hi-techammo 55gr FMJ-BT inconsistency

[bootcamp]

I recently bought some hi-techammo 55gr FMJ-BT. Excellent price at $65.00.

Just finished my last load of Montana Golds and opened up the H-TA stuff and weighed them at or close to 55gr. Ok, having used the montana gold stuff and never having to adjust the seater stem, I started seating the HTA stuff. Some would seat at the cannelure, some the cannelure would disappear into the case?

The MGs always measured long but safe at 2.250" consistently varying only .002 at most.

The HTA's seat at 2.210" - 2.250"

I'm doing this single stage but I really don't want to back out the seater stem for every round and start and build my way to the middle of each cannelure.

What are you guys doing for plinking ammo that is inconsistent like this?

Should I sort these projectiles with a "short" and "tall" group? I about drove myself crazy yesterday.

Thanks in advance.

 

[cheygriz]

Are all of your cases the same length??

 

[bootcamp]

1.750"

 

[243winxb]

What dies , press. Info from Lee> http://www.leeprecision.com/cgi/faq/index.cgi

Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

 

[bootcamp]

Guys, i'm sorry, I should have noted. I measured 25 bullets and although I don't have the measurements in front of me, they varied in length. Some cannelures were higher, some cannelures were lower. some projectiles were visibly taller some were visibly shorter. When I get home tonight I will post the variances in length.

Like I said, I didn't get this with montana golds. All my cases get trimmed down to 1.750" regardless, because I don't like measuring to trim, I just trim them all. They all get FL sized and trimmed. I don't like working with cases between 1.750" - 1.760". I like working with all uniform cases to 1.750". If the trimmer doesn't hit it, it's too short for me and I toss the case.

 

[ole farmerbuck]

Also, make sure the primers are seated below flush. Makes a difference when measuring.

 

[bootcamp]

Oh, i'm using a RCBS rock chucker with hornady new dimension dies. I am crimping at the cannelure when seating.

 

[bootcamp]

Also, make sure the primers are seated below flush. Makes a difference when measuring.

Yep I don't like high primers.

 

[243winxb]

Should I sort these projectiles with a "short" and "tall" group? I about drove myself crazy yesterday.

If you can't keep the variation .010" or smaller on a single stage press with dies set correctly, i would contact the seller and try to return the hi-techammo 55gr FMJ-BT

 

[243winxb]

hornady new dimension dies

Does this die have the sliding sleeve in the seating die? Could be your problem. Hornady>

The sliding sleeve vertically prealigns the bullet with the case-neck.

Projectiles with a difference of .040" is way to much. Send them back.

 

[Wildbillz]

Bootcamp
are they the USGI pull downs or the new mfg ones?

WB

 

[Walkalong]

The relationship between the ogive and the cannelure is what is important. I have the same problem with Winchester 55 Gr FMJ bullets. Sometimes the case mouth will be at the top of the cannelure, sometimes at the bottom, sometimes in the middle, and anywhere in between. I crimp them using a Reddding taper crimp die.

Evidently the MG bullets are just more consistent, as I would expect them to be. Most 55 Gr FMJ-BT bullets are cheap and intended for cheap plinking etc. They are not match quality and never will be.

If they are military pull downs, they were never intended for match accuracy either.

 

[ATCDoktor]

Most bulk rifle bullets I have bought have inconsistent cannelures.

Winchester, remington, IMI and PRVI (in my mind) are all just about the same quality when it comes to 55 grain FMJBT cannelure's.

Take 10 of any of those mentioned and line them up and look at them and the cannelures will be all over the place.

Most mfgrs bullets are consistent in length but their cannelures are not placed in the same place on every bullet.

If your montana golds are as consistent as you say I will be ordering from them asap.

 

[ole farmerbuck]

I bought 5 or 6 thousand Hornady 55gr sp w/cannelures and havent had any trouble........yet. Very consistant.

 

[Walkalong]

Winchester - Notice the inconsistency of the cannelure on a random 5 bullets I picked up.

 

[NCsmitty]

Years ago, I bought some bulk Winchester 55gr .224 FMJ, and I found the inconsistent cannelures and weight differences, like others posting. I shot a bunch but ended up selling the rest because they did not shoot well in anything.
Bullets like that are just good for random plinking.

Hornady FMJ's seem to be the exception, as ole farmerbuck mentioned. Their FMJ bullets seem much more consistent in measurement and performance.
They still do not usually shoot as well as a good HPBT.



NCsmitty

 

[Walkalong]

They still do not usually shoot as well as a good HPBT.

They have no chance. No matter how well made they are they still have the base of a FMJ, which is 90% of why they don't shoot particularly well compared to any decent SP or HP with a well formed square base.