BCL 102 chamber length compared to Mag length?
- Thread starter Brianma65
- Start date
because of to much jump?
https://www.canadiangunnutz.com/for...uning-for-BCL-102-2-at-250yds-100yds-and-DONE
I believe this will give you your answers.
I believe this will give you your answers.
The leade can change from rifle to rifle in the same run. If you are piecing the rifle together yourself you can control what that is and taylor it to whatever you want to hand load. Either way, if you are handloading for an off the rack or a custom rifle, the stonepoint gauge should be part of your tool kit.
So if limited by magazine OAL, what would be an ideal leade?
For example, my .223 mags are 2.260, what would be the optimum Chamber length?
What would be an ideal jump for the 308?
Just like to add, I’m new at this , I’m going to have a smith help me with this, but his experience is with bolt guns.
Edited**
Freebore, is the term I’m looking for,I think.
So am I right that I need a barrel with a match chamber?
Or a blank,and have a smith ream me a tight chamber, ?
Last edited:
Ok a couple of things I should clarify:
When I say ‘leade’, I’m referring to the amount of room that is left between the ogive of a chambered rounds bullet to the end of the leade (or otherwise the start of the rifling proper) of the barrel. Often referred to (and likely more correct) as free bore.
Leade should properly be defined as the area and distance between the throat and the rifling of the bore (which is the angle cut from throat to the start of the bore proper).
The distance from the end of the chamber to the beginning of the leade is known (or at least I’m referring to in this thread) as the throat.
I’m spelling it out so as to explain what I’m talking about to anyone else reading this, because there is often different terminology thrown about with respect to all of these terms and measurements) but I think you and I Brian, are on the same page (or at least I hope so).
The short answer your question is I don’t know. I’ve read that 1/4” is pretty standard and I know some benchresters and maybe others play with throat depths when they are getting their chambers cut, but they are doing it for very specific loads and reasoning. I wouldn’t do that with an auto loader.
I can say that on measuring my SR-25 I have the following data:
Case gauge is 2.015”
OAL of case and 175gr. Berger OTM to leade: 2.955”
I can load the Berger OTM to a max. OAL of 2.895” so that it fits the magazine.
The ‘leade’ or freebore with this combination is 0.06”
For my Sako TRG-22:
OAL of same round to leade: 2.955”
OAL of round for mag loading: 2.915”
Leade with max. Loaded length for mag: 0.04”
Using the comparator that measures the OAL of the round to the ogive gives me 2.291”
Which in turn gives me throat length (including the angled leade area between the throat and rifling of the bore) of 0.276”.
When I say ‘leade’, I’m referring to the amount of room that is left between the ogive of a chambered rounds bullet to the end of the leade (or otherwise the start of the rifling proper) of the barrel. Often referred to (and likely more correct) as free bore.
Leade should properly be defined as the area and distance between the throat and the rifling of the bore (which is the angle cut from throat to the start of the bore proper).
The distance from the end of the chamber to the beginning of the leade is known (or at least I’m referring to in this thread) as the throat.
I’m spelling it out so as to explain what I’m talking about to anyone else reading this, because there is often different terminology thrown about with respect to all of these terms and measurements) but I think you and I Brian, are on the same page (or at least I hope so).
The short answer your question is I don’t know. I’ve read that 1/4” is pretty standard and I know some benchresters and maybe others play with throat depths when they are getting their chambers cut, but they are doing it for very specific loads and reasoning. I wouldn’t do that with an auto loader.
I can say that on measuring my SR-25 I have the following data:
Case gauge is 2.015”
OAL of case and 175gr. Berger OTM to leade: 2.955”
I can load the Berger OTM to a max. OAL of 2.895” so that it fits the magazine.
The ‘leade’ or freebore with this combination is 0.06”
For my Sako TRG-22:
OAL of same round to leade: 2.955”
OAL of round for mag loading: 2.915”
Leade with max. Loaded length for mag: 0.04”
Using the comparator that measures the OAL of the round to the ogive gives me 2.291”
Which in turn gives me throat length (including the angled leade area between the throat and rifling of the bore) of 0.276”.
Last edited:
Thanks,that’s what I’m talking about.
I’d like to set up my rifle ,as tight as possible,with the least amount of jump. That keeps it safe..
So I’m thinking I’ll need a AR10 smith, or can I order what I’m looking for.
How accurate is your SR25?
That seems like a lot of jump, or is that the standard for an AR10
Last edited:
The SR-25 uses what I believe to be a 20” Krieger heavy profile barrel, and the TRG-22 is a 26” hammer forged heavy barrel.
Both shoot sub-moa. The TRG shoots pretty much anything exceptionally well which makes load development kinda frustrating.
I don’t have mine yet, but when I do I plan to thoroughly wring out the 102 to see how it does.
If I was looking to replace a barrel on it, I’d look to krieger. I think Jerry @ Mystic can get them.
Other local to Canada barrel makers could probably offer close to matching Krieger’s quality and accuracy.
I know some guys like to drill down on jump, but honestly I think it matters a lot less than some would believe.
Now let’s take a step back and think about what it is we are trying to achieve: it’s about consistency. We are taking a round built of different components and we are putting them together. We want all of those components to be the same as much as possible. Same size, weight, and because we are setting a circular item in a circular bore and sending it down range with a twisting, circular path we want concentricity of all of those to be on the same axis as much as possible.
No question, you want to know what the dimensions are in relation to where the bullet ogive is to ensure you are not jamming into the lands upon loading, but as far as whether .04 or .06 makes a difference of how well that prints on paper?
I’ve experimented with the jump with a few rifles including the TRG and I have some skepticism.
Perhaps this is something benchresters do and so that must mean it transfers over to other shooting, I don’t know.
I think concentricity of brass, full length sized brass, seating of the bullet and crimping if that is done, and finally the sending of the bullet through the bore all on the same axis is imperative, and while theoretically plausible, perhaps in all practicality almost impossible to achieve on a consistent basis - but it’s something we all want to strive for.
I think that bullet concentricity as it enters the bore, either through the act of firing or by being jambed into the lands through mechanical means by the bolt) is probably equally plausible.
Both shoot sub-moa. The TRG shoots pretty much anything exceptionally well which makes load development kinda frustrating.
I don’t have mine yet, but when I do I plan to thoroughly wring out the 102 to see how it does.
If I was looking to replace a barrel on it, I’d look to krieger. I think Jerry @ Mystic can get them.
Other local to Canada barrel makers could probably offer close to matching Krieger’s quality and accuracy.
I know some guys like to drill down on jump, but honestly I think it matters a lot less than some would believe.
Now let’s take a step back and think about what it is we are trying to achieve: it’s about consistency. We are taking a round built of different components and we are putting them together. We want all of those components to be the same as much as possible. Same size, weight, and because we are setting a circular item in a circular bore and sending it down range with a twisting, circular path we want concentricity of all of those to be on the same axis as much as possible.
No question, you want to know what the dimensions are in relation to where the bullet ogive is to ensure you are not jamming into the lands upon loading, but as far as whether .04 or .06 makes a difference of how well that prints on paper?
I’ve experimented with the jump with a few rifles including the TRG and I have some skepticism.
Perhaps this is something benchresters do and so that must mean it transfers over to other shooting, I don’t know.
I think concentricity of brass, full length sized brass, seating of the bullet and crimping if that is done, and finally the sending of the bullet through the bore all on the same axis is imperative, and while theoretically plausible, perhaps in all practicality almost impossible to achieve on a consistent basis - but it’s something we all want to strive for.
I think that bullet concentricity as it enters the bore, either through the act of firing or by being jambed into the lands through mechanical means by the bolt) is probably equally plausible.
