6.5mm Bullet for the Close Animals

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jbolt
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6.5mm Bullet for the Close Animals

Post by jbolt » Mon Dec 10, 2018 10:03 pm

I picked up a Savage 110 in 6.5 Creedmoor to use as my hunter rifle. I got some Sierra 107 TMK's to try for the close animals but I found out today that the cylinder area of the bullet is shorter that the freebore of the chamber. The case never expands enough to seal against the chamber causing blow back and soot to get to the bolt face. Extreme spread and accuracy is awful. Brass is Lapua. The 142 grain Sierra HPBT on the other had shoots brilliantly for a factory barrel.

For those shooting 6.5's, what bullet(s) are you using for the close animals?

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Re: 6.5mm Bullet for the Close Animals

Post by ywltzucanrknrl » Tue Dec 11, 2018 9:13 am

Interesting, I have several 6.5x55's and have shot the 107's out of all of them including the Swedish Mausers with no issues. When I've had issues with brass not sealing it has been because the brass is very work hardened or the load is very light.
I do shoot quite a few 120 Nosler's also and they have been fine. I haven't had much luck with the bullets lighter than the 107's---although some older 100 Hornady's I had shot pretty well. But have to say, I can't remember shooting my 6.5x55's in silhouette, one is an XTC match rifle and the others are hunting and military rifles. The 107's shoot very well in my XTC match rifle which has a SAMMI chamber.
I'm sure your rifle has different specs on the chamber/throat but was just thinking the Swedish Mausers have a very generous chamber/throat/leade and I've haven't had any problems with them and 107's.
The 120 Noslers are accurate and have quite a bit more bearing surface than the 107's.

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Re: 6.5mm Bullet for the Close Animals

Post by Evelio Mc Donald » Tue Dec 11, 2018 10:33 am

Evidently your load is way too light, not enough pressure to fully expand the neck of the case. The 107 should be extremely accurate in the 6.5 Cred. or 6.5x47 Lapua with the right load. The bullet not touching the lands, don't have anything to do with the case neck not expanding enough to seal the gases.
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Re: 6.5mm Bullet for the Close Animals

Post by jbmarshtx » Tue Dec 11, 2018 12:55 pm

I started reloading late in the summer. I shoot a 6.5 creedmoor.

Using 1-2x fired factory Hornady brass and 108 Lapua scenars, I've had really good accuracy. Based on the book, it's not a hot load, but based on conversations with a few other shooters it's hotter than they use. I have 40.5 grains varget behind it, and I'm 0.020 off the lands.

I did not chrono the loads, but they grouped under 1/2 MOA at 200 yards.

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Re: 6.5mm Bullet for the Close Animals

Post by jbolt » Tue Dec 11, 2018 12:58 pm

With the bullet seated to 2.790" as recommended by Sierra the cylinder of the bullet is about .100" into the neck. At this seating depth it is .09" off the lands. Neck tension is .002".

I ran five 5 shot test loads staring a 35.8 gn up to 37 gn of Varget in .3 gn increments. The higher the charge the worse it got.

The 35.8 gn load had the the lowest spread of 27 fps, a standard deviation of 13.8 and an average velocity of 2709. The 37 gn load had a spread of 101 fps, standard deviation of 58.3 and an average velocity of 2733 which was slower on average of the previous load of 36.7 gn.

Based on the diminishing results I'm not sure increasing the load will help with case expansion. So do I try seating them deeper, increasing neck tension, both???

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Re: 6.5mm Bullet for the Close Animals

Post by jbmarshtx » Tue Dec 11, 2018 1:30 pm

jbolt wrote:
Tue Dec 11, 2018 12:58 pm
With the bullet seated to 2.790" as recommended by Sierra the cylinder of the bullet is about .100" into the neck. At this seating depth it is .09" off the lands. Neck tension is .002".

I ran five 5 shot test loads staring a 35.8 gn up to 37 gn of Varget in .3 gn increments. The higher the charge the worse it got.

The 35.8 gn load had the the lowest spread of 27 fps, a standard deviation of 13.8 and an average velocity of 2709. The 37 gn load had a spread of 101 fps, standard deviation of 58.3 and an average velocity of 2733 which was slower on average of the previous load of 36.7 gn.

Based on the diminishing results I'm not sure increasing the load will help with case expansion. So do I try seating them deeper, increasing neck tension, both???
Again, I'm a newbie at reloading. I sent my 1x fired off to get cleaned and full length sized while I got my reloading gear. For my 3rd reload, I used a Whidden die with a 0.289 bushing to size the brass. Neck tension was 0.001-0.002. I didn't clean the necks, just lubed, sized, cleaned the outside.

Were you using new brass that hadn't been sized? Was there any dry lube or carbon in the necks? When I was using 'clean' brass my groups weren't as good. When I was using brass that had some carbon in the neck, they tightened up a bit.

I'd seat them longer, closer to 0.020 off the lands. Again, newbie here.

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Re: 6.5mm Bullet for the Close Animals

Post by Evelio Mc Donald » Tue Dec 11, 2018 3:18 pm

jbolt
Have you check the twist on your barrel ? You need at least an 8 twist to stabilize the lighter bullets. Try the Sierra 123 with 36 or 37 gr. of Varget and use a magnum primer. If you still get blowback with them, then the problem could be an oversize chamber, or you are sizing the neck too much.
You may also want to buy a box of factory ammo. and see what it does, versus hand loads.
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Re: 6.5mm Bullet for the Close Animals

Post by jbolt » Tue Dec 11, 2018 3:20 pm

jbmarshtx wrote:
Tue Dec 11, 2018 1:30 pm

Again, I'm a newbie at reloading. I sent my 1x fired off to get cleaned and full length sized while I got my reloading gear. For my 3rd reload, I used a Whidden die with a 0.289 bushing to size the brass. Neck tension was 0.001-0.002. I didn't clean the necks, just lubed, sized, cleaned the outside.

Were you using new brass that hadn't been sized? Was there any dry lube or carbon in the necks? When I was using 'clean' brass my groups weren't as good. When I was using brass that had some carbon in the neck, they tightened up a bit.

I'd seat them longer, closer to 0.020 off the lands. Again, newbie here.
Well I have been reloading for 40 years and never had this issue before in a rifle cartridge but this is the first cambering I have done which is designed for long high BC bullets.

At .020" off the lands the neck would only be grabbing .030" of the bullet. This is new Lapua brass. I use a mandrel through the neck to set the tension.

I'm theorizing that with the short bearing area between the bullet and neck and the sort bearing cylinder of the bullet, the bullet has moved to the end of the neck and just starting to touch the lands before the case can fully expand.

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Re: 6.5mm Bullet for the Close Animals

Post by jbolt » Tue Dec 11, 2018 3:28 pm

Evelio Mc Donald wrote:
Tue Dec 11, 2018 3:18 pm
jbolt
Have you check the twist on your barrel ? You need at least an 8 twist to stabilize the lighter bullets. Try the Sierra 123 with 36 or 37 gr. of Varget and use a magnum primer. If you still get blowback with them, then the problem could be an oversize chamber, or you are sizing the neck too much.
You may also want to buy a box of factory ammo. and see what it does, versus hand loads.
Evelio.
Yes it is a 1:8 twist and using CCI 450 primers. Neck tension is the same for the 142's. The Sierra 142 HPBT's with 35.4 gn of Varget have a spread of 1 fps, standard deviation of 0.6 with no blow back. Overlapping groups at 100 yds with me behind a factory 3 lb trigger so the longer bullet is working about as good as it gets.

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Re: 6.5mm Bullet for the Close Animals

Post by ywltzucanrknrl » Tue Dec 11, 2018 4:06 pm

I think your idea of seating them deeper and increasing neck tension is a good bet. I would also try a standard primer--based on this---standard small rifle primers in a 22 Hornet can dislodge the bullet before the powder burns and cause erratic accuracy, high ES and SD---some folks solve this by using small pistol primers that are more mild and using higher neck tension or a crimp.
Although I like CCI 450's for my AR service rifle because they have thick hard cups, they have caused me similar problems with long seated VLD's---switching to standard R-P small rifle primers solved the SD and ES problems---oranges to apples though as gas guns vs bolt guns.

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Re: 6.5mm Bullet for the Close Animals

Post by Another Dang 9 » Tue Dec 11, 2018 5:34 pm

If you haven't made a chamber cast now would be a good time to do it. Its best to start with that and eliminate that as an issue first. Then you can do experiments with loads if the chamber meets sammi specks. You can do it yourself with products like Repro-Rubber or similar products for a few bucks.
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Re: 6.5mm Bullet for the Close Animals

Post by dwostler » Tue Dec 11, 2018 7:59 pm

Have you tried a normal seating depth and a faster powder for the lighter bullets.
Like Benchmark or H-322, I think it is the timing of your pressure spike.
A faster powder will help seal the case mouth a little sooner than Varget.
107's or 108's should work fine.
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Re: 6.5mm Bullet for the Close Animals

Post by jbolt » Tue Dec 11, 2018 8:49 pm

dwostler wrote:
Tue Dec 11, 2018 7:59 pm
Have you tried a normal seating depth and a faster powder for the lighter bullets.
Like Benchmark or H-322, I think it is the timing of your pressure spike.
A faster powder will help seal the case mouth a little sooner than Varget.
107's or 108's should work fine.
Dennis
Bullets are seated to Sierras recommended COAL. I have some Benchmark so I will give that a try.

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Re: 6.5mm Bullet for the Close Animals

Post by plzbry » Tue Dec 11, 2018 10:54 pm

Looked at Hodgens reloading data it recommends starting at 37 grains of varget with 107s up to 41.go to low and things go kaboom

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Re: 6.5mm Bullet for the Close Animals

Post by Jason » Wed Dec 12, 2018 9:34 am

Sierra's recommendation is only that, a recommendation. It should work in most rifles with most brass, but not necessarily all the time. It sounds like you have a generous chamber on the factory rifle with new(ish) Lapua brass that is likely designed with expectations of very tight custom chambers and trimmed to minimum spec length. What is the COL with the Lapua brass?

With only 0.002" of neck tension, only having 0.1" of the bullet gripped by the neck seems sure to not provide enough grip on the bullet to let pressures increase before the bullet leaves the case. Since it also has room to move fairly far before it touches the lands, you're going to get inconsistent accuracy as that bullet wiggles around in the chamber before it gets pushed into the lands. You're also using magnum primers which are going to exacerbate pushing the bullet out of the case before there's enough powder burning to have pressure built up, although they're small rifle magnums so that shouldn't be a problem if you get proper grip on the bullet. You shouldn't need to change powder. Varget isn't very difficult to ignite and is plenty fast to use those 107 grain bullets. Just seat the bullet deeper.

How much is your brass growing when being fired with the heavier bullets? You may want to have all of your brass have an initial firing with the heavier bullet to fully expand it. You'll get a bit extra length if you full length size it, and then don't trim it back too far. That might let you get closer to the lands and still have good grip on the bullet to get ignition before it leaves the case. You'll need to find a way to do that consistently across all the brass to get good accuracy, of course.

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