Help the new guy

[Tango2020]

Long story short I reloaded a few years ago, stopped for 15 years and now back at it. Rifle is a 25-06 Ruger M77. Last week I loaded a few sets to try and work up a load for a Sierra 117gr BT Spitzer using H4831sc. The results were very disappointing and I'm not sure why. I loaded from the starting load in the speer manual and increased .5 grains up to the max with groups around 2.5" at best at 100 yards. I set the OAL at .010 off the rifling. This Rifle is fairly accurate with Remington factory loads with 1" to 1 1/2" groups but I was surprised not to get a group with the Sierra's. When I loaded for this rifle 15 years ago I think I remember having a hard time with accuracy using Boat Tail bullets. Is it possible for a rifle to not have good accuracy with BT but accurate with flat base bullets.

[Unclenick]

Welcome to the forum.

Flat base bullets are typically easier to get accurate short range loads with. There are several reasons for this. One is that all bullets acquire a certain amount of yaw at exit from the muzzle, and muzzle blast is part of the cause. A boattail dwells longer in the blast stream as it clears the muzzle over a length instead of all at once, exaggerating the effect of any tiny bullet or muzzle geometric asymmetry.

Another cause, pointed out by Bryan Litz in his book, is that it is easier for a manufacturer to form a perfectly square and symmetrical flat base than to form a perfectly symmetrical boattail. Base perfection is essential for minimizing yaw and deflection of the bullet off alignment with the bore.

Finally, for a given weight, the flat base bullet has a longer bearing surface, so it lines itself up better in the bore. The boattails don't do their best until they have flown far enough for gyroscopic spin to settle the yaw out (going to sleep). You often get better results from boattails at long ranges, after they've settled and where their higher ballistic coefficient keeps the wind from pushing them quite as far. Flat bases do best at short ranges. I find them hard to beat to 200 yards. Some .30 cal flat base (Berger match bullets) will outdo same-weight boattails to 500 yards.

Writing in the Precision Shooting Reloading Guide, Dave Milosovich points out that one day he was loading for a 220 Swift he could never get to group better than 5 shots into 3/8". In switching bullets to a 50 grain Nosler BT, he turned the micrometer on his seating die the wrong way and wound up seating 20 rounds with the bullets 0.050" from touching the lands instead of 0.020" off the lands as he'd intended. He considered pulling and reseating them, but decided just to shoot them up in practice. To his astonishment, his four 5-shot groups were two 0.25" groups and two bugholes in the 1's.

The lesson is that every bullet tends to like a different seating depth and no particular number should be assumed to be best until it is tested. Berger has found some of its VLD shapes want to be as much as 0.165" off the lands in some guns. The best depth for your bullet in your gun has to be found, same as the best powder charge does.

[TATER]

It very well could be the bullets, That rifle could prefer a lighter bullet and not
necessarily have anything to do with the boat tails.

I would recommend moving in smaller increments of point .3 grains. As you could
Move right past a node and not know it.

Work your load out before you start playing with the seating depth as
you are just adding another variable to deal with. Save that practice
for the last fine tuning.

[Tango2020]

Thanks for the advice and response. I think my rifle may have an issue with BT's and bullets on the upper side in weight. Even with factory ammo it always shot better groups with 100 gr than 120gr. I'll try some 100gr flat base bullets and see how that goes. I always try to migrate to the 120's because I'm afraid that 100's are too light for white tail though I'm starting to change my thinking on that. I shot a Buck last season with a 100gr Remington and he didn't go anywhere.

[flashhole]

A 100 grain bullet will do just fine on White Tail deer. FWIW - my Rugerd #1V 25-06 didn't shoot that bullet worth a darn either. I have had very good success with the Nosler 100 grain and 115 grain Ballistic Tips (BT not to be confused with Boat Tail). I found my gun has a strong preference for Retumbo Powder with both those bullets. H4831 works really well with 87 - 90 grain bullets.

[Doodlebugger45]

Sometimes a certain bullet and powder just won't do well in a given rifle. Who knows why. It sounds like you used a reasonable bullet and powder to start with and the seating depth sounds reasonable. Trying a different bullet is the obvious next step. But you still have a bunch of the original bullets sitting there. It wouldn't hurt a thing to try them 0.050" off the lands or even a different number. I'll take a bet that the factory ammo is loaded short of that. And you might check to see if other manuals had a higher max than you used. I am guessing you didn't have a sticky bolt to indicate high pressure. So take it up in powder weight a little bit at a time. Some rifles like that.

And finally, you might try a different powder. You used my first guess for that chambering, but you never know what H4350 might do. Or H1000 for that matter.

[TXJohn]

Tango 2020, I do have one rifle that will not shoot boat tail bullets at all finally gave up and just load flat base bullets it is a 22-250 AI.

As far as your 25.06 I have owned one since 1970 and have loaded 117 Sierra's also with IMR4350 My load is 49.0 grs. this is a max load so please start 10% under but has been safe in several 25.06's I have owned over the years hope this helps. This load usually shoots 1 moa or under.

[Tango2020]

Thanks for the input guys. Glad to know I'm not alone on the BT's. I'll go back and play with them a little after I work up some flat base loads and have something for comparison. Great advice on the site here and I have learned much.

[Rifletom]

I've been loading 120gr Hornady hp's over 51.0gr of H-4831sc for some time now, and this works well. Rifle is a Ruger MKII. MV avgs about 2925-2950 fps.
The mulies and antelope don't seem to care for it tho!

[Tango2020]

I have a new concern I need clarified. In determining the oal things don't seem to match up. I have used the method of smoking the bullet and then the dow rod method (not as accurate I know but just to double check myself) and on both I come up with an oal that is shorter than the manual. I thought just off the lands would be longer. Am I missing something? The specifics are:

A Sierra Game King 117gr BT 3.164" touches the Lands
Manual only shows a 120gr but oal of 3.200 tested and 3.250" max

A Sierra 87gr SP touches the lands at 2.996"
Manual said it was tested at 3.115"

By my thinking if I went by the book I would be pushing the bullet into the lands and increasing pressure which is wrong,right?

The gun is a Ruger M77 and I'm using the Speer #14 manual

[a7mmnut]

First, if you still have the rifle in the factory stock, take it out and get rid of those pressure ribs all the way down the length of the forearm wood. Shim and check if necessary for a good 1/8" free float fit. Coat with lacquer after removing the wood. Bedding that lug is a task you may or may not want to take on by yourself, but that barrel must float to shoot well. I owned an older M77, and loved that gun! I also loaded for a friend's newer Mark II wood .25-06. It's one of my favorite calibers.

Ruger puts a .25 bore in a factory .30 blank, which makes for plenty of meat and a stiff barrel. You don't have to settle for 2" groups. I always loaded bullets from 90 to 120 grains with BTHP's or BTSP's and got great results from Nosler, Hornady and Sierra bullets. You should be shooting at least 3/4" groups once you find the right niche. We often shot around 1/2" with 100 grain Noslers (solid base). With the 100 gr. bullets, I went with 52.0 grs. of IMR 4350. Stop at 48.5-49.0 grs. with the 117 or 120. If that doesn't work, switch to H4831. Always light them off with CCI 250 mag primers or equivalent, and make darn sure the inside of the primer pockets and case bottom is free of any signs of wet lube.

-7-

[Tango2020]

Thanks A7. oddly enough I sanded down the one at the end of the forearm today. I read that you should be able to slide a dollar bill between the barrel and the forearm which I sure couldn't do that. I thought that was the only one but I better look again. I haven't shot it after sanding.

[a7mmnut]

As far as the OAL goes, this is how I check:

Make a "dummy" round for each bullet you load. Seat to the nearest .100" LESS THAN your target OAL. Chamber the dummy and close the bolt. Run a wooden dowel or solid cleaning rod with flat tip down the barrel until it touches the tip of the bullet. Hold in place and mark a ring around the rod at the muzzle crown as thinly drawn as possible. Remove the rod and dummy and take the bolt out of the rifle. Drop the bullet you intend to reload down the chamber throat and hold very light pressure on it with another, shorter rod. Run your marked rod back down the barrel until it just touches the bullet. Use VERY LIGHT presure, so as not to back the bullet out of the rifling. Mark a second, very thin ring around your muzzle crown. Remove the rod from the barrel and measure the distance between the two marks. Add that number to the length of your dummy round OAL. That is the exact distance to your rifling.

I have dummy rounds made up for all of my favorite calibers and bullets, and they can be reused for years. I always check them before use, and this method has never failed me.

-7-

[Unclenick]

Tango2020,

Max COL is just to ensure fit and feed from the magazine. It's no guarantee all bullets will fit at the maximum. A long shape will have longer COL than a blunt shape.



Despite what I illustrated, I am a little surprised at a commercial chamber having a throat so short that you get the results you do. As you say, Sierra's own manual has those bullets longer than you can fit. Add to that the accuracy problems you are having and I think I would take the gun to someone with a bore scope who can look at the chamber throat. At least, call Ruger and ask if they run their freebore shorter than normal? If not, you can legally send it to them directly for a free check out and they can legally return it to you directly an FFL holder becoming involved.

If you don't want the shipping costs, then it might be worth having a local smith run a 25-06 finish reamer in on a T-handle to see if any metal comes off in a couple of very light turns? Guys at the CMP forum have been having to do that with about half the New In Wrap Garand barrels they've been selling. Not sure what the issue is, since I haven't had one to scope myself.

FYI, if you load bullets with exposed lead noses, nose slump can mess with ballistics in a high acceleration bullet. Bryan Litz notes that Sierra noses slump least of all the bullets he's tried, but that's not zero. Personally, I would stick to hollow points in a high acceleration chambering for that reason.

Another thing that can be an issue that Harold Vaughn measured in the .270, is core slip with very high acceleration. This is where the jacket slips over the core inside the barrel because it spins up too fast for the bond between them, and the two don't equilibrate until the bullet exits the muzzle. By then there is core distortion, so it opens groups up. I don't expect it in the narrower diameter bullet at the velocities you get from your bullet weights. But if you suspect it may be an issue, you could try a bonded core bullet of some kind to see if there is a difference. Alternatively, you could also try some Trail Boss squib loads to see if they do better with accuracy at lower velocity. Folks routinely get 1" groups at 100 yards with them. They take recoil, barrel deflection and muzzle blast out of the picture as contributors to accuracy issues. Just something to try.

[mehavey]

I am a little surprised at a commercial chamber having a throat so short that you get the results you do.

This is also the case with new Winchester Model-70/30-06 that I wrote about back in December which I couldn't get to digest anything. Seven bullet designs from 150 to 180gr; three manufacturers: Speer, Hornady, Sierra; six different powders.... Horror story.

It also had a short throat as shown by comparison with (a) Sierra's [5th ed] recommended 175SMK OAL of 3.29"; and (b) the graphic below showing the actual Distance-to-Lands for the bullet as measured (over six different projectiles) using my Stoney Point tool...


The gentle reader can quickly see that at Sierra's recommended OAL of 3.290 I would have been jammed into the lands by a good 16 thousandths. (FWIW I found this short throat to the be the case for all bullets measured.)

I'm not sure what's going on here since I called Winchester and they said "yup, that's the chamber dimension..." But it does make me wonder for the casual reloader and what he (she/it) has to contend with when only having a manual to go on....

~~~~~~~~~~~~~~~~~



post script: I sent the Model-70 that was giving me so much trouble back to Winchester along with all the targets/loads/descriptions. They sent it back with a test target that showed it ate Commercial ammo just fine. Problem was it had barrel whip that Lash LaRue would have enivied, that "hot-glue" bedding that's all the range right now, no support under a "sporter-weight barrel, and a squared-up/countersunk crown. With handloads (and then even commercial after a half-dozen shots) it slung stuff into unpredictable 5"-6" "patterns" (They certainly couldn't be described as "groups")

I finally had the hot glue dug out and replaced with pillar-bedded epoxy, the barrel/chamber bedded for 1-1/2" ahead of the receiver ring, the barrel channel relieved another 30-thousandths, and the crown re-cut to a classic round-over.

Today was first day out with some blase' old son-of-WC852 to baseline...



At least it's "well-behaved" enough now to begin the search for what it really likes.

[Tango2020]

That is a lot of info to digest for a new guy. I feel confident that the measurements that I'm getting are Accurate and I think I need to go by my chamber and not the manuals dimensions. I'll load several flat base and lighter bullets and see what the results are. Seating off the lands at the measurements I'm getting. If things still aren't coming together I'll take other steps but I think I need more data now. I'll report back. Thanks for all the info.

[mehavey]

"....go by my chamber and not the manual's dimensions...."

You are exactly correct. On that same note I would trust a well-measured rod method over the smoke method, and I'd target 20-thousand's OFF the lands to start.

Important NOTE: Every bullet design will have a different distance-to-lands. It's a pain, but measure several bullets of each design to get an average for each design. Then you can load from those number(s) from then on.

Another Note: Given you have a "custom" throat, I'd suggest getting the Stoney Point [Hornaday] Gauge along with the required/modified cartridge case for your rifle to really nail it down in the future.

http://www.midwayusa.com/viewproduct...tnumber=570611

[Unclenick]

You can do that or use your caliper and a fat spacer as below. It's a little easier to be consistent with the Hornady LNL (nee Stoney Point) gauge because it clamps to the caliper jaw, so you don't have to hold anything in alignment, but this method will get you started.



The short throats are troubling, since I expect they would not accept some commercial ammo. It sounds like the .30-06 chamber would not accpet match ammo loaded with the 175 grain SMK, or even the old M72 military match ammo with the 173 grain bullet. That implies they are not SAAMI spec. To save wear and tear on finish reamers, most manufacturers use a carbide roughing reamer to cut most of the chamber, then let the finishing reamer set the throat. I've wondered if they sometimes miss the finishing reaming step and wind up with no throat. That's why I'd like to scope such a chamber. Whatever the cause, touching the chamber with a properly dimensioned finishing reamer will immediately correct the problem.