PRC bullet seating depth

B

blackfoot95

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Joined
Sep 18, 2024
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14
Location
Colorado
I'm getting ready to work up a load for a 7mm PRC. normally I'd measure the distance to lands and adjust accordingly but being that the PRC cartridges are designed to have extremely precise chambers I'm considering just using the C.O.A.L. given by the manual. What have ya'll been doing?
 
there's nothing more precise about that chamber than any other chamber.
I load a bullet in a case with a bit of lube on it and slam it into the rifling which pushes the bullet back into the case. I take .030" off this measurement and compare it to the max length my magazine can take then I load to which ever length is shorter and go from there.
 
blackfoot95 said:
I'm getting ready to work up a load for a 7mm PRC. normally I'd measure the distance to lands and adjust accordingly but being that the PRC cartridges are designed to have extremely precise chambers I'm considering just using the C.O.A.L. given by the manual. What have ya'll been doing?
Click to expand...
As with anything else, YMMV. I prefer loading CBTO to the lands regardless of chambering.
charlie 7 said:
How would you do it?
Click to expand...
 
get the hornady OAL gauge and the 7PRC case for the gauge. it is the most accurate, repeatable and easiest way to get the base to ogive, coal etc.

i am currently working on the new Barnes LRX 160. Barnes' guide says 3.325 coal, talked to Barnes they said the LRX likes a lot of jump. For my chamber 3.325 is .26 jump. That is a lot of jump! I tested 3.325, 3.335, 3.350, 3.375 and 3.4. 3.4 was the best by a considerable margin. That's .185 of jump, still quite a lot. Point being my throat is probably longer than the barrels Barnes is using, every barrel will be different. That's why you need to measure and adapt to your barrel.
 
Very nice of you FEENIX to enlighten me on the subject.

But the question was directed at blackfoot95 to tell us the method he uses and how he does it, as there are several.
Knowing his method we can avoid giving him repeated advice of his method. And in the process we could see the level of his expertise, so any advice given could be appropriate to that level.
 
I was mostly interested in finding out if anyone was eliminating this step with PRC cartridges as the literature I've read states the specifications for the PRC cartridges are much more stringent than standard cartridges which if maintained would mean all ammo could be safely produced at one "custom" length.
As for my method I've always used a cleaning rod to measure to the bolt face then push a bullet into the bore for the 2nd measurement. Subtract. 020" off the measurement then double check by chambering a bullet colored with a sharpie to ensure the bullet isn't touching.
 
blackfoot95 said:
I'm getting ready to work up a load for a 7mm PRC. normally I'd measure the distance to lands and adjust accordingly but being that the PRC cartridges are designed to have extremely precise chambers I'm considering just using the C.O.A.L. given by the manual. What have ya'll been doing?
Click to expand...
I find the lands and start from there. Then in seating depth testing, I back off in .010" increments for coarse testing, and .003" for fine testing if needed.

I never go by what any book tells me is COAL. Way too many variables, and I highly doubt any of those are close to the lands to start with.

I pull my bolts apart and use the "unhindered bolt fall" method myself.

As for the literature stating "the PRC specs are much more stringent", that is hype from Hornady. There is still a SAAMI spec. It is no more or less stringent than any other cartridge. Especially when the best reamer design for the 7PRC is the 7PRC AW reamer...
 
whatever length you land on, make sure they function well out of your magazine.

TOO MANY get caught up in all the Minutia when searching for a load.

IF, you are going for F-Cass accuracy, then, yes, waste the components chasing that MAGIC load.

IMO, most hunters' rifles are incapable of supreme accuracy either this or the shooter is a flinch machine and just can't shoot accurately.

"The unhindered bolt fall". Somebody's watching too many YouTube videos. This is a fine method for the Eric Cortinas and Speedy Gonzalez's of the world, but average Sam deer hunter is just wasting ammo. You have a cartridge with too long OAL, you're setting yourself to fail. Someone above says he JAMS his bullets into the lands. Jesus, another hunting load fail. This is an old benchrest trick. If these benchresters have to open their bolt for some reason, the bullet sticks in the lands and you have a receiver full of 8208. (gunpowder for some of you).

I'm old and have been up and down all those rabbit holes all my life. Now, I've come full circle. I shoot a custom lightweight rifle using Premium Factory loads. 130gr. Federal Terminal Accent. no problem getting .75MOA, Swarovski BDC is set to 400 yards and confirmed at ranges to 400 yards.

carry-on
 
charlie 7 said:
Very nice of you FEENIX to enlighten me on the subject.

But the question was directed at blackfoot95 to tell us the method he uses and how he does it, as there are several.
Knowing his method we can avoid giving him repeated advice of his method. And in the process we could see the level of his expertise, so any advice given could be appropriate to that level.
Click to expand...
The OP already noted he used to measure to the lands,
blackfoot95 said:
normally I'd measure the distance to lands and adjust accordingly
Click to expand...
and your question was not definitive if you are asking as to "how-to" and that you are needing the information. If not, my apologies for trying to help out.
 
Buzzsaw said:
whatever length you land on, make sure they function well out of your magazine.

TOO MANY get caught up in all the Minutia when searching for a load.

IF, you are going for F-Cass accuracy, then, yes, waste the components chasing that MAGIC load.

IMO, most hunters' rifles are incapable of supreme accuracy either this or the shooter is a flinch machine and just can't shoot accurately.

"The unhindered bolt fall". Somebody's watching too many YouTube videos. This is a fine method for the Eric Cortinas and Speedy Gonzalez's of the world, but average Sam deer hunter is just wasting ammo. You have a cartridge with too long OAL, you're setting yourself to fail. Someone above says he JAMS his bullets into the lands. Jesus, another hunting load fail. This is an old benchrest trick. If these benchresters have to open their bolt for some reason, the bullet sticks in the lands and you have a receiver full of 8208. (gunpowder for some of you).

I'm old and have been up and down all those rabbit holes all my life. Now, I've come full circle. I shoot a custom lightweight rifle using Premium Factory loads. 130gr. Federal Terminal Accent. no problem getting .75MOA, Swarovski BDC is set to 400 yards and confirmed at ranges to 400 yards.

carry-on
Click to expand...

So the answer is shoot factory ammo. 🤪
 
I would still measure to the lands. I use the Hornady tool. I would see what mag length puts you at. With some rifles and bullets mag length might have you in the lands. Measuring will tell you.
 

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