Loading (rifle) for accuracy / oal ?

[JD 500]

Posted a question about caliber reccomendation for P dogs in the lounge, and got some great responses. Some of the responses touched on accuracy, and namely changing oal to find the sweet spot.

I've played with powder charges to find the sweet spot, but have never adjusted oal (intentionally). I just seem to stick with the listed oal in load data.

I've tried in the past to figure out what the length of some of my chambers are ( length to rifle lands ), but I don't think it's ever been successful.
(Tried in bolt gun - Tikka T3 .300wm, and my AR .223 rem)
Also, relating to Pdogs I'm loading for an autoloader ( .223 rem AR ) which I think creates an oal limit, based on ammo fitting into magazines.

I just ordered "Precision shooting: Reloading guide" edited by Dave Brennan and plan to read up.

Seems like my reloads can easily make 1 moa, maybe a little better, but certainly not as good as say the 1/2 moa suggested for p dogs.
I think the equiptment is there, and the handload is where I should be able to improve.

I'll detail the equipt. below, but do you have any suggestions on :

How to find oal of chamber (tried smoking / sooting a bullet and looking for marks, with no luck)

Reading suggestions

load suggestions

any other advice on getting to the next level
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Equipment

The rifle : AR , DPMS 24" Bull 1:8 twist barrel , chamber is .223 rem (not 5.56)
Do have Timney 3lb trigger group installed, and if it isn't 3.0 lb, it's got to be close.

Glass : Leupold 4x14x50

The load(s)

Brass : Win trimmed to 1.750"
Primer : Wsr


50 gr Barnes Varmint Grenade
25.0 gr Varget. Seated to 2.200" (Data based on conversation w/Ryan at Barnes)

60 gr Sierra Hp Varminteer
26.5 gr Varget. Seated to 2.250"

60 gr Hornady V-Max
26.5 gr Varget. Seated to 2.250"

Also loading 69gr SMK (not for Pdogs)
25.7 gr Varget. Seated to 2.250" - So far this is most accurate load/bullet.


Since these cartridges are made for autoloader, all get crimped fairly heavy with a Lee Factory crimp die. If they don't get crimped, they pull out upon chambering.

Press - Rockchucker single stage. Each powder charge is weighed. cases turned 1/2 way around during priming, bullet seating, and crimping


Thanks in advance for your thoughts !

 

[Ron H.]

Sir, if your bullets are pulling out when you remove a chambered round, they're seated too long. It's usually best to keep the bullet ogive at least 10 thousandths off the lands. To accurately find where the lands start in your barrel, you'll need an ogive comparator and something like the old Stoney Point tool. (I think someone else makes it now.) Both can be had from Sinclair International, www.sinclairintl.com.

A further note on crimping bullets: As a rule, crimping is not conducive to the kind of accuracy you're after. Nor is it needed in an AR, even when feeding from the magazine, unless something else is wrong with either the gun or the load. Don't crimp a rifle bullet that doesn't have a cannelure (such as the Sierra Match King)--accuracy can be expected to suffer from this bullet deformation.

Another problem you may be having with the light varmint bullets is your barrel's twist rate. The 1:8 is designed for long, heavy bullets--up to and including 80 grains in the .223. Varmint bullets usually are more accurate in slower twist barrels such as 1:12 or even 1:14 for the really light ones.

Hope this helps, and Semper Fi.

Ron H.

 

[JD 500]

Thanks for the reply Ron.
As far as the bullets, I'm only using varmint bullets that indicate they are for twist rates of 1:10 or less (faster).

The bullet pull is happening when the cartridge stops abruptly in chamber after being picked from magazine (When the bolt slams shut). Or at least that is my assumption.

Wonder if I need to remove material from the expander plug in my sizing die to increase neck tension ?

Or maybe I need to start with that oal gauge to rule out your thought that I'm seated to long ?

 

[fredj338]

I agree w/ Ron, if the bullet pulls out after chambering, you are already wedged into the lands. You can find out the contact point by using an empty, unsized case. Pinch the mouth of the unsized case enough to hold a bullet firmly. Just seat the bullet & then gently push it into the chamber till fully seated. This should push the bullet further into the case. Use a cleaning rod w/ flat jag installed & gently push it into the bore until it stops against the bullet. Mark it on the rod at the muzzle & then remove the round & close the bolt, push the rod in further until it hits the bolt face & mark that on the rod at the muzzle. Now measure the diff. between the marks, that is your max. OAL as long as it fits the magazine. You will want to be a min. of 0.01" off the lands to keep the bullet from jambing into & causing pressure problems as well as spilling powder in the action if you have to unload.

 

[H Richard]

If your loading for an auto-loader, you are limited by the OAL to fit your magazine, Unless you want to single load every shot. To measure the OAl, get a Stoney Point, (Now Hornady) OAL gauge, and the specific case modified for it that your loading. A dial caliper. Follow the instructions on the OAL gauge. It isn't difficult. Guns are individuals. A lot of them like the loads crammed into the rifling, a lot of them like .0015 to .0020 off the rifling. When working up loads, I load 5 rounds each of the same load with OAL at .005, .0010, .0015, .0020 and see which groups the best at 100 yds. You can find your most accurate load.

 

[Ron H.]

Thanks for the reply Ron.
As far as the bullets, I'm only using varmint bullets that indicate they are for twist rates of 1:10 or less (faster).

The bullet pull is happening when the cartridge stops abruptly in chamber after being picked from magazine (When the bolt slams shut). Or at least that is my assumption.

Wonder if I need to remove material from the expander plug in my sizing die to increase neck tension ?

Or maybe I need to start with that oal gauge to rule out your thought that I'm seated to long ?

Sir, let me make sure I understand correctly: The bullets aren't actually being mechanically pulled out by the rifling, but rather are being pulled forward a bit on chambering, as when breaking down a cartridge with a kinetic bullet puller?

If that's so, then yes, you need more neck tension. Trimming down the expander ball can help, as can leaving it off altogether. You can also get a sizing die that takes different size neck bushings to suit your particular chamber and most-used brass. One such is the "Type S" die from Redding, which I've used, but I'm sure other outfits make a similar thing. Call up Sinclair, and they can talk you through the measurements needed to get the correct size bushing.

Was it me, I'd try resizing a few cases without the expander ball and then see what happens. That's the cheapest and simplest option, so it makes sense to try that first. In conjunction with that, I'd also shoot a few rounds for group, one batch crimped as you've been doing against the another batch of same loads with no crimp so you have a direct comparison.

It might also pay to shoot the "kinetically lengthened" rounds for groups as well, just to see how much difference that makes. It might not matter.

And yes, do get the comparator and Stoney Point setup. Chamber throat lengths in .223 vary all over the map, and you need to know your specific barrel if you're going to get the kind of accuracy you want.

Where are you at in Colorado? If you're in or near Denver, I'd be happy to walk you through some of this stuff in person. I don't have any .223 loading gear any more, but I do still have the Stoney Point tool itself and comparator. Lemme know.

Hope this helps, and Semper Fi.

Ron H.

 

[zercool]

50 gr Barnes Varmint Grenade
25.0 gr Varget. Seated to 2.200" (Data based on conversation w/Ryan at Barnes)

60 gr Sierra Hp Varminteer
26.5 gr Varget. Seated to 2.250"

60 gr Hornady V-Max
26.5 gr Varget. Seated to 2.250"

Also loading 69gr SMK (not for Pdogs)
25.7 gr Varget. Seated to 2.250" - So far this is most accurate load/bullet.

I've got a DPMS with a 20" 1/8 barrel that has done acceptably well with 55gr FMJ. I wouldn't go any lighter than 55gr with that twist rate, and generally speaking would expect better accuracy from the 62gr and up weight range.

If the 69gr matchkings are your most accurate thus far, I'd be looking for less expensive bullets in that weight class - 62, 65, 70gr, etc. I just picked up a box of 70gr Barnes TripleShock that I'll be testing for deer nuisance permits this summer.

The other thing you may consider doing is starting to tweak by tenths of grains of powder, if you haven't done so already.

Looking forward to hearing results!

 

[JD 500]

I agree w/ Ron, if the bullet pulls out after chambering, you are already wedged into the lands. You can find out the contact point by using an empty, unsized case. Pinch the mouth of the unsized case enough to hold a bullet firmly. Just seat the bullet & then gently push it into the chamber till fully seated. This should push the bullet further into the case. Use a cleaning rod w/ flat jag installed & gently push it into the bore until it stops against the bullet. Mark it on the rod at the muzzle & then remove the round & close the bolt, push the rod in further until it hits the bolt face & mark that on the rod at the muzzle. Now measure the diff. between the marks, that is your max. OAL as long as it fits the magazine. You will want to be a min. of 0.01" off the lands to keep the bullet from jambing into & causing pressure problems as well as spilling powder in the action if you have to unload.

This method would give a measurement of bolt face to bullet tip right ? (OAL)
And I would need to make this measurement for each different bullet I load, based on different placements of the ogive on each different (shaped) bullet (ie vmax vs varmint grenade, etc...).

Does the stoney point/Hornady oal gauge measure bolt face to start of rifling ? So I can use that measurement in conjunction with the comparator on my calipers on any bullet ?


H Richard - Will magazine length always be shorter than oal of chamber ?
and when you test seating depths, do you see what powder charge groups well first, and then test seating depths second ?

Ron H - Yes, I assumed it was kinetic energy pulling the bullet, not rifling hanging on to it while ejecting. I really can't say for certain. If I took two prepped cases with a bullet seated as I've been doing (without crimp), loaded one from mag, and hand placed the other carefully closing bolt with foward assist if needed, then measured the two, would that indicate which issue I have ? ( longer oal in from mag sample, but not gentle handplaced sample = kinetic, Longer oal in both samples = wedged in rifling )

 

[Ron H.]

This method would give a measurement of bolt face to bullet tip right ? (OAL)
And I would need to make this measurement for each different bullet I load, based on different placements of the ogive on each different (shaped) bullet (ie vmax vs varmint grenade, etc...).

Does the stoney point/Hornady oal gauge measure bolt face to start of rifling ? So I can use that measurement in conjunction with the comparator on my calipers on any bullet ?


H Richard - Will magazine length always be shorter than oal of chamber ?
and when you test seating depths, do you see what powder charge groups well first, and then test seating depths second ?

Ron H - Yes, I assumed it was kinetic energy pulling the bullet, not rifling hanging on to it while ejecting. I really can't say for certain. If I took two prepped cases with a bullet seated as I've been doing (without crimp), loaded one from mag, and hand placed the other carefully closing bolt with foward assist if needed, then measured the two, would that indicate which issue I have ? ( longer oal in from mag sample, but not gentle handplaced sample = kinetic, Longer oal in both samples = wedged in rifling )

Sir, the cleaning rod method will give you a coarse measurement to the bullet tip and thus is bullet-specific because bullet tips and ogives differ. You'd have a different measurement for every bullet. Bullet tips can vary considerably, even within the same box from the same manufacturer. This is particularly true of hollowpoints such as the Sierra Match King. You want to measure from where the ogive touches the rifling, not from the tip.

The Stoney Point tool measures from where the bullet's ogive touches the rifling, so is also bullet-specific, but is more precise than the cleaning rod method. You can measure it with your dial calipers. A comparator also measures based on each bullet's ogive, which is what you want, but it still isn't a "one size fits all" proposition.

Sinclair sells a tool that measures from the bullet's base, but even that depends on exactly where each different bullet's ogive hits the rifling. This is a long way of saying that you'll need to take measurements for each different bullet you use.

Magazine length *should* be shorter than the chamber throat. If it isn't, whoever chambered your barrel screwed up. This can certainly happen, but I personally have never seen it.

Yes, chambering one round from the mag by letting the bolt fly and another with only hand pressure should tell you whether you have kinetic bullet pull going on. Measure each round before and after with a comparator. If you're getting significant pull, look for rifling marks on the "pulled" bullets. I doubt you'll find any, but if you do, your chamber throat's cut too shallow and the gun needs the attention of a good 'smith. More likely, though, there won't be any rifling marks on the bullet. That would suggest insufficient neck tension, most likely meaning something's wrong with either your brass or your size die.

Hope this helps, and Semper Fi.

Ron H.

 

[JD 500]

Thanks Ron !!

And sorry, didn't mean to skip over it, Yes I am in the Denver area. ( SE - between denver and aurora.) And I may just take you up on your generous offer. Where do you shoot ?

I am going to pick up the oal guage, as I'm loading for about 4 rifles with different bullets for each. Seems like a no brainer to know the dimensions of each chamber.

 

[Ron H.]

Thanks Ron !!

And sorry, didn't mean to skip over it, Yes I am in the Denver area. ( SE - between denver and aurora.) And I may just take you up on your generous offer. Where do you shoot ?

I am going to pick up the oal guage, as I'm loading for about 4 rifles with different bullets for each. Seems like a no brainer to know the dimensions of each chamber.

Sir, for rifles, I normally shoot at the Colorado Rifle Club (www.crci.org) outside of Byers. I'm a member there. We're holding a Garand match on Saturday that I'm planning to attend, so we could meet up there if you wish. Details about the shoot should be on the CRC Web site.

For pistol shooting, I normally go to The Shootist off Dartmouth and Galapago.

Hope this helps, and Semper Fi.

Ron H.

 

[JD 500]

Ron - Thanks for the offer - wish I could make it but I'm booked for this weekend. Good luck in the match, sounds like fun, big time.

I just went and did a little testing, and also had a conversation with RCBS.

Seated a 69gr smk into prepped case col = 2.252".
Loaded into chamber by hand, closed bolt.
Opened bolt, cart. ejected. measured col = 2.252".

Loaded same cart into mag, and chambered from mag. Opened bolt, ejected, and measured col = 2.255" , pulled .003 out.

Called RCBS and explained. Rep is sending 2 expander plugs to me.
another .223 rem which she will confirm measures .223", AND, an expander plug for .22 jet which she said will measure .222".

Otherwise, she indicated I should really be using bullets with cannelures.

Will a bullet with a cannelure, crimped w/ Lee fcd, be as accurate as a non cannelured bullet w/ no crimp ?

Thanks much,

 

[Ron H.]

Ron - Thanks for the offer - wish I could make it but I'm booked for this weekend. Good luck in the match, sounds like fun, big time.

I just went and did a little testing, and also had a conversation with RCBS.

Seated a 69gr smk into prepped case col = 2.252".
Loaded into chamber by hand, closed bolt.
Opened bolt, cart. ejected. measured col = 2.252".

Loaded same cart into mag, and chambered from mag. Opened bolt, ejected, and measured col = 2.255" , pulled .003 out.

Called RCBS and explained. Rep is sending 2 expander plugs to me.
another .223 rem which she will confirm measures .223", AND, an expander plug for .22 jet which she said will measure .222".

Otherwise, she indicated I should really be using bullets with cannelures.

Will a bullet with a cannelure, crimped w/ Lee fcd, be as accurate as a non cannelured bullet w/ no crimp ?

Thanks much,

Sir, all my AR loading was with SMKs (no cannelure), so I can't answer that question. I imagine it would depend on the particular gun and load. FWIW, though, I don't know any serious high power guys who use cannelured bullets for matches.

Hope this helps, and Semper Fi.

Ron H.

 

[JD 500]

Sir, all my AR loading was with SMKs (no cannelure), so I can't answer that question. I imagine it would depend on the particular gun and load. FWIW, though, I don't know any serious high power guys who use cannelured bullets for matches.

Hope this helps, and Semper Fi.

Ron H.

Hi Ron,

Do you by chance have any of your old measurements (OAL of your AR chamber) with 69gr smk's ?

Just received my Stoney point / Hornady OAL tool and measured my chamber.
Measured 3 times, same result each time = 2.412"
Hodgdon has listed 2.235" in thier data, and I know that oal is designed to work in all chambers, but at 2.412" Is that .177" difference realistic, or does that show throat erosion ? Rifle has seen rounds, but probably no more than 400-500.

My mags will definitely be shorter than that.

 

[Ron H.]

Hi Ron,

Do you by chance have any of your old measurements (OAL of your AR chamber) with 69gr smk's ?

Just received my Stoney point / Hornady OAL tool and measured my chamber.
Measured 3 times, same result each time = 2.412"
Hodgdon has listed 2.235" in thier data, and I know that oal is designed to work in all chambers, but at 2.412" Is that .177" difference realistic, or does that show throat erosion ? Rifle has seen rounds, but probably no more than 400-500.

My mags will definitely be shorter than that.

Sir, I only loaded 77s and 80s, no 69s, so have no data for those. I loaded the 77s to magazine length (a shade less than 2.250" nominal) since they had to feed from the mag for rapid fire. I loaded the 80s long since I was single-loading them at 600 yards. They were 2.870" OAL as measured with my comparator.

(The comparator adds length to the measurement--the actual overall length was less than 2.870", but because SMK tips vary in length, I never bothered to measure this. Where the ogive hits the lands was more important to me. Also, each comparator is different. It doesn't give you absolute data, but so long as you use the same comparator and the same bullet, you get good comparative data, hence the name.)

My match rifle had a Wylde chamber, which is different from a standard .223 chamber in that the throat's a little longer (deeper). Measured with an SMK 80 and my comparator, my chamber measured 2.880" from the bolt face to where the bullet's ogive touched the lands.

Hodgdon's 2.235" number is based on magazine length, not chamber throat length. Your 2.412" number is telling you where the lands start in your specific barrel with the specific bullet you used in the measurements. The difference is not unusual even in brand-new barrels.

If you want to load so that your bullets are 10 or 20 thousandths off the lands, you'll need to load them longer than magazine length. This can help accuracy (though it doesn't always), but you'll have to single-load. Which is the better option is something only you can decide.

Hope this helps, and Semper Fi.

Ron H.

 

[WR Moore]

A couple of suggestions here. First, a light taper crimp (0.001" or so) on a SMK will not noticably degrade accuracy. The stresses the bullet undergoes passing down the bore will iron out any minor discrepancies.

Secondly, I notice you're using Varget. Nothing against Varget, but it might not be the best powder selection for the weight of bullet involved. I use 748 under 69 gr SMKs, RE15 under 75 gr Hornaday HPBTs and IMR4198 for 60 gr and under. These various powders produce better groups in my rifle than other selections, well under 1 MOA.

 

[JD 500]

Thank you gentlemen !!!

Sounds like mag length will be the limiting factor.

RCBS is sending me new expander buttons/plugs to try and increase neck tension as to avoid heavy crimping.

Thanks very much for your thoughts and replies !!


P.S. Ron - How was last weekends match ?

 

[Ron H.]

P.S. Ron - How was last weekends match ?

Sir, the match went well--good turnout and some very good scores. The wind came up just in time for the offhand stage on the second relay, but that's the natural order of things out there. The match winner shot a 280-something with an '03 Springfield. I personally didn't shoot worth a darn. Started off well with a 97-3x in slow prone, but my prone rapid and offhand were both lousy. That's what happens when you don't practice. :-/

Hope this helps, and Semper Fi.

Ron H.

 

[JD 500]

Sir, the match went well--good turnout and some very good scores. The wind came up just in time for the offhand stage on the second relay, but that's the natural order of things out there. The match winner shot a 280-something with an '03 Springfield. I personally didn't shoot worth a darn. Started off well with a 97-3x in slow prone, but my prone rapid and offhand were both lousy. That's what happens when you don't practice. :-/

Hope this helps, and Semper Fi.

Ron H.

It is a perishable skill, I've noticed with my own shooting.
Thanks again for your help (Everybody) !