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Old October 26, 2012, 07:57 PM   #1
Jimro
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Possum Hollow Trimmer

So today I was reloading some 5.56 brass and was thinking about the recent thread where the OP was disappointed in the WFT power trimmer. I thought I might check out how the Possum Hollow trimmer I was using fared in the precision department.

Full length resize, remove crimp, trim with possum hollow trimmer, deburr with a hand tool.

After I was complete I randomly pulled 30 cases from the top of the coffee can and measured using a made in china dial caliper.

1.755
1.760
1.752
1.757
1.749
1.756
1.753
1.752
1.751
1.755
1.754
1.749
1.750
1.753
1.755
1.750
1.750
1.755
1.752
1.749
1.751
1.757
1.750
1.754
1.756
1.755
1.751
1.760
1.754
1.751

0.0025612366 Average Deviation
1.7532758621 Average
0.0030670664 Standard Deviation

I thought I had a lot of nothing but LC07, but when I hit the first 1.760 I turned it over and saw the WCC and NATO cross on the bottom, so this was a mixed lot between Lake City and Winchester which probably skewed the numbers a bit as the Winchesters measured long.

The specs for the 223 Rem show a Neck length of 0.202765 inches in length. So a standard deviation of .0031 inches puts the low end at 0.19998 and a high at 0.20586, which is a 3% variance range in neck length (1.5% up and down).

My last trip to the range with the match load I use this brass for had an extreme spread for the 10 shot group was 2.375 inches. Subtract the furthest flyer and the ES dropped to 1.5 inches, and if you drop the furthest out then the 8 shot group went to 1.25 inches. So whether the wind was working against me by knocking the target around or whether I'm not that great from an unrested (from the bench, but no bags or bipod) rifle using iron sights at 100 yards is also a factor to consider.

I may start segregating my brass more for the 600 yard line from here on out, although my 600 yard line load uses an 80 gr Amax which shoots tighter than the 75gr PRVI HPBT I was using.

Jimro
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Old October 26, 2012, 08:50 PM   #2
greentick
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Thanks for the info, I also have a possum hollow trimmer for 556/223.
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Old October 27, 2012, 07:17 AM   #3
rebs
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So the bottom line is, is the possum hollow trimmer a good tool or not ?
I use the Lee case trimmer and my cases come out right on the money, but its a pain in the fingers to lock each case in the shell holder when doing large amounts of brass.
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Old October 27, 2012, 01:50 PM   #4
Jimro
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Rebs,

For feeding an AR-15 it is a great tool. I'm going to keep using it.

I've been thinking about my earlier assumption in that the variation in length of the cartridge is in the neck. I don't have any proof that the variation is in the neck, it is just a guess on my part.

If you are looking for consistent neck tension, it is probably better to use the Possum Hollow tool, since it measures from the shoulder datum instead of the case head. I'm thinking I should go back and actually measure more of the cartridge if I can get precise measurements to figure out if the length variation is in the body.

If the variation is in the body (as I suspect) then the neck lengths will be extremely uniform. With the Lee trimmer the overall length will be very uniform, but if there is variation in the body length the necks will be less uniform.

Jimro
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Old October 27, 2012, 03:17 PM   #5
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Jimro
Thanks for the information, I think I am going to order the possum hollow trimmer
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Old October 28, 2012, 09:47 AM   #6
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Ive been thinking about picking up one of these. Also interested in the WFT trimmer.
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Old October 28, 2012, 07:52 PM   #7
greentick
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I will keep using mine for AR feeding.
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Old October 30, 2012, 08:32 AM   #8
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Quote:
If the variation is in the body (as I suspect) then the neck lengths will be extremely uniform. With the Lee trimmer the overall length will be very uniform, but if there is variation in the body length the necks will be less uniform.
I think that is the real difference in how the two trimmers work.

However the use of a case gauge, like the JP Rifles model, does really help with monitoring the case body length/headspace as well as integrity at the base.

If using a case gauge then really either trimmer should do an equally good job, except that the PH can be customized to whatever length you want, while the Lee cannot.
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Old October 30, 2012, 09:03 AM   #9
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I love mine. It gets better as you develop a "feel" for when it bottoms out. It also helps to use a drill with a good bit of torque and speed. When I first got mine I used an old rechargeable with a tired battery. I struggled. Then got a new corded model. Voila!

Jimro, that bit of shooting with iron sights is, as you know, excellent.
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Old October 30, 2012, 09:09 AM   #10
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I would think from these posts that the Possum Hollow trimmer works the same as and just just as well as the WFT, am I right ?
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Old October 30, 2012, 10:05 AM   #11
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Anything that indexes off the shoulder/datum will work exactly the same (WFT, PH, Giraud, Gracey). But they all also assume that the base to shoulder/datum sizing is correct, which is why the case gauge really helps.
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Old October 30, 2012, 10:07 AM   #12
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Rebs,

They do work the same, but I haven't used the WFT to compare the two. The WFT might use different materials that may cause it to have a different useable life as a tool, which might justify the higher price. Can't say for sure.

But in terms of variation that I'm getting verses what others have reported from the WFT, I'm not going to bother buying a WFT to find out. In fact I'll probably buy a Possum Hollow trimmer for my next big batch of 7.62 M80 brass.

Moxie,

Unfortunately it isn't "excellent" with the crowd I've been shooting with. An old gentleman I've shot with, High Master rated, is able to hold around .75 of an inch for a 10 shot group at that range, from the standing position (I watched him do it on a reduced course High Power match). Of course he has decades of experience in High Power and I keep getting interupted by the Army to go to Iraq/Afghanistan/NTC/JRTC or School (I lost my entire summer to Fort Sill this year, totally blew my High Power season to bits).

I didn't start competing until about 2 years ago, but it is an addicting hobby.

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Old October 31, 2012, 04:38 AM   #13
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Are you serious? Those numbers are acceptable to you? Just glancing at those readings, I see a max of .010 from long to short.

I MIGHT accept a max variation of.001 to .003, but no more. I trust my lee system to be that close, usually it does better than that being dead nuts on each time.

I'll bet that the reason you're seeing that much variation is because it's not cutting square with the mouth of the neck. I have no idea how they work, and I'm not going to buy one to find out. All I know is people like them for the speed, but this is the first time I heard they don't hold better tolerances.

BTW, thank you for your service!
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Old October 31, 2012, 07:29 AM   #14
Jimro
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Snuffy,

I'll look at doing a batch of just one headstamp and see how that works out. Also I'll order an LE Wilson case gauge to see if the variation is in the neck or the body. If it is in the body I really don't care, as neck tension seems to matter more for accuracy (.010 variation in the body is a MUCH smaller variation by percentage).

Personally as long as the ammo can shoot tighter than I do I'm happy with it.

And you are welcome, thank you for a paycheck.

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Old October 31, 2012, 08:42 AM   #15
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Jimro,

There's always old Hawkeye to keep the rest of us humble. BTW, still getting half my pay.
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Old November 1, 2012, 11:09 AM   #16
Jimro
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20 rounds of twice fired LC07, full length sized in a Lee die, inner burr removed by hand, second trim after my first reload (all cartridge brass had material removed so my assumption is that it is a valid measurement of the trimmer's consistency). I left the outside burr on just in case I might have removed too much material and screwed up my measurement before.

1.752
1.755
1.752
1.753
1.751
1.752
1.752
1.752
1.752
1.753
1.755
1.752
1.754
1.752
1.752
1.754
1.755
1.752
1.753
1.752
0.001 Average Deviation
0.0012085224 Standard Deviation
1.75275 Average
0.004 Extreme Spread

Still don't have a Wilson gauge (yet) to see if the variation is in the body or the neck, but this level of variation is completely acceptable for me for feeding a semi auto AR-15.

Jimro
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Old November 1, 2012, 02:05 PM   #17
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Jimro, that's better but if you were to be crimping into a cannelure, you'd be all over the place, top to bottom of the groove. No, I don't crimp any .223's. As for bullet/neck tension, there would still be some variation.

I just got some LC once fired .223 brass from here;

http://www.mredepot.com/servlet/StoreFront

MRE brass was shipped in a re-painted green ammo can, the total for 500 pcs was 50.09 including shipping. They had been tumbled before shipping.

I just finished FL sizing and removing the primer crimp,(Hornady cutter). So the next step is to trim. I just did 15 with the lee set-up. Measured every one of them, ALL were at 1.751! No variation. Some were very long, as much as 1.768, others only barely cleaned up the mouth.

Your point as to is the length variation being caused by differences in the neck length is only a concern if you're aiming to get the same neck length to control neck tension. I'd think that it's more of a concern with the lee system, than with a trimmer like the possum hollow, gracey, or the WFT. Since they control length by gauging off the shoulder.

I control the shoulder position by use of a RCBS precision mic, Reading factory shells fired in my AR. Then sizing to .003 less than that reading. One way to find out if the necks are different lengths would be to see if all the shells positioned the shoulders to the same readings on the prec. mic.

Since the lee trimmer reads off the bottom of the case head, it could have variations in the neck length.
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Old November 1, 2012, 05:41 PM   #18
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Well, I just received my WFT today. I was going to order a PH trimmer but they seemed to be out of stock at all my usuall vendors. Ill post after I fire it up tonight.
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Old November 1, 2012, 06:30 PM   #19
Jimro
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Snuffy, you wrote:
Quote:
that's better but if you were to be crimping into a cannelure, you'd be all over the place, top to bottom of the groove.
The width a human hair is about .004 inches, which is the extreme spread. A cannelure is around .050 inches, so the extreme spread is less than 10% of the width, so I think that you might be a tad off the mark by "all over the place."

And if I were crimping into a bullet, it would be a 77gr bullet for a Mk262 clone and I'd be less concerned about neck tension.

I also have the Lee trim equipment, and it does give the exact same measurement each time, but until I get an LE Wilson guage to find out where the variation is (in the neck or the body) it is just opinion as to which is more accurate.

Jimro
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Old November 1, 2012, 06:59 PM   #20
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I love my WFT. I havent had any issues with it yet. Its fast and trims all my cases exactly the same everytime. Its not hard to set. Probably the fastest and most accurate trimmer Ive ever used.
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Old November 1, 2012, 07:22 PM   #21
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Jimro, there's been past discussions regarding the Wilson gauge's use and "shortcomings". It will absolutely do what you're thinking in that it will measure the base to shoulder. However it is cut to a wider diameter than an actual .223 spec so it does not function as a "case gauge".

I'm a big fan of the JP Rifles case gauge, which does exactly the same things as the Wilson gauge, but is cut to .223 Wylde spec so it can function as a case gauge - as long as .223 Wylde is acceptable to you.

I have one upper that is tight, rounds that pass the Wilson gauge sometimes will not chamber or extract from that upper. On the other hand, any case that passes the JP gauge will chamber and extract (at least so far).

Sometimes brass just wins the battle over the sizing die. The JP gauge will catch those rogue brass, the Wilson doesn't always catch them.
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Old November 2, 2012, 06:29 AM   #22
rebs
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When brass stretches, does it stretch in the neck area or the body of the case ?
Wouldn't a properly adjusted fl die put the shoulder right where it should be and leave any inconsistency in length in the neck area where the possum hollow and the WFT consistently trimming the neck to the right length for consistent neck tension ?

BTW I called Possum Hollow and he will have the trimmers back in stock late next week if anyone wants to order one directly from him. He also told me that they have carbide trimmer blades.

Last edited by rebs; November 2, 2012 at 06:35 AM.
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Old November 2, 2012, 06:55 AM   #23
Jimro
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Rebs,

Brass stretches in the body body due to gas pressure, and the neck gets longer due to brass flow from that pressure.

A full length resize is meant to squish the shoulder back down into the body, but what it often really does is just squeeze the neck further back down, lengthening the neck and giving the appearance of pushing the shoulder back. This is why your OAL on the brass can actually grow during the resizing process (not always, but it can because you are squeezing shoulder into neck and body into shoulder). This is why we trim brass in the first place.

As far as whether using a Possum Hollow or Lee trimming stud is going to produce more accurate ammo, the answer is a decided, "maybe" on both accounts. The most meticulous handloader I know swears by the Lee trimmers for his 308 accuracy loads, and they are what I generally use. I bought a few thousand once fired Lake City brass earlier this year, and using the Lee trimmer on them was way too time consuming, hence the Possum Hollow trimmer.

If I were a benchrester I would be paying a lot more attention to my brass prep than simply sizing, trimming, and loading. But auto loader brass is only expected to be viable for about 4 reloads anyways, so as long as my match loads are good for High Power, then that is good enough for me (for now).

Jimro
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Old November 2, 2012, 07:07 AM   #24
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Wow these case shoulder/drill type trimmers are great. Did around 300 223 last night with my WFT. Was going around 3-4 seconds a round. The WFT trimmer to .001 as advertised. I love it. After I got the trimmer dialed in I waited til I would measure about every 30 rounds. Then after I was done I randomly measure about 50 rounds. Everything was 1.750-1.749 with only 2-3 flyers. Im totally impressed. My hand was a little sore after 300 and the trimmer threw shavings EVERYWHERE! Oh well. 20 seconds with the shop vac cleaned it up. I recommend everyone pick up a trimmer of this style for high volume trimming. the PS, WFT or the CTS trimmer all function the same way and all appear to be well built.
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Old November 2, 2012, 09:15 AM   #25
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Quote:
Are you serious? Those numbers are acceptable to you? Just glancing at those readings, I see a max of .010 from long to short.
i have had my WFT for about three months and trimmed over 1,500 LC-00 to LC-10, after set up i measured the first 20 cases and believe it or not, all 20 cases measured exactly the same 1.750", i crimp 55 gr. and 62 Gr. FMJBT's in the cannelure with a Lee factory crimp die, the finished ammo is then put in my Dillon polisher for about an hour to remove sizing lube, "dirt", etc., they look like "factory new" ammo. i absolutely insist on clean ammo, it helps reduce fouling in the chamber and cleaning made much easier.

BTW, my Lee factory crimp die seems to stick, so i made some alterations.., which needs a post of it's own to explain.
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