SmallCaliberCentral

or just load to maximum COAL? I'm mostly wondering about those of you with Comparators. I see mixed answers and some of them are old when I research this. Many have either given up trying or note that they can only get within 0.185" from the lands if they bother checking with their comparator. Others have reported getting much closer.

Would like to hear from as many as possible: what is your experience? If the excessive throat is more than the amount a bullet is seated, is it even possible to measure throat erosion over time? Bought a modified case and .20 cal comparator disk, but am wondering if I wasted my money.

My rifle is still at my gunsmiths; haven't been able to evaluate the throat (Remmington SPS Varmint 204).

Thanks everyone

2.334" for a Savage VLP (bolt) and I did mess around with seating but couldn't shrink groups w/ it. Not sure how I ended up @ 2.334??... but I had great groups. As I recall I couldn't reach the lands...

2.245" in a RRA AR-15, but that's where I just set my seating die 'cuz they fit the magazine that way.

I know mightier men than I finess the COAL, and have seen good results doing so...

i agree with bow shot in my rifle didnt notice any difference either so just load to fit the magazine and left it at that cheers bazz

I'm not sure I understand your question?

I use the Stoney Point (Hornady) tool to determine the COAL w/ each Bullet type I reload.
Each individual Rifle has a differnt reading, and each type of Bullet will differ.

The other day I shot and chronograghed a load which was seated @ MAX OAL and had an Average velocity of 3800fps.
Several days later I shot the same load BUT with the COAL .004 off the rifling and it registered 3700fps.

I think the Stoney/Hornady measuring device is a must have tool for reloading.

Good Luck!

The Hornady comparator tool is a valuable piece of equipment. You can indeed keep track of throat erosion and also know exactly how far you are from the lands. I use mine for over 30 rifles.

If your 204 Ruger has a factory barrel, with the obligatory SAAMI-cut chamber, it's doubtful you'll ever reach the lands without the bullet falling out of the case. This is the way the cartridge was designed....for blistering speed using the 32 grainers by taking advantage of the excessive freebore a la Weatherby design.

You basically have two choices: Load to fit the magazine using 'book OAL', or experiment and find out peak accuracy nodes using different bullet seating depths. If you plan to get as close to the lands as possible, you'll be shooting single shot, as no 204 round "loaded out" to reach the lands will ever fit a factory magazine.

As noted though, keep in mind that every manufacturers bullet will give different readings, as they all differ in the ogive....some are tangent, some are secant and the readings will differ when using the comparator tool.

For a better understanding of ogive, check this out:

http://site.cuttingedgebullets.com/page ... escription

HTH

Most of mine reach full length in the magazine before they ever reach the lands in the barrel.

Rick in Oregon wrote:The Hornady comparator tool is a valuable piece of equipment. You can indeed keep track of throat erosion and also know exactly how far you are from the lands. I use mine for over 30 rifles.

If your 204 Ruger has a factory barrel, with the obligatory SAAMI-cut chamber, it's doubtful you'll ever reach the lands without the bullet falling out of the case. This is the way the cartridge was designed....for blistering speed using the 32 grainers by taking advantage of the excessive freebore a la Weatherby design.

You basically have two choices: Load to fit the magazine using 'book OAL', or experiment and find out peak accuracy nodes using different bullet seating depths. If you plan to get as close to the lands as possible, you'll be shooting single shot, as no 204 round "loaded out" to reach the lands will ever fit a factory magazine.

As noted though, keep in mind that every manufacturers bullet will give different readings, as they all differ in the ogive....some are tangent, some are secant and the readings will differ when using the comparator tool.

For a better understanding of ogive, check this out:

http://site.cuttingedgebullets.com/page ... escription

HTH

Thank you Rick for chiming in; I have read most of your posts on this topic and was hoping you would chime in.

I fully understand how to use my comparator and I'm sorry my original post was cryptic. Like you said: many rifles have such long throats that to reach lands the bullets would fall out of the case, and my pointed question was in this situation how in the world do you measure throat erosion if you don't know where you are to start with (due to bullets falling out of neck of the case)?

My other question was to try to help me guess whether my particular rifle would be any more likely to lend itself to making loads that I could seat near the lands. TucoTom on this thread that doesn't seem to have any trouble seating where he wants..... is this a custom or factory chamber? I have some 40g Bergers I'm going to start out with my new rifle..... are there other bullets that have a longer base to ogive measurement which might reach the lands easier?

Then, let's say I CAN load bullets near the lands.............. would you suggest as a starting point I try a particular distance...... such as .020 off the lands, or if you could would you try closer?

Thanks everyone

mpstan: Even if the bullet is out of the modified case when using the tool, you'll still be able to push the bullet into contact with the lands using the spud, then measure to monitor throat erosion. I've been doing this with my custom M700 223AI for ten years, and by monitoring the erosion, I know that I've eroded .045" of the throat, but can still seat to the lands, as it was cut with a custom reamer to touch the lands with zero freebore when new. My custom M700 11-twist 204 was cut the same way, and I'm still able to kiss the lands with that rifle also after five years of intense field use. This is not possible with factory 204 barrels.

With your Remmy barrel it's doubtful you'll be able to kiss the lands, but not to worry as most 204's seem to not mind jumps to the lands in excess of a whopping .100" or even a bit more. I'd start out with factory spec OAL, then try seating out in .010" increments until you find a sweet spot. But first find a load that gives decent accuracy at factory OAL prior to tweaking or you'll be chasing your tail. You only want to change one thing at a time, and seating depth is usually the last thing to get tweaked.

Good luck with the new rig. Let us know how she shoots when she's back. JME HTH

All of my barrels have short throats just so I can jam into the lands at least .010.
Everything I shoot (except my gas guns) starts off with the bullets jammed into the lands. You can always go shorter. And I single feed so I don't have to think about mag length.

Nor Cal Mikie wrote:All of my barrels have short throats just so I can jam into the lands at least .010.
Everything I shoot (except my gas guns) starts off with the bullets jammed into the lands. You can always go shorter. And I single feed so I don't have to think about mag length.

Mike are any of your barrels factory derived? Any Remys in that group? Are you finding .010 is the most accurate seating for your pet loads?

I have the comparator, measured my rem700 .204 and had the bullet fall out of the mod. brass. I definetly gather that nearly all .204 factory rifles are deep throated. My opinion-unless you get a reamer built to your desired dimension just find your load and let it fly. heck, my rifle has significant jump to the lands but can outperform me nearly any day of the week.

If I can shoot a .132" group with factory .204, seated at 2.25 COAL, do I really think seating out longer is going to improve my group size? I seat longer in my Cooper because its practical but my factory .204 is fine with 2.26 max COAL.

I picked up the Hornady tool a few months ago, and seem to be pushing the bullet too hard as I have had several 17 caliber bullets stick in the lands, having to push them out with a rod inserted very slowly. Any tricks besides not pressing so hard to make sure the bullet contacts the rifling properly? I've thought about sacraficing some brass by splitting the necks on my 17's and going to the old stand-by of closing the action on a dummy round to possibly keep from sticking bullets.


Rick, after buying a borescope and inspecting some of my old guns, I am surprised you haven't had to set your AI barrell back to keep your standard of accuracy! Is the throat "alligator skinned? My old target weight barreled Ruger 77 25-06 is pretty rough throated and fouls fast, but I used it for offhand running deer targets and hunting deer, it has always been a 3/4" gun for me but I never adjusted seating depth.


Sometimes the bliss of not knowing better ( 30 years ago) wasn't so bad, but I never shot small groups back then either.


Allen

hemiallen wrote:Rick, after buying a borescope and inspecting some of my old guns, I am surprised you haven't had to set your AI barrell back to keep your standard of accuracy! Is the throat "alligator skinned?

Sometimes the bliss of not knowing better ( 30 years ago) wasn't so bad, but I never shot small groups back then either.

Allen: When I had my 223AI reamer ground, I had it ground with zero freebore. By doing so, it allows me to "chase the lands" very accurately by using the SP tool (mine is from Stoney Point). That particular rifle now has .045" of throat erosion, and 'yes' it appears like alligator skin under magnification. Once it gets to .060", I'll set the barrel back, but that will be in another few years, as my .20 cals get more use now than my 223's do.

I love bliss too, but even 30 years ago I was tying for dinky groups, it's just easier now with better rifles, barrels and bullets. Skippy flies just like he used to in 1982, but now he does it more often, and at longer distances.

Allen, what borescope did you purchase?

Thanks Rick

I found out quick seeing a rough bore isn't a reason for concern, my better shooting remington barrels, although with little erosion or alligator surfaces, shoot better than visually indicated ( a lot of torn lands, material missing).


I forgot you make your reamers with little or no freebore for several reasons, good to know .060" is your "set back" measurment. I suspect you will set the barrel back even if the gun shoots good groups?

Can't wait for a reason to put a new tube on one of my guns, but with still getting my current arsenal ready for April is consuming my "custom gun" monies. Have to do more trips to Rochester to fund my obsession.


Thanks Rick


Allen