Reloading practices

[COLT45SA]

If I trim all my cartridges to precisely the same length and seat my bullets so that the carefully measured final OAL is the same, will that make a significant difference in how the loads group~??

 

[Bill Norris]

If I trim all my cartridges to precisely the same length and seat my bullets so that the carefully measured final OAL is the same, will that make a significant difference in how the loads group~??

Trimmed cases all to the same length is said to be helpful for tighter groups but seating carefully to the same OAL will not benefit at all. Cartridge base to ogive is the more precise measurement that yields consistent bullet entry into the lands. Over all length will not be consistent due to bullet length variation.

 

[Clancy]

Uniform case length and uniform CBTO.

Overall length means nothing.

You’re asking good questions though!

 

[Janeau]

OAL is important to consider for loading out of a magazine….CBTO is not telling you much for those more than a reference thereafter when seating bullet for those.

And depending of the type of guns..OAL mean everything for proper function.

 

[Clancy]

OAL is important to consider for loading out of a magazine….CBTO is not telling you much for those more than a reference thereafter when seating bullet for those.

And depending of the type of guns..OAL mean everything for proper function.

This isn’t that kind of forum though, is it?

If you’re feeding from a mag (like I am) then you should have planned ahead for that. I can run a bullet clean out the end of the case and still fit in the mags.

 

[Bill Norris]

If I trim all my cartridges to precisely the same length and seat my bullets so that the carefully measured final OAL is the same, will that make a significant difference in how the loads group~??

OAL is important to consider for loading out of a magazine….CBTO is not telling you much for those more than a reference thereafter when seating bullet for those.

And depending of the type of guns..OAL mean everything for proper function.

H was asking about tighter groups here. Hence my comment.

 

[COLT45SA]

Trimmed cases all to the same length is said to be helpful for tighter groups but seating carefully to the same OAL will not benefit at all. Cartridge base to ogive is the more precise measurement that yields consistent bullet entry into the lands. Over all length will not be consistent due to bullet length variation.

Well, sounds like I should measure length from cartridge base to ogive as OAL.

 

[Bill Norris]

Well, sounds like I should measure length from cartridge base to ogive as OAL.

Absolutely will be the most accurate measurement for group improvement.

 

[COLT45SA]

H was asking about tighter groups here. Hence my comment.

OAL is important to consider for loading out of a magazine….CBTO is not telling you much for those more than a reference thereafter when seating bullet for those.

And depending of the type of guns..OAL mean everything for proper function.

Rifle is single shot built on XP100 action

 

[COLT45SA]

Absolutely will be the most accurate measurement for group improvement.

Thank you. I should have thought of thst~!

 

[Bill Norris]

Thank you. I should have thought of thst~!

Very welcome Sir.

 

[ArtinNC]

Trimmed cases all to the same length is said to be helpful for tighter groups but seating carefully to the same OAL will not benefit at all. Cartridge base to ogive is the more precise measurement that yields consistent bullet entry into the lands. Over all length will not be consistent due to bullet length variation.

WOW new topic !!! I never though about that . Just checked 24 rounds that I have loaded and found 3 that were .011 different , so I marked them and will shoot them in the same group . I have a barrel stub gauge that I checked with in 6 BR . Why would some be different ??? The three that are different are once fired and the other seven are new brass .

 

[ArtinNC]

If I trim all my cartridges to precisely the same length and seat my bullets so that the carefully measured final OAL is the same, will that make a significant difference in how the loads group~??

What caliber is your XP100 ? I have two XP100 rifles .

 

[ArtinNC]

First picture is once fired and it shows .011 and the second picture unfired shows .003 , why would that be ? all loaded the same way nothing changed . With this gauge the bullet is touching the rifling and with the comparator set they measure the same OAL .

 

[Bill Norris]

WOW new topic !!! I never though about that . Just checked 24 rounds that I have loaded and found 3 that were .011 different , so I marked them and will shoot them in the same group . I have a barrel stud gauge that I checked with in 6 BR . Why would some be different ??? The three that are different are once fired and the other seven are new brass .

In this video Sam Milliard discusses the methods and differences between the two measurements. He also goes into the issue of length changes between measuring rounds loaded with fired brass and un-fired brass. The one fact that he drives home is the dangers of thinking one might be just touching in the lands BUT in reality jammed completely when flirting with "hot" loads.

 

[wkdickinson]

The problem with using a commercial (i.e., Hornady) "comparitor" to measure CBTO is that the diameter of the comparitor insert is very likely not the same as the diameter of your die's seating stem. Consequently, you will likely not get consistent CBTO measurements after seating. The reason is, in my testing I've found "ogive form" to be very inconsistent, even in what is considered high-quality commercial target bullets. So what I've done to remedy this is to make a comparator insert with a dia. as close as I can to the dia. of my seating stem (neither the original comparitor insert nor the one I made is even close to where the ogive actually meets the rifling). I then use a Sinclair "Seating Depth Gauge" to establish OAL to "touch" (what to "touch" is a different discussion), then using the same bullet, I seat it to the calculated OAL for "touch" and then measure the resulting CBTO, using the modified comparitor insert. That gives me a starting reference point, for seating depth, it also gives me very consistent CBTO measurements.

 

[ArtinNC]

Bill Norris . , I understand all that . When I'm saying OAL that is measured head to the Ogive , I'm not measuring to the tip of the bullet . When I measured with the barrel stub that was made with my reamer on a piece of 243 barrel so the bullets are touching the rifling . What I see is Loaded once fired round measured different than new brass loaded same set up .

 

[Bill Norris]

Bill Norris . , I understand all that . When I'm saying OAL that is measured head to the Ogive , I'm not measuring to the tip of the bullet . When I measured with the barrel stub that was made with my reamer on a piece of 243 barrel so the bullets are touching the rifling . What I see is Loaded once fired round measured different than new brass loaded same set up .

Yes Sir, Sam covers that in the video where he finds the same thing you are describing and he contributes that to the case growing from base to shoulder once it is fired.