7mm-08: Multi-Q

[depoloni]

Found a fairly accurate load in my then-new TC Pro Hunter 7mm-08 last year - worked up loads with several powders including Varget, H-4895, and H-4350 with a number of "normal" bullets (don't do premium) and found that the most accurate load was:

47.5 grains H-4350 pushing a 140gr Sierra SP flat base, avg. 2860fps
---remember this is a 28" barrel, not a max load either

This load was worked up at the book-listed OAL of 2.800".

Checked that rifle recently for freebore and found that in order to "touch the lands" with that 140 Sierra I have an OAL of 2.925"... that 1/8" jump into the lands seems like a lot for me despite the 1.5MOA accuracy already given.

I think this rifle has a lot more, it's a 1:9 twist so it should spin anything up to 175 grains well (no?) and I'm curious what you all think given the above information:

1) Best next-step to take the 140 Sierra load and try OAL's of 2.840, 2.880, and 2.900 to reduce that "huge" (?) jump into the lands? One thing I'm worried about is that this bullet has barely a half-caliber IN the neck at the longer OALs. That cool?

2) Best next-step to take the load for what it is and try something heavier (thus longer) like a 150gr or 160gr bullet? That would automatically seat it closer to the lands while also keeping more in the neck.

Hope I provided enough info but let me know what you think. I'm mostly curious whether playing around with the 140-class OAL, versus moving up in bullet weight, will likely lead me (if it will?) to more accuracy. As it is now the thing is a "hunter" with the big-jumping load above, so it's not the end of the world.

thanks!

 

[Ol` Joe]

Keep a caliber worth of bullet in the neck with hunting loads. The neck tension, and concentricity of your ammo can start to go downhill with short seating.

"Loading to the lands" is`nt the last word in accuracy. There are normally more then one sweet spot if you play with seating, and both can be quite far back from the throat. Weatherby is known for their long leads (most run about 3/4") and most of their rifles are very accurate.

If I was looking for a more accurate load I`d switch bullets. H4350 and the Sierra 140 is a accurate load in my 708 too, but the Nosler 120 gr BT with IMR4007sc drives tacks. (Varget works well with them too) The little Nosler has a 140 gr jacket and is excellent for deer from what I`ve been told.

The 139 gr Hornady SP is another good bullet. The ogive is long on them though, and you won`t get them nearly as close to the lead as a Sierra or Speer. Again, that isn`t always a bad thing and you might find they shoot very well for you with some experimenting.

 

[ants]

Why do we reload, if we don't experiment?

Try loading your 140g out to 2.905 (20 thousandths off the lands) just to see if accuracy improves. I doubt it, the groups will probably be identical to your existing load. But what do you have to lose? You lose 5 bullets? And you gain knowledge about your rifle.

Also, experiment with 160 if you want. I happen to like the flatter trajectory of 140. Upon impacting a deer, there is probably little difference between 140 and 160. But what do you lose by experimenting?

I say experiment. Find out what your TC will do.

 

[jmorris]

This load was worked up at the book-listed OAL of 2.800".

Checked that rifle recently for freebore and found that in order to "touch the lands" with that 140 Sierra I have an OAL of 2.925"... that 1/8" jump into the lands seems like a lot for me despite the 1.5MOA accuracy already given.

I think this rifle has a lot more, it's a 1:9 twist so it should spin anything up to 175 grains well (no?) and I'm curious what you all think given the above information:

Reducing the amount of free boar has not always shown me improvements in accuracy, but it’s worth a try. Just remember to back your load off because eliminating that “jump” (AKA running start) into the rifling will increase the pressure.
I know H-4350 is slower than IMR 4350 but I bet your approaching the high end (and would already be over with IMR 4350). No kabooms is the first ingredient in a good day.

 

[depoloni]

Thanks Gents!

So far, great suggestions. Much appreciated.

I got a blemished bulk-box of 139 hornadys from Midway that I should give a try. Bought them, then shied away, because I heard they were one of the most likely bullets to explode at short range even compared to 140 Sierra "softies". Don't worry, won't be an accuracy problem as I sorted them by weight to remove any that had some sort of hollow cavity rather than just some surface discoloration. The sorted ones should be as good as factory firsts, and I'll try 'em and let you know.

You feel the 120 is "enough bullet" for beefy michigan whitetails? Assumed, not sure, that it was a bit on the light side.

I'm going to try the 139 hornadys and the 150's first, then we'll check with 120's and 160's. I'll post up here what I find over the coming weeks. Or months lol

 

[Ol` Joe]

I got a blemished bulk-box of 139 hornadys from Midway that I should give a try. Bought them, then shied away, because I heard they were one of the most likely bullets to explode at short range even compared to 140 Sierra "softies".

I`ve use this bullet (139 gr SP, NOT the SST) on Michigan deer with excellent results. Total pass through has been the result, although I have to admit I`ve only shot 2 deer with it. Both though were within 30 yds and the velocity was in the 2750+ range at impact and shoulder bone was hit in one case.

I haven`t used the 120 Nosler Ballistic tip on deer. I`ve switched to the 260 Rem for my go to rifle the last 7-8 years, but I have heard too may others talk them up to believe they are soft. I do shoot them, and have found them to be a extremely accurate bullet. I run them at ~ 3000 fps with IMR4007 and sub MOA from a 24" BBL`ed 7-08.

Nosler uses the same jackets on them, they use on their 140 gr, and I`ve heard people talk of very good results with them on game up to caribou in size. I wouldn`t hesitate to try them on deer if useing a 708, 7x57, 280, ect.

You might want to ask about them on the Nosler forum and see what others think
http://www.noslerreloading.com/phpBB2/

 

[depoloni]

Thanks Joe.

 

[langenc]

Those blemed Hornadys wont explode. What do they look like? The blems I have (wish I had MORE) were discolored, cannulures not consistantly placed. No malformed bullets.

One batch of 25s were excellent. Weights were very consistant.

 

[depoloni]

The blems I've gotten from midwayusa.com have always been perfectly fine from what I can tell - of the 200 139's I bought not one had worse than some brownish discoloration. Only two bullets out of those 200 were off by more than .4 grain, both at 139.7... the rest were 138.6-139.4 easily. They're the typical SPBT hornadys, the cannelures weren't off at all from what I could tell either.

I got a box of 150-grain flat bases that are either Prvi or pulled rem/win bullets - can't tell if I've got a thin second cannelure or if it's a miraculously consistent and even collet mark from a bullet puller. They shoot pretty good too out of my T/C.

I played around today with the loads, and found that by moving the 140 Sierras out further so that the ogive was about .008" off the lands, the groups dropped from ~1.5 MOA down to two 3-shot groups of just over 0.5 MOA today. Pleased. Surprised, but pleased. At 0.5 MOA with 140 Sierras, unless I feel I need a tougher bullet someday I'm NOT messing with that. Good learning experience, will have to see if changing the "bullet jump" in my other calibers has as pronounced an effect.

I should also add that the last box of 165 grain SPBT "blemished" 30-cal bullets were absolutely unblemished. Must have been factory extras. All tips, cannelures, weights, and even the color of the copper was brand spanking new! I'm hopping all over those any chance I get when they go on sale.

 

[MMCSRET]

My 7-08 is a custom, done on an Oberndorf intermediate length action, but it shoots 3 shot cloverleafs @ 100m. using cheap 140 gr. Remington corlok'ts over IMR4895 in assorted cases. Easily the least finicky rifle I own. Using standard primers and a $30.00 4x scope.(gottchangethatsomeday)