Why do rifles love/hate a bullet?

Slowbalt

Slowbalt

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Doing some load development for a .308, been trying Campro 147gr FMJ hoping I could find a nice cheap load, but so far that gun HATES it. Will not group better than two inches at 50. Same rifle does under a half inch at the same distance with 180gr Accubond.

Why does one rifle "like" a bullet, but not an other? Other than the weight/length of course. Thickness of the jacket? Metallurgy of the same? Voodoo magic? Or is it mostly about consistency?


(FYI, rifle is a Tikka, chambered in 308, 20in barrel and 1 in 11 twist)
 
Hornady, Sierra, Nosler etc. premium quality bullets are manufactured to exacting tolerances and a high standard of quality control and materials than the plinker grade, hence the difference in accuracy, and price.
 
Yes. A cheap plinker bullet.

As a rule of thumb, any bullet that is open at the base will shoot poorly compared to any bullet open at the nose.

If you want "cheap" and "accurate" by the flat base soft points. Hornady are excellent.
 
Slowbalt said:
Or is it mostly about consistency?
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Assuming that your gun has the appropriate twist rate & freebore....Bullets -like all the other components especially brass -it all comes down to consistency.

I systematically sort all my competition projectiles by bearing surface length in half thousand increments.
With quality bullets such as Sierra and Bergers, I usually see a general extreme spread of 0.003 to 0.004 in this measurement.

Once in a while I come across one or two in a batch of 500 where the BSL is around 0.010 different than the extreme high or low.
These are used as foulers only.

If you have 2 Hornady bullet comparators, then put them both on the jaws of your calipers.

Re-zero your calipers and sort your remaining pile of Campros .... you might have a lot variance in your bearing surface lengths.

Now that you have sorted them into mini batches.... your groups might shrink.
 
An Anschutz 1840E commercial Mauser in 308 that hated any bullet under 190grs. It was around 1 in 10. Does well at 200+
 
Slowbalt said:
Doing some load development for a .308, been trying Campro 147gr FMJ hoping I could find a nice cheap load, but so far that gun HATES it. Will not group better than two inches at 50. Same rifle does under a half inch at the same distance with 180gr Accubond.

Why does one rifle "like" a bullet, but not an other? Other than the weight/length of course. Thickness of the jacket? Metallurgy of the same? Voodoo magic? Or is it mostly about consistency?


(FYI, rifle is a Tikka, chambered in 308, 20in barrel and 1 in 11 twist)
Click to expand...

I have not found the rifle that will do better than 2.5 - 3 moa with the 147 FM Campro. It's a plinker bullet, and not worth wasting too much time on for load development.
 
Ganderite said:
Yes. A cheap plinker bullet.

As a rule of thumb, any bullet that is open at the base will shoot poorly compared to any bullet open at the nose.

If you want "cheap" and "accurate" by the flat base soft points. Hornady are excellent.
Click to expand...

I get excellent performance (accuracy and terminal) with cheap old Hornady 50 and 55 SPSX. 50 SPSX out of a .222 Rem. is my all time favorite.
 
I'm the odd one out I guess with the 147gr cam pro, my k31 will do an inch or less at 100 yds if I do my part, pushing them quite slow though, only around 2250fps
 
The 147gr bullet may just too light to be properly spun up in that barrel's twist. I've seen it happen in other calibre/twist combinations, that light bullets went all over but anything heavy enough was shooting wonderfully.
 
Slowbalt said:
Doing some load development for a .308, been trying Campro 147gr FMJ hoping I could find a nice cheap load, but so far that gun HATES it. Will not group better than two inches at 50. Same rifle does under a half inch at the same distance with 180gr Accubond.

Why does one rifle "like" a bullet, but not an other? Other than the weight/length of course. Thickness of the jacket? Metallurgy of the same? Voodoo magic? Or is it mostly about consistency?


(FYI, rifle is a Tikka, chambered in 308, 20in barrel and 1 in 11 twist)
Click to expand...

Maybe the twist likes the heavier bullets.
 
jethunter said:
I have not found the rifle that will do better than 2.5 - 3 moa with the 147 FM Campro. It's a plinker bullet, and not worth wasting too much time on for load development.
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My very latest outing (this morning) tends to confirm that theory... So cheap though... Think I may be better off with some good cast bullets *wink-wink*
 
Slowbalt said:
My very latest outing (this morning) tends to confirm that theory... So cheap though... Think I may be better off with some good cast bullets *wink-wink*
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Try Berry Bullets 150grn FN for the 30/30, Load them under 2000 FPS. I know I'm using them in my 308, loaded with pistol powder and pulled off a around 1/2" group ( Cannot confirm if it was 4 or 5 shot group ) at 100M
 
I get great results with those Berry's and unique in a '94 carbine and the SPX.
As far as 'pricey' pills go I bought some of the polymer tip Hornady for lever guns and couldn't get them to group, stopped trying and they just collect dust now - in hindsight they weren't a smart buy to begin with.
 
OkayShooter said:
Try Berry Bullets 150grn FN for the 30/30, Load them under 2000 FPS. I know I'm using them in my 308, loaded with pistol powder and pulled off a around 1/2" group ( Cannot confirm if it was 4 or 5 shot group ) at 100M
Click to expand...

TargetAcquired said:
I get great results with those Berry's and unique in a '94 carbine and the SPX.
As far as 'pricey' pills go I bought some of the polymer tip Hornady for lever guns and couldn't get them to group, stopped trying and they just collect dust now - in hindsight they weren't a smart buy to begin with.
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Any source for these? Remember Henry at BSS used to carry them, can't find them anymore. Willing to give them a try before going to cast as the no-exposed lead is so convenient.
 
Those are the first boat tail bullets I've seen with exposed lead bases.

Being that they're CamPro bullets, I would think it has more to do with uneven jacket thicknesses around the circumfrence.

I've even had CamPro bullets that weren't concentric to their axis, up to .015 run out on the tip of the bullet from the base center.

My reasoning for this is that I have a bunch of FMJ 6.5 x 160 grain roundnose, cupronickel jacketed bullets with exposed lead bases. When they were cheaper than dirt, I picked up 5000 of them.

They were great for 6.5 caliber rifles with worn or oversize bores. No, they aren't tack drivers but they shoot very consistent groups around 2 moa, right out to 500 yds, if I do my job on the other end.

I still have a few hundred .314 diameter FMJ flat base bullets with exposed lead cores. I bought them for the same reason, they were cheaper than dirt. I seem to remember 10K. They shot well, no matter which rifle the cartridges were loaded in.

All different marks of Lee Metfords/Enfields were notorious for varying bore diameters, from one rifle to the next. Especially those with wartime production barrels with relatively loose standards.

I've had similar issue with 1903 Springfields and P17 Enfields.

Most commercial bores have been very good for the last 30 years.

What happens with the exposed lead cores, is that when the cartridge is fired, the pressure pushing the bullet, forces the lead into the cavity, in turn forcing the jackets to completely fill the grooves and maintain an acceptable level of accuracy.

The other reason being that it was just easier to build/swage the bullets during manufacture.
 
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