.




Mike

Sorry for the delay mike, I dispense powder via Lyman 55 or a uniflow depending. I have tested the common theory of weight +-.1 and also going by mass. I am a firm believer of loading by mass. I set my Lyman up at my presets and measure every 10th one to see. I have found most of my accurate loads loading this way. Chrono and paper prove it. The load that was inconsistent I made an example of was measured with a uniflow measured off of weight +-.1.


Yes I'm in full agreement with you on not relying on a chrono to dope your rifle. Get close with with it only and the only way to dial in your is with throwing lead down range!!!

 

[Shrek]

Drhorsepower , are you saying you rely on volumetric measures like the uniflow and not by scale every time ?

 

[Travis Bertrand]

Drhorsepower , are you saying you rely on volumetric measures like the uniflow and not by scale every time ?

Yup. I have found volume to be more accurate than weight in most of the loads I have tested. Granted I haven't tested all powders or loads.

 

[Shrek]

I might go that way with a fine grain ball powder but there is no way I'm doing that with an extruded long grain powder like Retumbo , H1000 , or IMR 7828? Way too much internal bridging in a volumetric measure for my tastes. I always use a beam scale and trickle up to finish a thrown load. If I trickle too much I dump it back in and start again. I never try to remove powder from the pan. I throw Leverevolution for my friends 30-30's but thats about it.

 

[Justin Crossley]

I use an electronic scale and powder dispenser. I used to do the balance beam and trickler but this is much faster.
I would only "throw" powder for plinking ammo.