Cartridge Overall Length differences.

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12 years 5 months ago - 12 years 5 months ago #12163 by Moby
Cartridge Overall Length differences. was created by Moby
I'm looking at the "Accuratepowder.com" load data sheet and I've a question about the information.

The COL (Cartridge overall length) differs depending on the powder/bullet used.
With the rifle chamber constant of course, why the different lengths?

The differences are from 2.720-2.810 for Winchester .308
I'm confused about the load data telling me at times to leave a gap.

When loading and logging different gains/bullet combinations to learn what the rifle likes for "best group" does one vary the COL as well as other variables?
:huh:

page 17
www.accuratepowder.com/wp-content/upload...te_load_data_3.5.pdf
Last edit: 12 years 5 months ago by Moby.

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12 years 5 months ago #12174 by txlongshotb4
Replied by txlongshotb4 on topic Re: Cartridge Overall Length differences.
There are a handful of reasons as to why these specifications vary. Most common are going to be that the actual physical profile of the bullet (projectile) differs from one make/ model to another....Some bullets are simply longer than others. Another reason is the position of the cannelure along the bullet's profile to allow for crimping. Some bullet's COL are determined by space available in the magazine. They can also be spec'ed to optimize the amount of "free-bore" inside of a rifle's chamber.

The good news is, this is not a set-in-stone issue...You can play around with COL to see what works best for your rifle. In my bolt guns, I like to load my rounds long, so that I am actually seating the projectile into the lands and grooves by just a few thousandths when I lock the bolt handle into battery, to eliminate that "jump" the bullet has to make across the free bore section in the chamber to the lands and grooves. I'd shy away from such practices with a semi auto gun however...too much resistance can result in a failure to complete a full cycle.

A quick side note...I've never seen this happen on an AR-10 type rifle, but I've had issues in an M1A with using hand loads that were not crimped into the cases. It seems the inertia from the recoil was enough to slam the rounds in the magazine forward into the housing of the magazine body, and it resulted in forcing the projectiles further into the case mouths than I had set them...not so much to cause any harm, but not so good for consistent accuracy...I'd recommend crimping your rounds into the case necks.
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12 years 5 months ago #12176 by Moby
Replied by Moby on topic Re: Cartridge Overall Length differences.
Once again you've got the expertise I seek. I do have a crimping die for my LEE press. I was told by Gary Sansone that crimping was not needed on a bolt action rifle. Do you agree with that? The reasoning was there was not the "jolting" of the rounds in magazines pre-chambering which could cause the bullet to move in the non crimped casing. Sounded logical to me.

Also, he sold me Accurate 2495 powder. This is where the load data and information came from (Their site). What powder do you use? I am reloading Hornady 168 grain HPBT. Any expeirience with this bullet?

I have a shipment of needed parts for reloading (one of them a digital caliper per your advice) When I get some rounds prepped and trimmed I hope you and your wife might consider coming down for dinner one night and check out my reloading rig.

I'm really looking forward to learning to reload for my AR.

Do you know of ranges in the area that allow FMJ rounds?

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12 years 5 months ago #12180 by txlongshotb4
Replied by txlongshotb4 on topic Re: Cartridge Overall Length differences.
It is not generally necessary to crimp for bolt guns, unless you are shooting one of the big magnums that generate a tremendous amount of recoil, and then it's a good idea just in case. I don't know if you've ever fired a .338 Lapua before, but the recoil that round generates could dislodge your soul, let alone your bullets.

I have not yet delved into reloading for my AR-10. In the past I reloaded match ammo for my bolt guns, and when I did I used Sierra 168 and 175 match kings which are both HPBT bullets. I've also used Berger 175 HPBT's and on a few occasions, I also used some bullets from a company called Lost River Technologies. I don't believe they're in business anymore, but I won't miss em'...they offered some hand turned match grade bullets that were supposed to be the bee's knees, with a hefty price tag to boot. Turns out, they didn't shoot worth a damn...If you ever come across any of these bullets, don't be fooled...They don't seem to work too well, and even if they did, they cannot be replaced because the company is gone.

Anyhow, As far as powder is concerned, I experimented with several different brands, and I came down to three that I seemed to get good results from. Those three were Alliant R-15, IMR 4064, and (the best I found) IMR 4895. If memory serves me correctly, I had settled on 43.7 grains of IMR 4895 behind a Sierra 175 grain MK bullet in my FN SPR A3G, and that was a 1,000 meter gun with that load, all day everyday.

For an AR-10, the recipe is going to be a lot different. I cannot really give you any pointers for load data here because I haven't done it, but I don't think from what I've read here in the past that those powder choices I stated above for bolt guns are favorites for semi-autos.

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12 years 5 months ago #12181 by txlongshotb4
Replied by txlongshotb4 on topic Re: Cartridge Overall Length differences.
Wow...so I was just typing away at another reply to your question, and it just "disappeared"...that was weird.

In response to your question about local ranges that allow FMJ's;

Sadly, I do not know of any others in the immediate area. There used to be a VERY nice place between Burleson and Benbrook called Rock Creek gun range, but unfortunately the land it was sitting on was prime real estate for those big McMansion homes that sell for millions of dollars, and the owners eventually gave in to the lure of the mighty dollar.

I know of a place in Alvarado that has a 500 yard range, but it is not a public range and to use it you have to take course offered by the owner-but said owner is a former Marine Corps special operations sniper school instructor and he teaches a damn good course for a very reasonable rate if you're interested. He is a friend of mine, and I can vouch for his expertise. He also has a 1,000 meter range at another location that is not too far North of here.

There's a place to our East somewhere around Kauffman that has a 1500 yard range, and a place to our North that has an 1800 yard range that both allow FMJ's but you have to become members as they are both private clubs. There is also one out West that has a 1000 yard range, but it is a long drive to get there.

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12 years 5 months ago #12182 by BUILDING MY SASS
Replied by BUILDING MY SASS on topic Re: Cartridge Overall Length differences.

Moby wrote: I'm looking at the "Accuratepowder.com" load data sheet and I've a question about the information.

The COL (Cartridge overall length) differs depending on the powder/bullet used.
With the rifle chamber constant of course, why the different lengths?

The differences are from 2.720-2.810 for Winchester .308
I'm confused about the load data telling me at times to leave a gap.

When loading and logging different gains/bullet combinations to learn what the rifle likes for "best group" does one vary the COL as well as other variables?
:huh:

page 17
www.accuratepowder.com/wp-content/upload...te_load_data_3.5.pdf


I could not open the link you posted...but anyways...I will put in my view...
The Lengths you stated are "MAX" lengths for "BOLT" ACTIONS....in a Semi Auto..you have to keep them around (Case Length)2.0000 give or take a few .0001 depending on how far you go...This was Taught to me by Several EXPERIENCED PEOPLE...MSH being one of them..You may not know him...Go To the Archives....Given the Weight of the Bullet and Type will Depend on Your over all length...Hornady states around 2.7 to 2.75...Again this is "MAX"..length..for bolt actions..you (again) are dealing with a "Semi-Auto"...keep it under 2.7....Mine range in the 2.6 to 2.65...Again Remember it is a SA...so forces will be greater going into the battery and the chamber..over a Bolt Action...Most Manuals are set to BAs...not SA...You have to remember this in Reloading for them...
Again...Just my VIEW and OPINION.....
BMS
For any NRA Reloading Instructors out there, IF I am wrong...Please state your Opinion..
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12 years 5 months ago #12183 by BUILDING MY SASS
Replied by BUILDING MY SASS on topic Re: Cartridge Overall Length differences.
From Your OP...(original Post)...You need to buy a Hard Cover Manual to Start....
and read it three times at least...
Again my Friend...Just my input...
BMS...
If you need some help...Check my Videos...Reloading For Beginners By A Beginner....it may help you to get Started...

www.ar10t.com/index.php?option=com_kunen...1&id=2927&Itemid=270

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12 years 5 months ago - 12 years 5 months ago #12184 by Moby
Replied by Moby on topic Re: Cartridge Overall Length differences.
Funny you mention the hard cover manual. I just watched your youtubes on reloading and am currently looking for the right manual for me. I'll probably go with Hornady as you did. I've so far lubed, de-primed, and resized about 500 cases. I'm waiting on a few items from Midway (and a manual) before moving forward. I've a lot of primer pocket cleaning to do, and I need a brush for inside the case. Your video's helped a good bit. I've also purchased a log book to record everything. My goal is a coffee cup sized group at 400-500 yards. I do not have a match grade barrel so this may be asking a lot, but I want to get as close as I can.

BUILDING MY SASS wrote: From Your OP...(original Post)...You need to buy a Hard Cover Manual to Start....
and read it three times at least...
Again my Friend...Just my input...
BMS...
If you need some help...Check my Videos...Reloading For Beginners By A Beginner....it may help you to get Started...

www.ar10t.com/index.php?option=com_kunen...1&id=2927&Itemid=270

Last edit: 12 years 5 months ago by Moby.

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12 years 5 months ago #12187 by Redscout02
Replied by Redscout02 on topic Re: Cartridge Overall Length differences.
Your asking a lot just because you don't have a match grade barrel. If you can shoot it your loads will do it. Not saying you can't shoot. Just saying the gun will.

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12 years 5 months ago #12188 by Moby
Replied by Moby on topic Re: Cartridge Overall Length differences.
Most definately. The weapon far exceeds my current ability.
I look forward to the learning curve and achieving my goal.

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