.020 from lands puts the bullet too far out? 308 rem 700p

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Kryogen

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Hi, i made some measurements tonight.

Lets take the hornady 168 bthp as an example.
Hdy lists an oal of 2.800
To hit the lands, i need an oal of 2.934
That is 134 mils out. The bullet is only holding in the case by 150 mils or so. With a 20 mils jump that is still approx only 170 mils in the case giving an oal of approx 2.914

Opinions? Does that make sense? I have always followed oem OAL so far.
I single load all match rounds anyway so mag feed is a non issue.
(I used the hdy kit and will use the bullet comparator for precise seating using oal for questions seems easier for all to understand)

Also, has anyone noticed a precision imcrease with a shorter jump? I have a 134 mils jump and the rifle shoots half moa on average.
 
I had mine back just off the lands and then found out that the bullets were too long to fit in my internal mag. I was forced to reduce it to 2.800 (but my lands were at 2.880). To be honest though I didn't see a change in my rifle groups. I did however see the group change when I was tweaking my powder load.

(rem 700 5r milspec rifle)
 
The P has a really long throat, even 178 hpbt's only seat about 150 thou with my rifle. I've heard 190 smk are a good bullet in the .308 700p for seating out go the lands. For 168 I seat to 2.8 and they shoot great.
 
Is it wrong if i load those with just .150 in the neck?

According to litz the 700p twist will not stabilize bullets heavier than the 175 smk so i bought some 175 smk for lr this summer.
 
Today's rifles have longer throats, there has to be enough room in the chamber for the cartridge and the company lawyer.
My Savage .223 with a 1 in 9 twist has a longer throat than my AR15 rifles do.
 
So should I really keep it with .300 in the mouth and not bother with jump, or is it safe for benchrest rounds to load with only 150 in?

Maybe I should run a quickload to see the impact also?
 
The seating depth rule of one bullet dia is arbitrary - you can certainly go less, assuming the bullet is held securely. Personally, the "get close to the lands thing" is a least variable for my rifles. Why don't you try both COALs and report back?
 
Even then.... I screwed up some of my cases during a cycle of reloading and I could twist the bullet out by hand. This cause different OAL in transport. I didn't see any real difference between 100-500 meters. My rifle setup will do 1000 yards, I just can't recall if I used that loosely seated ammo or not.

But yes, rule of thumb, it you push the tip on something hard and it doesn't slide back into the case then you should be good to go.

Did you confirm if you can still load your mag with that OAL?
 
The throat on my 700 SPS AACSD is too long for me to jump the lands with 168 or 178gr pills. If I did so, the bullet would be halfway up (or less) the neck of the case.

I've had good success with regular COAL lengths so I stopped trying to squeeze any more accuracy out of a factory barrel. When I eventually rebarrel it with a premium one, I'll go back to playing with OGIVE lengths.
 
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ok well I have loaded 20 hdy 168 bthp rounds at 2.8 and 15 rounds at 20 mils jump. will report once I have a chance to shoot.
Aint looking good, we got a foot of snow and it's -18 tonight....

as for the 175 TMK, I am waiting for my repaired FL .336 die from forster to use my new lapua batch of brass with the new bullets... one way or the other, it looks like shooting outside is kind of out of the question for another month or so.

What I really enjoy during spring is that temp is warm, and there are no insects.
During summer it gets really hard to shoot outside with the insects... have to wear long clothes, gloves, boots, and I even shot once with a net because there were so many flies eating me alive I couldnt shoot. And guess what, a sucker bit me on the hand.... this summer I'll wear gloves.
 
Kryogen said:
Hi, i made some measurements tonight.

Lets take the hornady 168 bthp as an example.
Hdy lists an oal of 2.800
To hit the lands, i need an oal of 2.934
That is 134 mils out. The bullet is only holding in the case by 150 mils or so. With a 20 mils jump that is still approx only 170 mils in the case giving an oal of approx 2.914

Opinions? Does that make sense? I have always followed oem OAL so far.
I single load all match rounds anyway so mag feed is a non issue.
(I used the hdy kit and will use the bullet comparator for precise seating using oal for questions seems easier for all to understand)

Also, has anyone noticed a precision imcrease with a shorter jump? I have a 134 mils jump and the rifle shoots half moa on average.
Click to expand...

My Rem 700 has a very long throat as well. I just measure to fit in the mag box and develop loads off that. When I find a decent load, I'll see if 2.80 is a better COAL and move around that length. Not much else you can do! They still seem to shoot well. I have a few loads that are MOA or better.
 
They seem fine at around 2.930 for single feed.... Will report once i have had time to try. Bullet is solid in.
Its single feed match ammo anyway.

If it shoots the same at this oal and 2.8 i will just keep it at 2.8, or try somewhere around max mag length as mag fed ammo...
 
I would also try 10 rounds that are touching the rifling. I have a 218 Bee that I am loading long. I have calculated the measurements using a 50 gr Hornady sx and I have approximately .110 in the case. The rifle is a singleshot so I don't have a mag length to worry about. At .015 from the rifling it will have a kinda round group of about 3/4 to 1 inch. When the bullets are touching the rifling, the group has a lot of vertical but quite tight left to right. This tells me I have a bunch of load development to do.

I wouldn't be afraid to go longer with your bullets. Since you single load yours, mag length doesn't matter. As long as your OAL doesn't change between your reloading bench and the shooting bench. As long as you can extract a fully chambered bullet without leaving the bullet in the rifling and spilling powder every where, you should be good to go.
 
I've been working on my load for my 5R 308 for about a year now. Many many trips to the range. Preped the brass to no end. I did the powder thing. different kinds, different amounts, different bullets, different weights. Now working on OAL. I single feed. No way in hell can I put them in the mag.
I don't know what I'll do once "I think" I figured it out??? lol
 
A few points to consider... if the bullet will fully engrave into the lands BEFORE leaving the case neck and has enough shank in the case neck for solid support, chances of decent accuracy is very high.

if the bullet will leave the neck or have very little in the neck, accuracy will be poor.

The distance FROM the lands when loaded doesn't matter (you load tune for that). I would strongly recommend the Hrn 178gr Amax. This solved the throat length issue for one of my customers and could still be loaded to mag length.

If single feeding, I would move to a heavier bullet like the Berger 210gr VLD, 215H, 200H, Sierra 190, 200, 220gr MK, Hrn 195, and heavier. Assuming you have a 10 twist barrel?

If you set the powder charge at one level and move the OAL, you are also load tuning... manually. So don't assume that 1 OAL is better or worst from 1 test. if the barrel will shoot a particular bullet, you can reach the same mechanical accuracy limit with either powder and/or OAL tuning.

I much prefer to adjust the powder charge with a static OAL.

In set ups with high bore wear, you will need to "chase the lands" on occasion and you will know this when well tuned loads start to open up with flyers.

When I find my best load, I will track how the groups change with slight increases and decreases of powder so I can anticipate what the barrel is doing and what I need to do to bring it back into tune.

See my website for load tuning info..... simple and it works.

Jerry
 
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