Author Topic: Finding Powder or Seating Depth 1st (Read 730 times)

The grouch · « **on:** October 22, 2003, 10:36:07 PM »

Great site! New to reloading:
I have a New Encore 15" 7mm-08. 1st hand gun. Never done any reloading before, But have fired hundreds of thousands of rounds in my 50 years of hunting & shooting. Wondering what do I determine 1st. The best powder or the seating depth?
Also how do you determine the correct case length? Not the COL I've learned that here on the forum. The case length?
Thanks

The Shrink · « **Reply #1 on:** October 23, 2003, 01:10:09 AM »

Grouch

Woah! Stop now and get and read thoroughly one or two good, basic reloading manuals. I can reccomend the Sierra Bullet one, Lyman is good, but read one before you go any further. They all have case dimensions provided on the data page, that's how I know you haven't read one! You will find reams of basic information about the loading process that is essential to know before you load anything.

To answer your specific question, you first choose the bullet you want to use on the basis of it's characterists and your intended use. Then you try three or four different powders at various loadings to find your most accurate load. Only then do you make minor changes to that load to refine it.

For hunting accuracy, i.e. 5 rounds in two inches @ 100 yds., if you can't achieve this without refining your load further, you need to look at your firearm, because that's the more likely culpret.

The grouch · « **Reply #2 on:** October 23, 2003, 12:30:46 PM »

Shrink, Thanks for the reply.
I know what the books say as to the case dimensions. They also quote the OAL. But the books quote on the OAL is not neccessarily what your Barrel is. Right?
Although there are different ways to find what your guns OAL is. I know that you then back down from there. 1 manual says,"-.005 thru -0.020. So where do I start for the OAL. What the book says? 2.80? Even though after measuring the OAL is 2.912.
I thought maybe there was ways to find the correct case length also.
Thanks,

The grouch · « **Reply #3 on:** October 23, 2003, 12:42:45 PM »

The Shrink,
I forgot to mention that I am using 140gr. Nosler Ballistic Tips. Want to use this round for hunting Whitetails is Wisconsin, and then Mulies, and Prong Horn. Been told by the local Shooter Supply to use what the Nosler book recommends in powder. 35 to 40 gr. of H335.

Iowegan · « **Reply #4 on:** October 23, 2003, 02:04:06 PM »

Grouch, You have selected one of the most accurate cartridges available. Here's a good starting point: Hornady #2825 139 gr BTSP bullet and 40 gr Varget powder. Check this web site for bullet seating and chamber length tools. Below the graphics are some good articles (requires MS Word). http://www.cactustactical.com/reloading/reloading.html

The grouch · « **Reply #5 on:** October 23, 2003, 10:48:07 PM »

Iowagan,
Thanks much! I just ordered that guage/tool. I'll also try the load you suggested. Again thank you and all the guys on the forum. It's nice to be able to go somewhere and get info and help. Hopefully I can be a help to someone, sometime!
Thanks, :grin:

The Shrink · « **Reply #6 on:** October 24, 2003, 12:47:27 AM »

Grouch

I see your question, but it's still more important to find your accurate powder/bullet combination load(s) than to mess with seating depth. You are right, seating depth changes with the oglive of the bullet, some are more abruptly curved than others, and will contact the rifling sooner. Chambers are also not all identical, they are made accurately to speck, but there are variations.

To find your chamber length, take an unprimed cartridge case, inside lube the neck, place a bullet just barely into the case, and place this case in the chamber. In a break open, simply slowly and easily push this case in until fully chambered. (You don't want the bullet to stick in the bore.) Take it out and measure the length of the round and you have the rifling contact point. You can then adjust your seating back from this point as much or as little as you want.

Let me again say that this comes after you find the load(s) that are most accurate in your chamber/barrel combination. There's no point tweaking something that won't be satisfactory no matter how much you tweak it.

If you are going to go as far as adjusting seating depth, and in a single shot, you may as well index your rounds as well, making sure that the case is always placed in the chamber and reloading die in the same manner each time. Simply file a nick on the rim and you have a reference point.

Duffy · « **Reply #7 on:** October 24, 2003, 06:43:55 AM »

Grouch;

Here's what I found in my 708 that will maybe help you narrow things down a bit and get you up and running a bit quicker. Just remember that all bbls are different.

Varget and IMR 4064 work better than H335, I am presently using VV N550 with a 140 Nosler BT with great results but it's a bit spendy for starters. Varget gives good velocity and pretty good accuracy while 4064 gives better accuracy and less velocity. Cases are WW and primers are WLR. I full length resize just enough so the action will close easily, this gives best brass life and accuracy. Watch brass length because it seems to grow quickly at least in my gun by the 3rd-4th loading.
Most of the ball powders give a lot of muzzle flash ie. H335, AA2460, H380.
Mine shoots best with the bullets seated .030 off the lands, any closer and pressure becomes a issue and accuracy falls off. Have gone out to .045 with no ill effects so there seems to be a bit of a window, yours may be different. I haven't tried any Hornady bullets but out of Sierra, Speer and Nosler the Noslers shoot the best with the Sierras right behind. A bullet comparater is a handy tool, if you are getting into this might I suggest the Stoney point gauge mainly because they make a cartrige headspace gauge that also fits the same mandrel that goes on your caliper. I have the Sinclair nut type and while it works fine the Stoney is more of a system. Lot's of info here on the boards and in the books, just take your time and enjoy and by all means be safe!

Ryan

Iowegan · « **Reply #8 on:** October 24, 2003, 04:28:58 PM »

Wayne, Next time you start working up a load, try this: 1. Buy the bullets you want to use (target, hunting, varment) preferably a weight that is best suited for your rifle's twist rate. 2. Determine optimum bullet seating depth by the method above or by using a bullet seating depth gauge (ogive should be .010" from rifling). 3. Find a load in a reputable reloading manual that closly replicates "factory load" velocity for your bullet weight. 4. Deprime, size, and anneal your cases. 5. Use a case length gauge to determine optimum case length (.005 short of where the case mouth bottoms out on the chamber bore). Trim cases if necessary. Most chambers are way deeper than SAAMI trim length specs so trimming is usually not necessary. 6. Load some test ammo starting at the middle scale of the recommended powder charge and work up a grain at a time. Most loads "dial in" toward the higher end of the chart.

I have used this method time and time again with outstanding results. I find tuning the powder charge first then adjusting the bullet depth is counter productive. Eventually you will stumble on the right combination but why not seat the bullet right the first time then tweek the powder charge? Any rifle with a decent chamber, bore, and crown will respond to this technique.

BruceP · « **Reply #9 on:** October 24, 2003, 05:02:19 PM »

I have to say that I tend to find a good consistant powder charge giving good velocity first. I do start with my bullets aprox. .010 from the lands. Then I will start seating bullets deeper by about .005 at a time and shooting a group with each depth. If I know I pull a shot in a group I will repeat that depth if not I will continue and watch the group size. In the rifles I have tried this in the group will usually get smaller with each change in seating depth to a point then start getting larger again. at this point I go back to the last depth and load and shoot more groups at that setting to confirm the accuracy. In a Remington ADL 308 Win. and in a Ruger MKII 257 Roberts I have had this method take loads shooting one hundred yard groups of around an inch and a half at .010 off the lands and cut the group size to under a inch at around .030 to .035. The 308 would shoot under 3/4" if I did my part and this was with 150gr Winchester Silvertips bought in bulk.(the old style not the new Ballistic Silvertips)
I will also have to say that if I were to reach .050 off the lands (I have never went this far yet) and still not get the groups I want I would stop and try another powder or bullet as I feel (not know but feel) that presures may start to rise to much if you go much deeper.
BruceP

Duffy · « **Reply #10 on:** October 24, 2003, 06:34:51 PM »

BruceP;
Nice to see someone else has guns that prefer deeper seating! I don't think any of mine and a few others I've tried shoot excellent .010 off the lands. Most are more like yours, in the .030-.040 range. When I seat closer to the lands the velocitys spreads are wild and so are the groups, plus reducing the charges, trying different powders/primers/bullets didn't help.

KYODE · « **Reply #11 on:** October 25, 2003, 02:23:29 AM »

41.5gr of h4895 with 120gr nosler bt's gave 2800fps and excellent accuracy in my 15" 7-08. only the second load i've tried. 2.87oal. the first load was 40.0gr of the same powder, and gave fair accuracy with just over 2600fps. both loaded close to the lands, but don't know precisely yet, how far off. :roll:

The Shrink · « **Reply #12 on:** October 25, 2003, 03:20:29 AM »

Grouch

I hope you're still reading this. You now have two excellent and well thought out ways of establishing your most accurate load. My advise, and I think all here would echo it, is: Choose one and start burning powder!

It's only by pulling the trigger, with a conscious knowledge of what you are trying to accomplish and how you are going to accomplish it, combined with good record keeping, that you will ultimately answer the question for you with your gun.

The grouch · « **Reply #13 on:** October 26, 2003, 01:02:33 PM »

Fellow Shooters,
WOW! :shock: Thanks so much for the help. Sure glad I found you Guys.
Who knows maybe sometime I can help or contibrute to someone that needs help or advise.
Again Thanks! Keep up the good work!