OAL and feeding issues

[Paul-the new guy]

I am trying to get a 100% reliable load for my new limited gun. It is a .40 with a 5" Barsto barrel and it is new and tight. I have about 300 rounds through it now and am working on my major load. I had some rounds loaded 1.185 using 4.7grns of N-320 they missed major by just a tad coming in at 161pf. Durning testing I had a couple that nosedived and one of the GM's at the range said it was because they were too short. So I came home and loaded 5.0grns with an OAL of 1.200. This load made major but only 169pf and I had several rounds that got hung up on the feed ramp. They fit the chamber fine and they fit in the magazine fine but they don't like to feed. I shortened them up 1.190 and still had a couple of rounds that didn't want to feed but while testing I noticed this same load that made 169pf at 1.200 when shortened by .010 now was at 174pf on the chronograph. Still not happy with the feeding I shortened them back up to 1.185 and the pf jumped to 175 no nose dives, yet and I think they fed 100% I may try some 1.180's and see if they nose dive, maybe I was going the wrong way?

question 1: Does a round nose diving indicate an OAL that is too short?

question 2: Does it sound right that a .010 reduction in OAL increased the power factor by 5 from 169 to 174?

question 3: Is N-320 temperature sensitive? It was Africa hot here today and my ammo was laying in the sun...

[fastarget]

What type of bullet, and more importantly have the magazines been tuned?

[bbbean]

Step one: Find the OAL that will feed reliably in your gun. Pay no attention to PF during this phase.

Step two: Once you know what OAL your gun likes, THEN adjust the powder to get the PF and accuracy you need.

FWIW, I've found that the longer I load the more reliable my load gets. I've run as long as 1.26, but typically run between 1.20 and 1.22. Below 1.2 and I start to get misfeeds if ANYTHING else is out of whack (i.e. gunked up extractor,dirty feedramp, etc). Past 1.2, and my lim guns run even when they need cleaning.

Edited September 12, 2011 by bbbean

[Paul-the new guy]

The magazines are Brazos tuned magazines, bullets are Montana Gold 180JHP. The problem seemed to get worse as I went longer, the 1.20 rounds got jammed on the feed ramp, did I not go long enough? What would cause the rounds to nose dive? The gun is clean, the extractor and breach face are both clean. It is tough to diagnose this because nothing wants to feed when I go slow enough to see whats happening

Edited September 11, 2011 by Paul-the new guy

[Ofishl1]

The magazines are Brazos tuned magazines, bullets are Montana Gold 180JHP. The problem seemed to get worse as I went longer, the 1.20 rounds got jammed on the feed ramp, did I not go long enough? What would cause the rounds to nose dive? The gun is clean, the extractor and breach face are both clean. It is tough to diagnose this because nothing wants to feed when I go slow enough to see whats happening

I was loading some 155g Berrys for a new Edge I got a couple of weeks ago, I loaded to 1.130 just following the manuals, they all ran good, but 2 misfed out of 200, maybe a fluke...prob not

However, after I talked to some comp loaders I shoot with, they said absolutely go up to 1.180 and get the nose closer to the feed ramp, so I have run both and they seem to run the best at the longer OAL, I just loaded 200 185g eta 180g Berrys RSFP at 4.7 BE, they were all at 1.170 and not one hiccup, so maybe the best thing is to load shorter (watch pressure) and move out until you find the sweet spot, from my tests I believe I can expect consistent feeding from 1.150 out to 1.190

Edited September 11, 2011 by Ofishl1

[fastarget]

Each gun is different with different bullets, some eat anything, some are finicky, sounds will need to experiment a bit to see what your gun will like, my initial thought is that your gun likes the 1.18-1.185........shorter aol may also be wise to drop a tenth of a grain or two since the pressures are going up as you insert the bullet further.

Edited September 12, 2011 by fastarget

[noylj]

My .40s (2 Paras and an EAA Witness) like 1.200-1.220" COL.

If the magazines are tuned, what were they tuned to?

You can slow cycle by hand and see where the magazine is releasing the round and if the round will go up or plow into the feed ramp. I can't use slow hand cycling to verify the rounds will feed reliably, but it does show me where problems could be.

Have you simply dropped a bullet into the chamber and determined what your barrel's max COL with that bullet? I find that my best COL is often about 0.01" less than the barrel's Max COL for a specific bullet.

The only thing to watch out for is if the longer rounds flatten out as they go down the magazine and cause a jam. Be sure to load at least one magazine full and verify that the length works in your magazine before you load several hundred.

[CocoBolo]

Funny my load is 1.185 works like a champ. So if it isn't broke don't fix it. I run mine at about 172 pf, aka 5.0gr of N320 w 180gr Jacketed or 4.5gr with 185gr Precision same length. In 40 I prefer Dawson followers, they have proven to be most reliable but you lose a round of capacity just get 20 in the mag w/ an SNL. I have not seen any wide swings in velocity between 110 and 40 or from lot to lot.

Edited September 13, 2011 by CocoBolo

[Paul-the new guy]

My .40s (2 Paras and an EAA Witness) like 1.200-1.220" COL.

If the magazines are tuned, what were they tuned to?

You can slow cycle by hand and see where the magazine is releasing the round and if the round will go up or plow into the feed ramp. I can't use slow hand cycling to verify the rounds will feed reliably, but it does show me where problems could be.

Have you simply dropped a bullet into the chamber and determined what your barrel's max COL with that bullet? I find that my best COL is often about 0.01" less than the barrel's Max COL for a specific bullet.

The only thing to watch out for is if the longer rounds flatten out as they go down the magazine and cause a jam. Be sure to load at least one magazine full and verify that the length works in your magazine before you load several hundred.

When I ordered the magazines from Brazos, they did not give me an option of what length to tune them to. I have not attempted to see what the max OAL for the chamber would be but I can tell you it is greater than 1.200 The rounds I loaded to 1.200 went in with no problems and I could easily spin them, they were not contacting the rifling. I ran inot just what you are saying with some longer rounds I had loaded for my Glock so I would do that for sure.

Funny my load is 1.185 works like a champ. So if it isn't broke don't fix it. I run mine at about 172 pf, aka 5.0gr of N320 w 180gr Jacketed or 4.5gr with 185gr Precision same length. In 40 I prefer Dawson followers, they have proven to be most reliable but you lose a round of capacity just get 20 in the mag w/ an SNL. I have not seen any wide swings in velocity between 110 and 40 or from lot to lot.

Maybe the nose diving issue was because the mags and gun are brand new. I am going to load another 50 or so at that OAL and give them a shot. The magazines I have from Brazos have Grams followes and S.N.L. Dawson base pads. If you like the precision bullets, you would love Bayou bullets... The consistent velocity you are getting with the wide range in temperature leads me to assume that the increase in velocity I saw was directly related to the decrease in overal length.

[taylorguns]

I have to say if you are having nose diving issues get the EGW under sized die. I just purchased a new Limited Elite in 40 S&W for limited class at a local club. I got one factory chrome mag that I installed hennings H-141 mag extension with grams follower and spring. I then used a lee bulge buster to remove the bulge from once fired brass I get from the range. It did not matter what length I loaded them too, I got nose dives every time. After reading a post about how to fix the problem I went out and ordered the parts that I needed. I first checked mag lips and found out that it was out of spec. Then I turned to my case problems. After drilling out the threads and using the under sized die just like the lee bulge buster, problem fixed. No more nose dives and now I get 20 rounds per mag. Once I start using the mags a little more I hope to be able to load 21 per, only time will tell. My current setup is

180gr TC lead

4.2gr WST

any small pistol primer

OAL 1.85

I am not worrying about PF yet until I feel I have the correct setup first.